KR20110115513A - Turbocharger - Google Patents

Abstract

A shaft 20; 20 ′ supporting the blade wheels 21, 22; 21 ′, 22 ′, and one or more sliding bearings 30, 40 rotatably supporting the shaft within the bearing housing 13; 13 ′. A turbocharger (1; 1 ') comprising 30 ', 40 ' Members 31 ', 32'; 41, 42, wherein the sliding surface 32b '; 42b of one of the two bearing members is the same as that of the other bearing member of the two bearing members. The turbochargers 1, 1 ', which are formed softer than the sliding surfaces 31b'; 41b, are characterized in that the softer sliding surfaces are formed of graphite-containing iron-based material.

Description

Turbocharger {TURBOCHARGER}

The present invention relates to a turbocharger according to the preamble of claim 1.

Turbochargers of this type are known, for example, from DE 690 04 849 T2 and DE 10 2006 053 726 A1.

Other turbochargers with sliding bearings are for example disclosed in DE 196 41 673 A1.

In such turbochargers with sliding bearings the shafts supporting the blade wheels (turbine wheels, compressor wheels) are preferably made of steel and the bearing housing or central housing is made of iron-base alloys such as cast iron, in particular spheroidal graphite cast iron. do.

The sliding bearing in such a turbocharger can be formed as a radial bearing or a lateral bearing, as a thrust bearing or a longitudinal bearing and / or as a combination of a thrust bearing and a radial bearing.

The sliding bearings provided in such a turbocharger each comprise two bearing members with sliding surfaces which allow for relative rotational sliding movements. The sliding face of the bearing member of one of the two bearing members is formed softer than the sliding face of the other bearing member, which slidingly interacts with it.

Bearing members of the sliding bearing are usually made of the following materials:

-Bearing bush, bearing washer,

Profiled thrust bearings, counter thrust bearings: lead bronze

                                                       aluminum

                                                       Soft metal

-Shaft race, unprofiled thrust bearing: hardened steel

-Bearing housing, bearing body: spheroidal graphite cast iron

During operation of the turbocharger there should be a lubrication film between the sliding surfaces which interact in a sliding manner of the bearing members of the sliding bearing, which prevents metal contact between the sliding surfaces. In the absence of a lubrication membrane, the sliding surface of the soft bearing member must move relative to the sliding surface of the hard bearing member to provide specific emergency operating characteristics or emergency lubrication characteristics.

As the material for the soft sliding surface, a soft metal, preferably lead bronze, aluminum or white metal is used. Such material selection is a prior art since decades. For use in sliding bearings with low circumferential speeds and low loads, this material selection for soft sliding surfaces provides certain emergency operating characteristics.

In turbochargers with sliding speeds of 80 m / s or more during the rotary sliding motion of the sliding surfaces of the sliding bearings, the material selection according to the prior art no longer works completely. The use of prior art material selection in turbocharger sliding bearings presents the following disadvantages:

1. Certain emergency operating characteristics do not appear because the soft metal melts immediately due to its low melting point and loses its shape when the lubricating film is absent for a short time. As a result, the local, lubricating film-free area suddenly expands and immediately causes a complete failure of the sliding bearing.

2. The hard particles (eg chips, weld beads, waste gas residues, etc.) in the lubricating oil are embedded in the material of the soft sliding surface and act as an abrasive to the hard sliding surface (corresponding surface), thereby increasing wear.

3. In the case of rotating bearing washers or bearing bushes, the low strength of soft metals adversely affects the safety of the parts. Particularly, when the temperature rises, the strength of the parts decreases, so that the centrifugal force cannot be tolerated in some cases.

4. Different thermal expansion coefficients of the bearing material, the housing material and the shaft material can change the radial play relative to the stationary state during operation, especially in the case of radial sliding bearings. Due to this, the damping behavior of the radial bearing can change, which can lead to unstable operation or at least make the design of the radial sliding bearing difficult.

5. In particular, in the case of a composite bearing, in which soft metal is provided by melting or sputtering on a base body made of steel, incomplete bonding may result in separation of the soft metal layer, which may lead to bearing damage. .

In the case of thrust bearings with floating bearing washers, the problem disclosed in points 2, 3 and 4 can be solved by eliminating the disadvantages of soft metal bearings in part by the use of hardened and coated bearing washers. In this case, separation of the soft metal layer does not cause an immediate failure of the sliding bearing. The problem of lack of emergency operating characteristics, disclosed at point 1, can be reduced, but cannot be solved, because the normal coating is destroyed at temperatures above 400 ° C., so its friction reducing effect is abruptly reduced, which causes immediate bearing damage. Because.

