JPH048825A - Bearing device for turbocharger - Google Patents

Abstract

PURPOSE:To provide a bearing device with less noise cause by a rotary shaft or the like, by separately forming a bearing housing made of a material different from that of a casing, and by supporting the housing with the use of a support part which is provided on the compressor impeller side of the casing, in a cantilever-like manner. CONSTITUTION:An annular support part 23 is provided in a casing 7 on the compressor impeller 2 side, in stead of a conventional cylindrical part in the casing 7. Further, a cylindrical bearing housing 24 for rotatably supporting a rotary shaft by means of bearings 4, 5 is inserted in the support part 23, and a flange 25 is fixed by a bolt 11 so as to support the same in a cantilever- like manner. In this case, the bearing housing 24 is made of a material different from that of the casing 7, that is, made of a material such as aluminum, which has a vibration transmitting characteristic that is lower than a conventionally used steel group material. Further, the surface of the bearing housing 25 which mates with the bearings 4, 5 are surface-hardened by aluminized treatment or the like.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a bearing device for a turbocharger.

<Prior art> Conventionally, there are bearing devices for turbochargers of internal combustion engines as shown below (Japanese Patent Laid-Open No. 63-15
(See Publication No. 2716).

That is, as shown in FIG. 2, the rotating shaft 3 coaxially connects the turbine rotor 1 and the compressor impeller 2. It is supported by a cylindrical bearing housing 6.

The bearing housing 6 is fitted into a cylindrical portion 9 formed within the casing 7, and is fixed to the casing 7 at a flange 10 on the compressor impeller 2 side with bolts l.

The rolling bearings 4 and 5 have inner rings 4a and 5a and an outer ring 4, respectively.
b, 5b and balls 4c, 5c, and inner rings 4a, 5
The inner ring raceways 4d and 5d of a are arranged symmetrically opposite each other in the figure.

A thrust bearing portion 12 protruding toward the rotating shaft 3 is integrally formed on the inner periphery of the intermediate portion of the bearing housing 6 located on the outer periphery of the bearings 4 and 5 manufactured by various companies.

Outer spacers 14 and 15 are interposed between the thrust receiver section 12 and the outer rings 4b and 5b, respectively, and are biased toward the outer rings 4b and 5b by a compression spring 13. The relative position of the axis of rotation is regulated.

Further, the inner ring 4a is held between the inner spacer 16 and the thrust collar 17, and the inner ring 5a is held between the stepped portion 3a formed on the rotating shaft 3 and the inner spacer 16, so that positioning in the rotating shaft direction is performed.

A predetermined gap is formed between the bearing housing 6 and each outer ring 4b, 5b and outer spacer 14.15,
Pressure oil (lubricating oil) guided from the oil passage 18 into this gap
are the through holes 19a, 19b and the annular groove 20a.

20b, respectively.

In such a configuration, in the low speed range, the rolling bearings 4.5 are transferred, whereas in the high speed range, an oil film layer thick enough to support the rotating shaft 3 is formed in the gap, and the outer rings 4b, 5b
The outer spacers 14 and 15 rotate together with the rotating shaft 3 at high speed.

<Problems to be Solved by the Invention> Incidentally, in such a conventional bearing device, the inner circumferential surface of the cylindrical portion 9 of the casing 7 comes into contact with almost the entire outer circumferential surface of the bearing housing 6, and the bearing Because of the structure in which the housing 6 is supported in the radial direction, and the flange 10 is fixed to the casing 7 for axial support,
The excitation force due to whirling of the rotating shaft 3 is directly transmitted to the casing 7 main body via the bearing housing 6, and strongly (excites) the turbine housing 22 assembled thereto via the casing 7.

If the excitation force applied to the turbine housing 22 is large, there is a problem in that the noise of the turbocharger transmitted to the outside of the engine becomes large.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 63-239315, there is a bearing housing supported in a cantilevered manner, which makes it difficult for vibrations to be transmitted to the turbine housing to some extent, but the bearing housing and the casing are Because it is a one-piece structure, it is difficult to select a material that has both vibration damping characteristics and heat-resistant strength.
Furthermore, there is also the problem that the use of such materials significantly increases costs.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a bearing device for a turbocharger that generates less noise caused by a rotating shaft or the like.

<Means for Solving the Problems> For this reason, the present invention rotatably supports a rotating shaft that transmits rotation of a turbine rotor to a compressor impeller via a bearing by a substantially cylindrical bearing housing provided in a casing. In the bearing device for a turbocharger, the bearing housing is formed separately from the casing using a different material, and is supported in a cantilevered manner by a support portion provided on the compressor impeller side of the casing.

Here, it is preferable that the bearing housing is formed of a material with low vibration transmission properties, and that a surface of the bearing housing that comes into contact with the bearing is surface hardened.

(Function) According to the above configuration, the bearing housing that supports the rotating shaft is supported in a cantilever state by the support part on the compressor impeller side of the casing, so the vibration of the rotating shaft transmitted to the bearing housing is It is transmitted to the casing only from the part on the compressor impeller side that is supported in this state, and is less likely to be transmitted to the turbine housing side.

