JPH01147118A - Impeller for automobile turbocharger - Google Patents

Abstract

PURPOSE:To make sure of spacing adjustment between an impeller and a compressor as well as to make the extent of turbine efficiency improvable by constituting a blade tip part of the impeller contacting with the compressor with a fiber-reinforced metal. CONSTITUTION:An abradable spray deposit is formed in a part being opposed to a tip of an impeller 4 in particular out of air passing parts of a compressor housing consisting of an aluminum alloy casting. In this impeller 4 for a turbocharger, such light alloy materials such as an aluminum alloy and an Mg alloy or the like are used for its base material part in due consideration of light weightiness. The tip part, namely, a blade tip part A contacting with the abradable spray deposit at the time of impeller rotation is constituted of a fiber-reinforced metal (FRM), namely, a fiber-metal composite material made up of reinforcing the metal with a ceramic fiber or the like.

Description

[Detailed description of the invention] Industrial application field This invention is unique! Regarding the impeller (rotary vane) used in the compressor of the IJ municipal tarpochi P-ger, in particular, by assembling the impeller into the compressor housing and rotating it, the abradable thermal sprayed coating on the surface of the compressor housing is cut by the tip of the impeller, This invention relates to an impeller used in an automobile turbocharger that adjusts the gap between the impeller and the compressor housing.

The conventional technology for automotive turbochargers is as shown in Figure 2.
Exhaust gas from the exhaust manifold of the engine is guided to the turbine housing 1 to rotate the turbine wheel 2, and the rotation of the impeller 4 connected to the turbine wheel 2 via the shaft 3 compresses intake air in the compressor housing 5. , which sends the compressed intake air 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 material obtained by hardening and refurbishing a heat-resistant aluminum base metal.

By the way, in the automotive turbocharger V-, it is important to make 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.
It is known to be advantageous in improving turbo efficiency (compressor efficiency). 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. The gap H between the compressor housing 5 and the impeller 4 of a turbocharger varies depending on the size of the turbocharger, but the minimum is 0.3 to 0.51! This gap is a major reason why it is not possible to further improve the turbo efficiency.

By the way, regarding the gas turbine engine for navigation nitrogen reform,
JP-A-52-72335 or JP-A-52-850
31M, etc., an easy-to-cut composite thermal sprayed coating consisting of metal and a soft non-metallic material with lubricating properties such as graphite or resin, that is, a so-called abradable solvent coating, is formed on the surface of the compressor casing. death,
A technique has been proposed in which the sprayed coating is cut by a rotating blade as a mating material to adjust the gap between the casing and the rotating blade.

Therefore, the present inventors are conducting research on the practical application of the technology used in aviation gas turbine engines as described above to automotive turbochargers. In other words, automotive turbocharger 1? - An easy-to-cut abradable solvent film is formed on the surface of the compressor housing, and by assembling the impeller to the compressor housing and actually rotating it, the abradable sprayed film is cut off at the tip of the impeller, and the impeller and compressor housing are separated. We are progressing with the practical application of technology to adjust the gap between. In such automotive turbochargers, the gap between the compressor housing and the impeller can be adjusted to an extremely small value close to zero, so it is expected that the turbo efficiency will be significantly improved compared to conventional ones.

Problems to be Solved by the InventionAluminum alloys are usually used as impellers in automatic turbochargers due to their light weight, etc.Aluminum alloys, on the other hand, are used as abradable thermal sprayed coatings for gap adjustment as mentioned above. is A1 alloy-resin system or Ni
It has been considered to use a composite material, such as an alloy-graphite system, which has a metal and a soft, non-gold material having self-lubricating properties. When such an abradable thermal spray coating is formed on a compressor housing, the impeller tip may be deformed or worn due to sliding between the impeller tip and the thermal spray coating during the initial rotation of the impeller.
As a result, the shape of the tip of the impeller changes greatly from its original shape, creating a locally large gap between it and the compressor housing, which causes air leakage when using a turbocharger. It may not be possible to sufficiently improve efficacy.

In other words, although the overall hardness of the abradable thermal spray coating is lower than that of an impeller made of A1 alloy, the metal components mixed in the abradable coating attack the impeller, causing deformation and wear at the tip of the impeller. It is thought that it may cause

This invention was made against the background of the above-mentioned circumstances, and provides an automotive turbo in which an abradable solvent reflection is formed on the surface of a compressor housing, and the gap is adjusted by cutting the abradable sprayed coating by rotating an impeller. It is an object of the present invention to provide an impeller for a turbocharger for a motor vehicle, which can sufficiently improve turbo efficiency by preventing deformation and wear of the impeller.