The problem of the present invention is that in the turbocharger according to the preamble of claim 1, the sliding bearing (s) of the turbocharger have sufficient emergency operating characteristics in the absence of a lubrication membrane, which in some cases leads to a total failure of the sliding bearing. It is to provide a turbocharger that can prevent immediate bearing damage.

The problem is solved by a turbocharger according to claim 1. Improvements of the invention are set forth in the dependent claims.

According to the present invention there is provided a turbocharger comprising a shaft for supporting a blade wheel and at least one sliding bearing rotatably supporting the shaft in a bearing housing, the sliding bearing each sliding to allow relative rotational sliding motion. A two bearing members having a surface, the sliding surface of one of the two bearing members slidingly interacting with the sliding surface of the other bearing member of the two bearing members; It is formed softer than cotton. The turbocharger according to the invention is characterized in that the soft sliding surface is formed of graphite-containing iron-based material.

Preferably the shaft is made of steel and the bearing housing is made of iron-based material, such as spherical graphite cast iron.

By the inclusion of graphite, the soft sliding surface material comprises a high temperature resistant dry lubricant which significantly improves the emergency operating characteristics. The melting point of iron-based materials is much higher than that of soft metals. If the lubricating film is absent for a short time, the iron-base material of the soft sliding face does not melt and is only worn by the hard friction partner (other hard sliding face). Since bearing damages start at a locally limited point, sliding bearings are self-healing due to the wear of the material. Locally increased wear is seen in sliding bearings, but spontaneous bearing failures do not.

Since the iron-based material is much harder than the soft metal, less contaminant particles can be included into the soft sliding surface, which can cause the contaminated particles to be flushed from the sliding bearing by other structural measures (eg contaminated grooves). Stay in the sliding bearing much shorter. As a result, the sliding bearing of the turbocharger according to the invention has reduced wear compared to soft metal bearings.

According to an embodiment of the present invention, the graphite-containing iron-base material is formed of spherical graphite cast iron.

Spherical graphite cast iron can be processed very easily, so that the sliding bearing of the turbocharger according to the invention can be produced simply and at low cost.

According to an embodiment of the invention, the bearing member with the soft sliding surface is made entirely of graphite-containing iron-based material.

By the strength of the graphite-containing iron-base material, which is higher than the soft metal, and by a smaller decrease in its strength under temperature influences, the safety of the sliding bearings, in particular in rotating bearing washers (floating embodiment), is increased.

In other words, the sliding bearing according to the invention, in which the bearing member with the soft sliding face is made entirely of graphite-containing iron-base material, such as spherical graphite cast iron, can be designed as a single material bearing because of its better strength. It does not need to be implemented as a composite bearing. This not only reduces costs, but also reduces the risk of failure.

As mentioned above, the bearing housing of the turbocharger is usually made of cast iron, preferably spherical graphite cast iron. Therefore, since the material of the bearing member with the soft sliding face belongs to the same material family as the material of the bearing housing, the coefficient of thermal expansion of the bearing member with the soft sliding face corresponds to the coefficient of thermal expansion of the bearing housing. Due to this, the bearing play can be changed very little during operation, especially by radial sliding bearings, and the sensitivity of the sliding bearings to different lubricating oil temperatures is significantly reduced. The changed behavior must be taken into account in the design of cold play of the radial sliding bearing.

According to another embodiment of the present invention, a bearing member having a soft sliding surface is formed by the bearing housing.

According to another embodiment of the present invention, a bearing member having a soft sliding surface is formed integrally with the base body of the bearing housing or is mounted with the bearing housing part removably mounted to the base body of the bearing housing, such as a housing cover or a support body. It is formed integrally.

In this way, for example a separate bearing bush can be saved, a sliding bearing can be implemented in the turbocharger according to the invention simply, and therefore at low cost.

Preferably the sliding bearing of the turbocharger is formed as a radial bearing, thrust bearing or thrust-radial bearing. Preferably all bearings supporting the shaft in the bearing housing are formed as sliding bearings formed in accordance with the invention.

According to another embodiment of the invention the sliding bearing is formed as a rotating or floating sliding bearing or as a fixed or non-floating sliding bearing.

In other words, graphite-containing iron-based materials for soft sliding surfaces can be used for rotating and fixed radial bearings and rotating and fixed thrust bearings.

