JPH0440559B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION This invention relates to a compressor housing for an automobile turbocharger. BACKGROUND ART As shown in FIG. 6, an automobile turbocharger introduces exhaust gas from an exhaust manifold of an engine to a turbine housing 1 to rotate a turbine wheel 2, and then directs the exhaust gas from an exhaust manifold of an engine to a turbine housing 1 to rotate a turbine wheel 2. The rotation of the connected impeller 4 compresses intake air within the compressor housing 5, and the compressed intake air is sent to the engine. The compressor housing 5 in such an automobile turbocharger is generally made of aluminum alloy casting, and the impeller 4 is generally made of a heat-resistant aluminum alloy casting that has been quenched and tempered. By the way, in an automobile turbocharger, reducing the gap H between the tip of the impeller 4 and the inner wall surface of the compressor housing 5 facing it as small as possible improves the turbo efficiency (compressor efficiency). Known to be beneficial. However, if this gap H is made too small, the tip of the impeller 4 may come into contact with the compressor housing 5 due to slight eccentricity or vibration of the shaft 3 during rotation, and the impeller 4 may be damaged. Therefore, the gap H between the compressor housing 5 and the impeller 4 of conventional automotive turbochargers is required to be at least 0.3 to 0.5 mm, although it varies depending on the size of the turbocharger. Ta. Problems to be Solved by the Invention As mentioned above, in conventional automotive turbochargers, the minimum gap H between the inner wall surface of the compressor housing and the impeller is 0.3 to 0.5 mm.
is necessary, and this gap has been a major cause of not being able to further improve turbo efficiency. On the other hand, although it is different from an automotive turbocharger, in order to minimize power loss in a turbine engine, it is preferable to minimize the gap between the turbine casing and the turbine blades. I had a similar problem with Jiya. Therefore, for gas turbine engines, a proposal has been made to prevent damage to the turbine blades by constructing the turbine casing from ceramic, which is softer than the turbine blades, as shown in Japanese Patent Publication No. 50-690. However, applying this proposal to automotive turbochargers and constructing the entire compressor housing from a material softer than the rotating member (in this case, the impeller) would result in a significant increase in material costs.
It's not realistic. Regarding gas turbine engines for aircraft, Japanese Patent Application Laid-open No. 52-72335 or No. 85031 No. 52-85031
As shown in the issue, a mixed powder of alloy powder such as Ni-Cr alloy powder or Al-Cu alloy and Ni graphite powder coated with Ni is thermally sprayed onto the surface of the compressor casing. A technique has been proposed in which the coating is cut by a rotating blade as a mating material to adjust the gap between the casing and the rotating blade. However, this technique is intended for aircraft gas turbine engines, and is not intended to be applied to automobile turbochargers. Furthermore, when attempting to apply this technology for aircraft gas turbine engines to automobile turbochargers, the following disadvantages occurred. That is, when spraying the thermal spray material used in the above proposal onto the compressor housing of an automobile turbocharger, and attempting to adjust the gap by cutting the thermal spray coating as it is by rotating the impeller, Base metal for thermal spray coating
The hardness of Ni-Cr alloy and Al-Cu alloy is usually higher than that of the impeller (usually cast Al-Si alloy), and the interlayer strength of the thermal spray coating is high, so the impeller in contact with the coating does not rotate. Or, even if the impeller rotates, there is a problem that the impeller wears heavily during cutting. In addition, when using the above-mentioned thermal spray materials, in order to prevent the coating from peeling off due to shear stress at the interface between the base material (compressor housing) and the thermal spray coating, which occurs when the thermal spray coating is cut with an impeller after thermal spraying. , it is necessary to spray a base material such as a Ni-based alloy material on the surface of the base material in advance in the adhesion direction, but forming such a base spray layer is useful for applications in automotive turbochargers. Problems arise in terms of productivity. This invention was made against the background of the above circumstances, and is used as a compressor for an automobile turbocharger by reducing the gap between the impeller and the compressor housing without causing the above-mentioned inconveniences, and improving turbo efficiency by reducing the gap between the impeller and the compressor housing. The object of the present invention is to provide a compressor housing that can be significantly improved. Means for Solving the Problems This invention basically consists of a mixture of soft metal and resin or graphite on the wall surface of the portion facing the tip of the impeller in the compressor housing of an automobile turbocharger. It is characterized by a thermally