JPH0727377Y2 - Turbine room of ceramics radial turbine impeller - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention is suitably used for the turbine casing of a turbocharger equipped with a ceramic radial turbine wheel.

"Prior Art" Fig. 2 is a cross-sectional view showing an impeller chamber of a conventional turbocharger equipped with a metallic radial turbine impeller.
Reference numeral 21 is a metallic radial turbine impeller, 21a is a hub portion of the turbine impeller 21, 21b is a blade portion of the turbine impeller 21, 22 is a turbine nozzle, and as is well known, exhaust is a turbine nozzle.
It enters from 22 and is discharged to the outside in the direction of the arrow while rotating the turbine impeller 21. Thus, the rotational force of the turbine impeller 21 is transmitted to a compressor impeller (not shown) provided coaxially to rotate the compressor impeller, thereby functioning as a supercharger.

On the other hand, in order to improve the delay of the acceleration response, which is the biggest problem in the turbocharger, a turbine impeller made of ceramics having a smaller specific gravity than metal has been put into practical use.

"Problems to be solved by the device" However, since ceramics have a lower fracture toughness value than metals, the structure of the turbine casing when a metal turbine impeller is installed is applied when a ceramic turbine impeller is installed. Then, there is a problem that blade cracking, impeller damage, and the like are likely to occur due to the oxide scale jumping in from the exhaust manifold.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to reduce chipping and damage of a ceramic turbine wheel.

"Means for solving the problem" The means is a ceramic radial with a clearance of 2 mm or more between the exhaust inlet side edge of the blade and the housing turbine impeller insertion section facing the side edge. This is the turbine casing of the turbine impeller.

"Operation" The scale does not get caught between the exhaust inlet side edge portion of the blade portion and the housing turbine impeller insert portion facing the side edge portion.
Therefore, chipping of the blade due to biting of the scale is prevented.
The gap was set to 2 mm or more because it was found that the scale of the scale entering the turbine casing from the turbine nozzle was up to 2 mm.

Example 1 Experimental Example 1 FIG. 1 is a sectional view showing an impeller chamber according to an example of the present invention. In FIG. 1, the clearance between the exhaust inlet side edge portion 11c of the blade portion 11b of the turbine impeller 11 and the housing turbine impeller insertion portion 13 facing the side edge portion is 2.5 mm, and the turbine impeller 11 2 is made of a silicon nitride sintered body, and there is no structural difference from the conventional impeller chamber shown in FIG. Turbine impeller 11 for the above impeller room is 80,000 rpm
The iron blades of 2 mmφ and 30 mg were charged from the position 50 mm upstream of the turbine nozzle 12 at a speed of, and the state of the blade 11b was observed. For comparison, an impeller chamber having the same structure as that of the above example except that the gap was 1 mm was assembled, and iron balls were similarly charged to observe the condition of the blade.

Table 1 shows the above observation results.

Experimental Example 2 A turbocharger equipped with a turbine wheel 11 made of a silicon nitride sintered body having a clearance 1 with the housing turbine wheel insert portion 13 being the value shown in Table 2 was attached to a gasoline engine with a displacement of 1800 cc. Rotate 11 at 12 rpm, temperature 950 ℃
While flowing the exhaust gas, the cubic foreign matter made of cast iron was introduced from the exhaust manifold. The weight of foreign matter is 10
For the first time from mg, it increased by 5 mg. And turbine impeller 1
The weight when the maximum length of 1 mm or more was chipped was defined as the weight of the foreign matter.

Table 2 shows the results of measuring the clearance 1, the weight of the foreign matter and the maximum turbine efficiency in the above-mentioned loading test.

As shown in Table 2, when the gap 1 was 1 mm, the limit foreign matter weight was only 15 mg, but when the gap 1 was 2 mm or more, there was no chipping even if the foreign matter weight reached 30 mg,
Moreover, the maximum turbine efficiency was the same as when the gap 1 was 1 mm.

[Advantage of the Invention] As described above, according to the present invention, it is possible to prevent blade breakage of a ceramic turbine wheel without deteriorating the performance of the turbocharger.

[Brief description of drawings]

FIG. 1 is a sectional view showing an impeller chamber according to an embodiment of the present invention. FIG. 2 is a sectional view showing a conventional impeller chamber. 11, 21 ...... Turbine impeller 11b, 21b ...... Blade 11c …… Exhaust inlet side edge 12, 22 …… Turbine nozzle 13 …… Housing Turbine impeller insertion part

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A ceramic radial turbine impeller, characterized in that a gap of 2 mm or more is provided between an exhaust inlet side edge portion of the blade portion and a housing turbine impeller insertion portion facing the side edge portion. Turbine room.