JPH0519598U - Complexes Loud - Google Patents

Abstract

(57) [Summary] [Purpose] Maintaining the clearance accuracy for the impeller of the compressor shroud. [Structure] Thermal spray coating layer 4 cut by impeller 1
In the compressor shroud 2 including the above, the porosity of the sprayed coating layer 4 is gradually reduced from the upstream side to the downstream side.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to the structure of a compressor shroud that constitutes a non-displacement machine such as a tabo charger.

[0002]

[Prior Art]

 In order to improve the compressor efficiency of the turbocharger and the like, there is a demand to minimize the clearance provided between the blade tip of the impeller rotating at high speed and the inner wall surface of the compressor shroud facing the blade tip.

As a countermeasure against this, as shown in FIG. 4, for example, an abradable coating layer 13 that is easy to cut is formed on the inner wall surface of the compressor shroud 2, and the impeller 1 is attached to the compressor shroud 2 in a state of being assembled. There is one in which the coating layer 13 is cut by the blade tip 4 of the above. As a result, the gap provided between the blade tip portion of the impeller 1 and the coating layer 13 is made substantially zero (for example, Japanese Utility Model Laid-Open No. 58-4440 and Japanese Patent Publication No. 52-42906). Gazette, see).

[0004]

[Problems to be solved by the device]

 However, in such a conventional device, the cutting powder generated in the portion of the coating layer 13 facing the upstream side of the impeller 1 is carried to the downstream side, and this cutting powder acts as an abrasive. The gap in the portion of the sprayed coating layer 3 facing the downstream side of the impeller 1 is unnecessarily large, which causes a decrease in compressor efficiency.

Since the coating layer 13 is formed uniformly from the portion facing the upstream side of the impeller 1 to the portion facing the downstream side, when the wear resistance of the coating layer 13 is increased, the cutting of the coating layer 13 is increased. At times, the stress acting on the impeller 1 increased, causing damage or deformation of the impeller 1.

The present invention focuses on the above points and aims to maintain the clearance accuracy of the compressor shroud with respect to the impeller.

[0007]

[Means for Solving the Problems]

 The present invention is directed to a compressor shroud having a sprayed coating layer cut by the impeller blade tips, in which the porosity of the sprayed coating layer is gradually reduced from the portion facing the upstream side of the impeller to the portion facing the downstream side. To do.

[0008]

[Action]

 The thermal spray coating layer is cut by the impeller blade tip with the impeller mounted on the compressor shroud. During this cutting, the cutting powder generated in the portion of the thermal spray coating layer facing the upstream side of the impeller is carried to the downstream side, but the portion of the thermal spray coating layer facing the downstream side of the impeller has a low porosity and wear resistance. Because of its improved performance, this cutting powder prevents the gap between the impeller from becoming larger than necessary. As a result, the gap between the sprayed coating layer and the impeller can be substantially zero from the upstream side to the downstream side, and the compressor efficiency can be improved.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, an impeller 1 and a compressor shroud 2 constitute a compressor of a turbocharger. The impeller 1 rotates at high speed and sucks from an inlet 6 of a compressor shroud 2 as shown by an arrow in the figure. The intake air is accelerated in the radial direction.

A thermal spray coating layer 3 is formed on the inner wall surface of the compressor shroud 2. The thermal spray coating layer 3 is formed on the inner wall surface of the compressor shroud 2 to a predetermined thickness by mixing a resin having a hardness lower than that of the impeller 1 with resin or graphite. The thermal spray coating layer 3 thus formed is porous, and wear resistance is enhanced as the porosity, which is the distribution density of pores, decreases. This porosity changes depending on the particle size of the spray powder, the supply amount of the spray powder, the spray current value, the spray distance, and the like.

As shown in FIG. 2, the distribution density of the pores 5 is large and the porosity is large in the portion A facing the upstream side of the impeller 1 of the thermal spray coating layer 3. On the other hand, in the portion B of the thermal spray coating layer 3 facing the downstream side of the impeller 1, as shown in FIG. 3, the distribution density of the pores 5 is relatively small and the porosity is small.

The thermal spray coating layer 3 is formed by reducing the particle size of the thermal spray powder from the upstream side to the downstream side, reducing the supply amount of the thermal spray powder, increasing the thermal spray current value, or shortening the thermal spray distance. To be done. As a result, the thermal sprayed coating layer 3 is the distribution density of the pores 5, but the porosity changes gradually or continuously so that the porosity gradually decreases from the portion facing the upstream side of the impeller 1 to the portion facing the downstream side. Formed.

Next, the operation will be described.

The sprayed coating layer 3 is cut at the blade tip 4 of the impeller 1 by rotating the impeller 1 after assembling the impeller 1 to the compressor shroud 2. As a result, the portion of the impeller 1 that comes into contact with the blade tip 4 is ground, and the impeller 1 can be prevented from being deformed or damaged even if eccentricity, vibration, or the like occurs in the rotating shaft of the impeller 1.

When the thermal spray coating layer 3 is cut by the blade tip portion 4 of the impeller 1, cutting powder generated by cutting at a portion A of the thermal spray coating layer 3 facing the upstream side of the impeller 1 is downstream of the impeller 1. Although it is carried to the portion B facing the side, since the downstream portion B has a low porosity and high wear resistance, this cutting powder prevents the gap from being excessively large with respect to the impeller 1. As a result, the gap between the sprayed coating layer 3 and the impeller 1 can be substantially zero from the upstream side to the downstream side, and the compressor efficiency can be improved.

On the other hand, when the thermal spray coating layer 3 is formed with its porosity uniformly reduced, it is possible to avoid an increase in the gap with respect to the impeller 1 due to the cutting powder generated on the upstream side. It is difficult to sufficiently secure the strength of the blade tip 4 and the possibility that the blade tip 4 comes into contact with the thermal spray coating layer 3 and breaks increases.

[0018]

[Effect of the device]

 As described above, according to the present invention, in the compressor shroud including the sprayed coating layer cut by the blade tip of the impeller, the porosity of the sprayed coating layer is gradually reduced from the upstream side to the downstream side, and therefore the downstream side of the sprayed coating layer is formed. On the side, it is possible to prevent the clearance against the impeller from unnecessarily increasing due to cutting powder and maintain high compressor efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of the thermal spray coating layer in the portion A of FIG.

FIG. 3 is a sectional view of the thermal spray coating layer in the portion B of FIG.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Impeller 2 Compressor shroud 3 Thermal spray coating layer 4 Blade tip 5 Pore

Claims (1)

[Scope of utility model registration request] 1. In a compressor shroud including a sprayed coating layer cut by a blade end of an impeller, the porosity of the sprayed coating layer is gradually reduced from a portion facing the upstream side of the impeller to a portion facing the downstream side. A compressor shroud characterized by being formed.