sprayed coating consisting of a composite structure that has a shape. Here, it is desirable that the thermal spray coating is configured such that the ratio of resin or graphite in the coating decreases from the coating toward the housing base material. Further, as the soft metal in the thermal spray coating, it is desirable to use a metal that is softer than the material of the impeller. Effect Thermal sprayed coatings that contain a mixture of soft metal and resin or graphite are not only soft, but also have a composite structure with weak bonding strength between laminated particles due to the combination of materials with poor wettability. As a result, machinability is extremely excellent. Therefore, the inner wall surface of the air passage part of the compressor housing, especially the part facing the tip of the impeller, is coated with a sprayed coating with a thickness that is approximately equal to or slightly larger than the gap between the compressor housing and the impeller. If the impeller is installed in the formed state and the impeller is rotated, the tip of the impeller contacts the thermal sprayed coating as it rotates, and the surface of the thermal sprayed coating is easily scraped off by the thickness of the contact. Adjustment is made so that the gap is substantially zero. In other words, while the gap between the compressor housing and the impeller was at least 0.3 to 0.5 mm as mentioned earlier, it was decided to form a thermally sprayed coating as described above and cut it with the impeller. Therefore, the gap is reduced to substantially zero, and therefore turbo efficiency (compressor efficiency) can be significantly improved. Here, the cutting of the thermal spray coating by the impeller is as follows:
It is most desirable to assemble the compressor housing and the actual impeller into the actual turbocharger and run it under running conditions, but in some cases it is possible to use a pseudo impeller made to the same dimensions as the actual impeller. You may do so. Since the thermal spray coating is a composite coating made of soft metal and resin or graphite, it may have poor adhesion strength to the base material of the compressor housing if left as is. composing the server housing
Alternatively, a method may be adopted in which a base sprayed layer such as a Ni-based alloy is formed in advance on the surface of an Al casting or the like. However, as mentioned above, if the ratio of resin or graphite in the thermal sprayed coating in which soft metal and resin or graphite are mixed decreases from the coating surface toward the compressor housing base material, The adhesion of the sprayed coating can be improved without forming a sprayed layer. In other words, reducing the proportion of resin or graphite in the sprayed coating from the coating surface toward the compressor housing base material means, conversely, that the proportion of soft metal decreases from the coating surface toward the compressor housing base material. means increasing. If the ratio of soft metal is 100% or close to 100% near the compressor housing base material, the relationship between the compressor housing base material and the sprayed coating may be reduced even if the base sprayed layer is not formed. Since the metals are almost in contact with each other at the interface, sufficient adhesion of the sprayed coating is ensured. In addition, as mentioned above, when reducing the ratio of resin or graphite in a thermal sprayed coating containing a mixture of soft alloy and resin or graphite from the coating surface toward the compressor base material, it is necessary to Or the ratio of graphite
If it is configured to be 100% or close to 100%, the hardness near the surface of the thermal sprayed coating becomes substantially the hardness of the resin or graphite itself, making cutting extremely easy. In other words, when the impeller is installed and the thermal sprayed coating is cut, only the surface layer of the thermal sprayed coating is actually cut, and therefore, as mentioned above, the area near the surface of the thermal sprayed coating is essentially only resin or graphite. If it becomes,
Cutting by rotating the impeller becomes extremely easy, and it is possible to effectively prevent situations where the impeller does not rotate even if the impeller is installed and the impeller tries to rotate, or situations where the tip of the impeller is severely worn out. . Among the constituent materials of the thermal spray coating, the soft metal only needs to have the same hardness as the material of the impeller or be softer. For example, if the impeller is a heat-resistant aluminum alloy casting (Al-Si alloy) and the compressor is If the housing is cast aluminum,
As the soft alloy for the thermal spray coating, Al, Al--Si alloy, Ni, etc. can be used. Furthermore, in order to particularly improve the machinability of the thermal spray coating and prevent wear and deformation of the impeller, the above-mentioned soft metal should be a metal that is much softer than the impeller material (Al-Si alloy), such as Zn, It is desirable to use Pb, Sn, or an alloy thereof. In addition, the resin used for the thermal spray coating must be a thermoplastic resin that can be thermally sprayed at the same time as a soft metal.