Means for Solving the Problems This invention reduces the gap between the impeller and the compressor housing by rotating the impeller assembled to the compressor housing and cutting the abradable thermal sprayed coating on the surface of the compressor housing with the tip of the impeller. An adjustable impeller for an automotive turbocharger P- is characterized in that the base material is made of a light alloy material, and the part that comes into contact with the abradable thermal sprayed coating on the surface of the compressor housing is made of fiber-reinforced metal. It is something.

Function The impeller of the automotive turbocharger of this invention has the following features:
Light alloy materials such as A2 alloy and M9 alloy are used for the base material with emphasis on light weight, but the tip portion, that is, the wing tip that comes into contact with the abradable thermal spray skin when the impeller rotates, is made of fiber reinforced metal (FRM). ), that is, it is composed of a fiber-metal composite material in which metal is reinforced with ceramic fibers or the like. Such FRM has much higher strength and hardness than light alloy materials such as A2 alloy as a base material, and therefore has excellent early wear resistance and deformation resistance. Therefore, when cutting the abradable thermal sprayed coating on the surface of the compressor housing with the tip of the impeller by inserting the impeller into the compressor housing and rotating the impeller to adjust the gap between the impeller and the compressor housing, the impeller comes into contact with the abradable thermal sprayed coating. It is possible to effectively prevent the tip from being worn out or deformed. Therefore, the gap between the impeller and the compressor housing can be adjusted to a uniform value close to zero, which effectively prevents sudden air leakage between the impeller and the compressor housing when using a turbocharger. By preventing this, compressor efficiency (turbo efficiency) can be sufficiently increased. Further, since the wear of the impeller tip is reduced not only during gap adjustment but also during normal use, there is less risk that turbo efficiency will decrease due to gap enlargement during use.

Specific Description for Carrying Out the Invention In the impeller of the automobile turbocharger of the present invention, light alloy materials such as A1 alloy and MQ gold alloy are used as the base metal. Also, the tip of the impeller (the tip of the blade)
The FRM used in FRM is a composite material in which reinforcing fibers such as ceramic fibers are integrally fixed to a light alloy material of Ae-gold alloy as a base material. Here, as reinforcement II, for example, A
i'203.5i02, ZrO2, SiC.

, SiN, TiN, TiC1, Sialon, etc., or a mixture thereof, and the fibers are usually in the form of long fibers or whiskers, but in some cases, long fibers may also be used. Available for use. The fibers are preferably oriented two-dimensionally randomly on a plane parallel to the blade surface of the impeller, or radially from the axis of the impeller toward the tip. Furthermore, although there are no specific measures for fixing the reinforcing fibers to the composite, since the impeller is generally cast, the reinforcing 41i fibers are set at the required locations within the mold, and the impeller It is unacceptable to combine them into one at the time of construction.

On the other hand, the abradable thermal sprayed coating on the inner surface of the compressor housing, which is a mating material for the impeller, only needs to be easily cut by the impeller, and its material is not particularly limited, but it is usually A2, PB, Sn, Zn, or any of these materials. Soft metals such as alloys and I! such as polyester and polystyrene. A composite material made of A fat or graphite and a soft non-metallic material having lubricity is used.

Embodiment An embodiment in which the present invention is applied to an automobile turbocharger as shown in FIG. 2 will be described below.

[Example 1] First, as shown in Figure 2! An abradable thermal sprayed coating was formed in the following manner on the air passage portion of the compressor housing 5 made of a chimney alloy, particularly on the portion facing the tip of the impeller 4.

That is, after degreasing and shot blasting the surface of the compressor housing base material facing the impeller, a plasma spraying device was used to spray the A500
The base material was preheated to 100 to 150'C under the conditions of A, Ar flow 190 Z/min and H2 flow hanging 2 S/min, and then Ni-4,5wt% A2 alloy was applied to the area facing the impeller as described above. Plasma spraying was performed under the same conditions to form a base sprayed layer with a thickness of 0.1 mm, and then <Al-121%3 i )- for gap adjustment was applied on the base sprayed layer under the same conditions as above.
4 (hvt% Polyvarnish T) was thermally sprayed to a thickness of 0.5rRIn to form an abradable thermal sprayed coating, and the compressor housing was completed. Approximately 0.5m@uno.