Furthermore, since the bearing housing is formed separately from the casing using a different material, it is possible to make a difference in vibration transmission properties between the bearing housing and the casing.

In particular, if the bearing housing is molded from a material with low vibration transmission properties such as aluminum, the vibrations transmitted to the casing can be further reduced, and the surface of the bearing housing that contacts the bearing can be hardened by, for example, aluminization treatment. This can compensate for the lack of hardness due to the bearing housing being made of a material with low vibration transmission properties.

<Example> An embodiment of the present invention will be described below with reference to FIG.

Incidentally, the same parts as in the conventional example are given the same reference numerals, and the description thereof will be omitted.

The conventional cylindrical part (9 in FIG. 2) of the casing 7 is eliminated, and instead an annular support part 23 is formed on the compressor impeller 2 side via the connecting part 8.

Then, a substantially cylindrical bearing housing 24 that rotatably supports the rotating shaft 3 via a bearing 4.5 is fitted into the support portion 23 of the casing 7, and the flange 25 is attached to the bolt 1.
1 and support it in a cantilevered state.

Note that the lubricating oil is supplied through an oil passage 2 provided in the casing 7.
6. Oil passage 27 and through holes 19a, 19b provided inside bearing housing 24, annular groove 208.20
b to be introduced into the bearings 4 and 5.

Here, the bearing housing 24 is molded separately from the casing 7 using a different material.
For example, aluminum is used, which has lower vibration transmission properties than conventionally used iron-based materials.

In order to ensure the hardness of the surfaces on the side of the bearings 4 and 5, the surfaces of the bearing housing 25 that are in contact with the bearings 4 and 5 are surface hardened by, for example, aluminizing treatment.

With this configuration, the bearing housing 24 is cantilevered by the casing 7 only at the locations of the two compressor impellers, so only these locations are in contact with the casing 7, so that the vibration transmitted to the casing 7 is reduced. As the force decreases, the transmission path of the excitation force to the turbine housing 22 becomes longer and more complicated: rotating shaft 3 → bearing housing 24 → flange 25 → support part 23 → casing 7 → turbine housing 22. The vibrations transmitted to the vehicle are significantly reduced, and the noise is also reduced.

Further, since the bearing housing 24 itself is formed of a material with low vibration transmission properties, even if the bearing housing 24 has the same structure, it is difficult to transmit vibrations, and in particular, if it is made of aluminum, the weight can be reduced.

Further, the surfaces of the bearing housing 24 that come into contact with the bearings 4 and 5 are surface hardened to ensure hardness.

Furthermore, when casting the casing 7, the core that was conventionally required is significantly simplified, the castability is greatly improved, and the cost is reduced.

Since there are few contact points between the casing 7 and the bearing housing 24, heat is not directly transferred from the high-temperature casing 7 to the rotating shaft 3, so the bearing temperature decreases and the bearing life is extended.

Furthermore, since the bearing temperature is lowered, the bearing material can be changed to a cheaper one, and the unit price of the bearing can be significantly lowered.

Also, since the temperature of the bearing housing 24 also decreases,
The material of the bearing housing 24 can be aluminum, as described above.

In addition, although the embodiment shows an example using a rolling bearing, the same effect can be obtained for a shaft system using a sliding bearing using a floating metal.

<Effects of the Invention> As explained above, according to the present invention, the bearing housing is supported in a cantilevered manner by the support portion on the compressor impeller side in the casing, thereby reducing contact between the casing and the bearing housing, and Since the contact is made at a distance from the turbine housing, the transmission of vibration to the casing is reduced, and the transmission of vibration to the turbine housing is further damped.

As a result, noise caused by whirling of the rotating shaft can be reduced.

Furthermore, since the bearing housing is made of a material with low vibration transmission properties, the transmission of vibration can be further reduced, and since the surface of the bearing housing that contacts the bearing is surface hardened, hardness can be ensured.

Furthermore, the castability of the casing is improved, the selectivity of the material from which the bearing housing is formed is improved, the bearing life is extended, and the economical efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a turbocharger showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional turbocharger. 1... Turbine rotor 2... Compressor impeller 3... Rotating shaft 4, 5... Bearing 7.
...Casing 22...Turbine housing
23...Supporting part 24...Bearing housing 25...Flange patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima

Claims (2)

[Claims] (1) A bearing device for a turbocharger in which a rotating shaft that transmits the rotation of a turbine rotor to a compressor impeller is rotatably supported via a bearing by a substantially cylindrical bearing housing provided in a casing. A bearing device for a turbocharger, characterized in that a housing is formed separately from the casing and made of a different material, and is supported in a cantilevered state by a support portion provided on a compressor impeller side of the casing. (2) The bearing device for a turbocharger according to claim 1, wherein the bearing housing is formed of a material with low vibration transmission properties, and a surface of the bearing housing that comes into contact with the bearing is surface hardened.