Any material that is softer than the soft alloy may be used, and for example, polyester, poly(paraoxybenzoyl) ester, poly(paraoxybenzoylmethyl) ester, nylon, etc. can be used. Furthermore, the proportion of soft metal in the sprayed coating is
It is preferably within the range of 5 to 95% by weight. In addition, as the thermal spray powder, a mixed powder obtained by mechanically mixing the above-mentioned soft metal powder and resin or graphite powder, or a composite powder in which graphite or resin particles are coated with a soft metal may be used. It's okay. On the other hand, the thickness of the sprayed coating is approximately equal to or slightly larger than the gap between the compressor housing and the impeller tip, specifically about -0.1 to ±0.2 mm relative to the gap between the compressor housing and the impeller tip. It is preferable to set it within the range of. Embodiment As shown in FIG. 1, in the air flow section of the compressor housing 5 made of aluminum casting, a soft alloy, resin, or graphite is used especially in the portion facing the tip of the impeller 4 (see FIG. 6). An example will be shown below in which a thermal sprayed coating 6 containing a mixture of impellers was formed, and the thermal sprayed coating 6 was further cut using an actual impeller or a pseudo impeller. In addition, among the following examples, Examples 1 to 3 are those in which the ratio of resin or graphite in the thermal sprayed coating was not particularly changed in the thickness direction, and a base thermal sprayed layer was formed.
Further, in Examples 4 to 6, graded thermal spraying was performed so that the ratio of resin or graphite in the thermal sprayed coating was changed without forming a base thermal spraying layer. Example 1 The compressor housing used in Example 1 had a gap H with the impeller of 0.5 mm and an impeller diameter of 65 mm. First, shot blasting was applied to the part of the compressor housing facing the impeller tip. The blasting material used has a particle size of calcined alumina.
It is 1200 to 1400 μm. Next, apply 80wt%Ni-20wt to that area to improve adhesion.
%Cr alloy base sprayed layer 7 (see Figure 2)
was formed with a thickness of 0.08 to 0.1 mm by plasma spraying. Furthermore, on the base thermal sprayed layer 7, a thermal sprayed coating 6 for gap adjustment, which is a feature of the present invention, is formed.
A 60wt% (Al-12wt%Si)-40wt% polyester mixed powder was sprayed by plasma spraying. The film thickness t at this time is 0.5 including the base sprayed layer 7.
It was controlled to be ~0.6mm. The structure of the sprayed coating 6 thus sprayed is shown in FIG. In Figure 3, the white parts are aluminum alloy and the black parts are polyester. After the compressor housing 5 with the thermal spray coating 6 formed thereon as described above is assembled into an actual turbocharger together with the impeller 4, the thermal spray coating is removed by rotating the impeller 4 as shown in FIG. 6 was cut. At this time, the rotation speed of the impeller 4 was set to 5000 rpm, and the impeller 4 was rotated for 30 minutes until no shavings 61 of the sprayed coating 6 came out. As a result, the total thickness of the base thermal spray layer 7 and the thermal spray coating 6 is the same as that of the original impeller 4 and compressor housing 5.
This resulted in a compressor housing having a clearance H substantially equal to that of the compressor housing. Example 2 The compressor housing used in Example 2 had a gap H with the impeller of 0.5 mm and an impeller diameter of 110 mm. First, the part of the compressor housing facing the impeller tip was shot blasted using steel grid as the blasting material. Next, in order to improve adhesion, a base sprayed layer 7 consisting of 94wt% (80wt%Ni-20wt%Cr)-6wt%Al was applied to the area using a plasma spraying method of 0.08%.
It was formed with a thickness of ~0.1 mm. Furthermore, on top of the base thermal sprayed layer 7, a thermal sprayed coating 6 of 70wt% (Al-5wt%Si)-
A 30wt% graphite mixed powder was sprayed by plasma spraying. The film thickness at this time was adjusted to 0.6 mm including the base thermal sprayed layer 7. After the compressor housing 5 on which the thermal spray coating 6 was formed in this way is assembled together with the impeller 4 into an actual turbocharger, the impeller 4
The thermal spray coating 6 was cut by rotating the .
At this time, the rotation speed of impeller 4 is 7000 rpm,
Rotation was continued for 40 minutes until the scraped layer of the sprayed coating 6 no longer appeared. Example 3 The compressor housing used in Example 3 has a gap H between it and the impeller of 0.3 to 0.4 mm and an impeller diameter of 50 mm. First, blast material with a particle size of 1200 was applied to the part of the compressor housing facing the impeller tip.
Shot blasting was performed using ~1400 μm calcined alumina. Next, in order to improve adhesion, a base sprayed layer 7 made of 80wt%Ni-20wt%Cr alloy is applied to the area by gas spraying with a thickness of 0.05 to 0.07%.