On the other hand, as shown in FIG.
The one grown in was created as follows. That is, A12, which is an Al2O3 short fiber, is used as the reinforcing fiber.
Using 03-5% SiO2 (average fiber diameter 2 to 3 mm, average fiber length 2 to 3 mm), the fiber molded body was preheated to 400°C and set in a high-pressure poetry mold for impeller casting. , JIS AC4 as A2 alloy for impeller in mold
0 alloy at a pouring temperature of 400°C and a pressing force of 100°C.
0Kg/c waste is added to create a high-pressure atmosphere, and the shoulder part 4A is FR.
An impeller 4 was obtained in which the base material was made of M and the base material was made of A2 alloy.

[Example 2] As reinforcing fibers used in the FRM of the shoulder portion 4A of the impeller 4, short fibers of A & 203-52% SiO2 (average fiber diameter 2 to 3 mm, average PA fiber length 2 to 3 mm) were used. The impeller 4 was created in the same manner as in Example 1 except that the compressor housing 5 was the same as in Example 1.

[Example 31 SiC whiskers (average diameter 0.1 to 0.34
An impeller 4 was produced in the same manner as in Example 1, except that fi, the average length was 100 lines.

The compressor housing 5 is exactly the same as in the first embodiment.

[Evaluation area p! A] The impellers and compressor housings according to Examples 1 to 3 described above were each inserted into actual turbochargers and operated at a rotational speed of 10,000 rpm for 180 minutes, and the wear amount of the impeller and the turbo efficiency were measured. For comparison, a similar investigation was conducted using a conventional impeller that does not use FRM (that is, an impeller that is entirely composed of AC4DC10). The results are shown in Table 1. In Table 1, "degree of turbo efficiency improvement" means:
The graph shows the turbo effect ratio when compared to the case where a compressor housing without an abradable thermal spray coating is used.

Table 1 As shown in Table 1, the wear amount of the impeller is 1/! in Examples 1 to 3 of this invention! Around t/-, conventional A
T? When using an impeller made only of alloy (comparative example)
Compared to the above, there were fewer wing tips, and no deformation of the wing tips was observed. This is thought to be because the shoulder portion of the impeller is strengthened by FRM. Since there is less wear on the impeller bristles, there is less air leakage between the impeller and the compressor housing during operation, and there is less significant decrease in turbo efficiency.

On the other hand, when using an impeller made only of A2 alloy in the comparative example, the degree of improvement in turbo efficiency was slightly smaller due to gradual wear and deformation of the blade tips during cutting at the initial stage of rotation. It was found that as wear progressed over time, the gap became larger, and the degree of improvement in turbo efficiency also decreased.

Effects of the Invention According to the impeller for an automobile turbocharger of the present invention, the part that comes into contact with the abradable thermal sprayed coating on the surface of the compressor housing, which is the mating material for gap adjustment, that is, the shoulder part, is made of FRM. Not only does it have excellent abrasion resistance, but it also has high deformation resistance, so there is a risk that the blade tips of the impeller may be worn or deformed when cutting the double thermal sprayed skin by rotating the impeller to adjust the gap. Therefore, the turbo efficiency can be reliably and sufficiently improved by adjusting the gap, and it also prevents the occurrence of a situation where the impeller wear progresses and the turbo efficiency decreases during use as a turbocharger. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an example of the essential parts of the impeller of the present invention, and FIG. 2 is a cross-sectional view showing the overall cross-blowing of an example of a turbocharger P- in which the impeller of the present invention is used. 4... Impeller, 4A... Wing tip part, 5...
compressor housing. Applicant Toyota Motor Corporation Agent Patent Attorney Yutaka 1) Hisashi Take (and 1 other person) Figure 1 44 /' Figure 2

Claims (1)

[Claims] In an automotive turbocharger impeller in which the gap between the impeller and the compressor housing is adjusted by rotating the impeller assembled to the compressor housing and cutting the abradable sprayed coating on the surface of the compressor housing with the tip of the impeller. An impeller for an automotive turbocharger, characterized in that the base material is made of a light alloy material, and the part that contacts the abradable thermal sprayed coating on the surface of the compressor housing is made of fiber-reinforced metal.