It was formed with a thickness of mm. Furthermore, a 70wt% Ni-30wt% graphite mixed powder was sprayed onto the base sprayed layer 7 by a gas spraying method as a sprayed coating 6 for gap adjustment, which is a feature of the present invention. The thickness of the coating at this time was adjusted to 0.4 mm including the base sprayed layer 7. After the pseudo impeller was assembled into the compressor housing 5 on which the sprayed coating 6 was formed in this way, the sprayed coating 6 was cut by rotating the pseudo impeller. At this time, the number of rotations of the pseudo impeller was set to 10,000 rpm, and the rotation was continued for 10 minutes until no shavings of the thermally sprayed coating 6 were produced. The turbochargers using the compressor housings according to Examples 1 to 3 above were operated at a rotational speed of 100,000 rpm to examine compressor efficiency. For comparison, the compressor efficiency of the same turbocharger was also investigated before thermal spraying. The results are shown in Table 1.

[Table] As shown in Table 1, it was confirmed that when a compressor housing on which a thermal spray coating according to the present invention was formed was used, compressor efficiency was improved by 3 to 4% compared to before thermal spraying. This is because the gap between the compressor housing and the impeller can be made as close to zero as possible by forming a thermal spray coating, and as a result, power loss can be minimized. Example 4 The compressor housing used in Example 4 had a gap H with the impeller of 0.5 mm and an impeller diameter of 65 mm. First, the part of the compressor housing facing the tip of the ipeller was subjected to sheet blasting treatment, and as shown in Figures 4 and 5, aluminum-silicon alloy (Al-12wt%Si) and polyester were applied to that part.
Graded thermal spraying was performed using the plasma spraying method so that the ratio of these changes in the thickness direction.
A sprayed coating 6 with a thickness of ~0.6 mm was formed. That is, as shown in detail in FIG. 5, the vicinity of the side in contact with the compressor housing 5 is substantially made of aluminum.
A thermal sprayed coating 6 is formed in which only silicon alloy 6A is present, and the ratio of polyester 6B gradually increases toward the top of the coating, so that the surface layer cut by impeller 4 is substantially only polyester 6B. did. After the compressor housing 5 on which the thermal spray coating 6 was formed in this way was assembled together with the impeller 4 into an actual turbocharger, the
The thermal spray coating 6 was cut by rotating the impeller 4 as shown in the figure. At this time, the impeller rotation speed was 10,000 rpm, and the impeller was rotated for 30 minutes until no shavings of the sprayed coating came out, and the gap was reduced to substantially zero. Example 5 The compressor housing used in Example 5 had a gap H with the impeller of 0.3 to 0.4 mm and an impeller diameter of 50 mm. First, shot blasting is applied to the part of the compressor housing facing the impeller tip, and graded spraying of pure nickel and graphite is applied to that part using plasma spraying so that the ratio of these changes in the thickness direction. te 0.4～
A thermal spray coating 6 with a thickness of 0.5 mm was formed. In other words, the area near the side in contact with the compressor housing 5 is essentially made of only nickel, and the ratio of graphite gradually increases toward the top of the coating, so that the surface layer cut by the impeller 4 is substantially made of nickel. A thermal sprayed coating 6 consisting only of graphite was formed. After the compressor housing 5 on which the thermal spray coating 6 was formed in this way is assembled into an actual turbocharger together with the impeller 4, the impeller 4
The thermal spray coating 6 was cut by rotating the .
At this time, the impeller rotation speed was 10,000 rpm, and the impeller was rotated for 30 minutes until no shavings of the sprayed coating came out, and the gap was reduced to substantially zero. Example 6 The compressor housing used in Example 6 had a gap H with the impeller of 0.3 to 0.4 mm and an impeller diameter of 50 mm. First, shot blasting is applied to the part of the compressor housing facing the impeller tip, and then an aluminum-silicon alloy (Al-Silicon alloy) is applied to that part.
A sprayed coating 6 having a thickness of 0.4 to 0.5 mm was formed by graded thermal spraying of 12 wt% Si) and graphite using a plasma spraying method so that the ratio thereof varied in the thickness direction. In other words, the area near the side in contact with the compressor housing 5 is essentially made only of aluminum-silicon alloy, and the ratio of graphite gradually increases toward the top of the coating, and the surface layer cut by the impeller 4. A thermally sprayed coating 6 was formed in which the material consisted essentially of graphite. After the compressor housing 5 on which the thermal spray coating 6 was formed in this way is assembled into an actual turbocharger together with the impeller 4, the impeller 4
The thermal spray coating 6 was cut by rotating the .
At this time, the impeller rotation speed was 10,000 rpm, and the impeller was rotated for 30 minutes until no shavings of the sprayed coating came out, and the gap was reduced to substantially zero. The turbochargers using the compressor housings according to Examples 4 to 6 above were operated at a rotation speed of 100,000 rpm for 50 minutes, and the condition of the coating and the condition of the impeller were investigated. For comparison, we also conducted an actual operating test on a compressor housing that had been sprayed with simple mixture spraying instead of graded spraying, that is, spraying that did not change the ratio of soft metal and resin or graphite in the thickness direction. conducted an investigation. The thermal spray powders used for comparison were as shown in the following Comparative Examples A to C, Examples 4 to 6.
It corresponded to Comparative Example A: For comparison with Example 4, 60 wt% (Al
-12wt%Si)-40wt% polyester mixed powder Comparative example B: For comparison with Example 5, 75wt%Ni-
Comparative Example C using 25wt% graphite mixed powder: For comparison with Example 6, 65wt% (Al
-12wt%Si) -35wt% graphite mixed powder was used.In the thermal spraying of these Comparative Examples A to C, no base thermal spraying was performed in advance. Further, this is similar to Examples 4 to 6 in that after thermal spraying, the thermal sprayed coating was cut by rotating the impeller to make the gap substantially zero. Table 2 shows the survey results after the actual machine operation test.

[Table] The one that rotates smoothly is better, the one that rotates more easily.
What has happened is considered evil.
In Examples 4, 5, and 6, the thermal sprayed coating was substantially 100% metal at the interface with the compressor housing, so the thermal sprayed coating remained intact even though no base sprayed layer was formed. Adhesion was good, and no damage to the sprayed coating such as peeling occurred. On the other hand, in Comparative Examples A and B, since no base sprayed layer was provided, adhesion was insufficient and the sprayed coatings peeled off. In addition, in Examples 4, 5, and 6, the impeller of the thermal sprayed coating has good machinability and the amount of impeller wear is small, but this is because the portion near the surface of the thermal sprayed layer is
This is because it is nearly 100% polyester or graphite. Further, Examples 7 and 8 in which a metal much softer than the impeller material was used as the soft metal in the thermal spray coating are shown below. Example 7 The compressor housing used in Example 7 had a gap H with the impeller of 0.5 mm. First, shot blasting is applied to the part of the compressor housing facing the impeller tip, and a Ni-Cr alloy is applied to that part as a base thermal spray layer.
After thermal spraying to a thickness of 0.1mm, a layer of 0.4~
A thermal spray coating 6 was formed with a thickness of 0.5 mm. The mixed powder of Pb and graphite has a particle size of 15 to 44 μm.
Pb particles and graphite powder with a particle size of 44 to 90 μm
It is mechanically mixed so that Pb is 70wt% and graphite is 30wt%. After the compressor housing 5 with the sprayed coating 6 formed thereon was assembled into an actual cutting turbocharger together with the impeller 4 made of an Al-Si alloy, the sprayed coating 6 was cut by rotating the impeller 4. . The impeller rotation speed at this time was 10,000 rpm, and the impeller was rotated for 30 minutes until no shavings of the sprayed coating were produced, and the gap H was reduced to substantially zero. Example 8 The compressor housing used in Example 8 had a gap H with the impeller of 0.4 mm. First, shot blasting is applied to the part of the compressor housing facing the impeller tip, and a Ni-Cr alloy is applied to that part as a base thermal spray layer.
After thermal spraying to a thickness of 0.1 mm, a thermal spray coating 6 was formed to a thickness of 0.3 to 0.4 mm by a gas spraying method using Sn-plated graphite powder (particle size 30 to 90 μm). After the compressor housing 5 with the sprayed coating 6 formed thereon was assembled into an actual cutting turbocharger together with the impeller 4 made of an Al-Si alloy, the sprayed coating 6 was cut by rotating the impeller 4. . The impeller rotation speed at this time was 10,000 rpm, and the impeller was rotated for 30 minutes until no shavings of the sprayed coating were produced, and the gap H was reduced to substantially zero. The turbochargers using the compressor housings according to Examples 7 and 8 were rotated at a rotational speed of 100,000 rpm for 60 minutes, and the condition of the coating and the condition of the impeller were investigated. For comparison, compressor housings (Comparative Examples D, E, and F) in which the thermal spray coating was formed using a mixed powder of metal and resin or graphite with the same hardness as the impeller material were also shown. The same investigation as above was carried out using the same actual machine operation as above. The thermal spray powders used for comparison here are as shown in Comparative Examples D to F below. Comparative example D: 60wt% (Al-12wt%Si)-40wt% polyester Comparative example E: 75wt%Ni-25wt% graphite Comparative example F: 65wt% (Al-12wt%Si)-35wt% graphite These comparisons Among Examples D to F, Comparative Example D,
Comparative Example E is applied to a compressor housing similar to Example 7, and Comparative Example F is applied to a compressor housing similar to Example 8.
Further, in thermal spraying in Comparative Examples D to F, base thermal spraying was performed in the same manner as in Examples 7 and 8. Also, as in Examples 7 and 8, the thermal sprayed coating was cut by rotating the impeller after thermal spraying, and the gap was made zero. Table 3 shows the investigation results after the actual machine operation test.

[Table] Things that are difficult to change are considered evil.
As shown in Table 3, in Examples 7 and 8 and Comparative Examples D to F, no damage occurred to the sprayed coatings, but the machinability with the impeller was lower in Comparative Examples E and F.
The impeller rotation was not smooth. Moreover, the amount of impeller wear was significantly smaller in Examples 7 and 8 than in Comparative Examples D to F. Furthermore, the impeller was modified in Example 7,
In the case of No. 8, the amount was significantly lower than in the cases of Comparative Examples D to F. These differences are because the hardness of the soft metal in the thermal sprayed coatings of Comparative Examples D to F was comparable to that of the impeller, whereas the hardness of the soft metal in the thermal sprayed coatings of Examples 7 and 8 was higher than that of the impeller. It is thought that this was caused by the fact that it was also soft. Effects of the Invention As is clear from the above embodiments, the automotive turbo compressor housing of the present invention has the following features:
A thermally sprayed coating containing a mixture of soft metal and resin or graphite is formed on the wall surface of the portion facing the tip of the impeller. By cutting the part, the gap between the housing and the impeller can be reduced to virtually zero, and as a result, the compressor efficiency (turbo efficiency) is significantly improved compared to when no thermal spray coating is provided. can be improved. When the impeller cuts the thermal sprayed coating, the thermal sprayed coating is formed by a composite structure consisting of laminated particles with weak bonding strength, so the thermal sprayed coating is easily cut, and the cutting debris is removed by the laminated particles peeling off. Since the resulting particles are fine, it is possible to prevent them from getting entangled with or adhering to the impeller, etc., and it is possible to prevent problems such as the thermal spray coating being further scraped by cutting waste. In particular, according to an embodiment in which the ratio of resin or graphite in the thermal spray coating decreases from the coating surface toward the housing base material, adhesion can be ensured and peeling of the coating can be prevented. This eliminates the need for the process of forming a base layer, which improves productivity, and also prevents the impeller from rotating smoothly or causing impeller wear when removing the surface of the thermally sprayed coating. It is possible to effectively prevent a situation from progressing violently.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the compressor housing of the present invention, and FIG. 2 is a schematic cross-sectional view schematically showing a situation in which the thermal spray coating is cut by an impeller in the compressor housing of Example 1. Figure 3 is a photograph of the metal cross-sectional structure of the thermal sprayed coating of Example 1 (magnification: 100x), and Figure 4 schematically shows the situation in which the thermal sprayed coating is cut by an impeller in the compressor housing of Example 4. 5 is an enlarged sectional view of part A in FIG. 4; FIG. 6 is a vertical sectional view showing an example of an automobile turbocharger to which the compressor housing of the present invention is applied. It is. 4... Impeller, 5... Compressor housing, 6... Thermal spray coating.

Claims (1)

[Claims] 1. A thermal sprayed coating consisting of a composite structure in which soft metal and resin or graphite are mixed is formed on the wall surface of the portion of the compressor housing of an automobile turbocharger that faces the tip of the impeller. An automotive turbo compressor housing characterized by: 2. The turbo compressor housing for an automobile according to claim 1, wherein the ratio of resin or graphite in the radiation coating decreases from the coating surface toward the housing base material. 3. The turbo compressor housing for an automobile according to claim 1, wherein a metal softer than the impeller is used as the soft metal in the thermal spray coating.