According to the present invention, a turbocharger is provided in which the sliding bearing (s) of the turbocharger have sufficient emergency operating characteristics, whereby immediate bearing damage accompanying the entire failure of the sliding bearing can be prevented in some cases.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional perspective view of a turbocharger according to an embodiment of the present invention.
2 is a cross-sectional perspective view of a turbocharger according to another embodiment of the present invention.
3 is a schematic cross-sectional view of a sliding bearing formed as a thrust bearing in accordance with an embodiment of the present invention.
4 is a schematic cross-sectional view of a sliding bearing formed as a radial bearing, in accordance with an embodiment of the invention.

1 is a cross-sectional perspective view of a turbocharger 1 according to an embodiment of the present invention.

The turbocharger 1 has a housing 10 made of spherical graphite cast iron. The housing 10 includes a turbine housing 11, a compressor housing 12, a bearing housing or a central housing 13 disposed between the turbine housing 11 and the compressor housing 12.

A shaft 20 made of hardened steel in the bearing housing 13 is rotatably supported by two sliding bearings 30, 30 each formed as a radial bearing and one or more sliding bearings 40 formed as a thrust bearing. , In the radial and axial directions.

Two sliding bearings 30, 30 each formed as a radial bearing in accordance with the embodiment of FIG. 1 are arranged laterally adjacent to the bearing housing 13, and the sliding bearing 40 formed as a thrust bearing is a compressor housing 12. Is disposed between the compressor bearing 12 and the sliding bearing 30 formed as a radial bearing adjacent to. As an alternative, thrust bearings may be arranged between the sliding bearings 30, 30.

The shaft 20 is mounted relatively rotatably thereon and is arranged in the turbine housing 11 with a first blade wheel (turbine blade wheel) 21 and a second blade wheel (compressor blade) disposed in the compressor housing 12. Wheel 22;

2 is a cross-sectional perspective view of a turbocharger 1 ′ according to another embodiment of the present invention.

The turbocharger 1 ′ has a housing 10 ′ made of spherical graphite cast iron, the housing 10 ′ having a turbine housing 11 ′, a compressor housing 12 ′, and the turbine housing 11 ′. And a bearing housing or central housing 13 'disposed between the compressor housing 12'.

A shaft 20 'made of hardened steel is formed in the bearing housing 13' by two sliding bearings 30 ', 30' each formed as a radial bearing, and one or more sliding bearings 40 'formed as a thrust bearing. It is rotatably supported and supported in radial and axial directions.

Two sliding bearings 30 'and 30', each formed as a radial bearing in accordance with the embodiment of FIG. 2, are disposed laterally adjacent to the turbine housing 11 'or the compressor housing 12', respectively, as thrust bearings. The formed sliding bearing 40 'is disposed in the center between two sliding bearings 30', 30 'each formed as a radial bearing. As an alternative, the thrust bearing can be arranged between the sliding bearings 30 ', 30'.

The shaft 20 'is mounted relative to it in a non-rotating manner and has a first blade wheel (turbine blade wheel) 21' disposed within the turbine housing 11 'and a second blade wheel disposed within the compressor housing 12'. Compressor blade wheel 22 ').

3 shows a schematic cross-sectional view of a sliding bearing 40 formed as a thrust bearing of the turbocharger 1 of FIG. 1.

The sliding bearing 40 formed as a thrust bearing has a first bearing member 41 formed as an annular projection (also called a track ring or race), and a second bearing member 42 formed as a thrust bearing washer floating-supported to the shaft 20. ), Wherein the first bearing member 41 and the second bearing member 42 are integrally formed with the sliding bearing 40.

The second bearing member 42 (thrust bearing washer) has an inner diameter 42a implemented as an oversize hole compared to the outer diameter 20a of the shaft 20.

The first bearing member 41 (annular projection of the shaft) is made of hardened steel like the shaft 20 and has a side sliding surface 41b. The side sliding surface 41b faces the first side sliding surface 42b of the second bearing member 42 (thrust bearing washer) made of the graphite-containing iron-base material (here, spherical graphite cast iron), so that the two sliding surfaces Faces 41b and 42b allow relative rotational sliding motion.

The second bearing member 42 also has a second side sliding surface 42c, which is directed toward the side sliding surface 13c formed in the shoulder of the bearing housing 13, so that the two sliding surfaces 42c, 13c) allows relative rotational sliding motion.

During operation of the turbocharger 1, between the side sliding surface 41b of the first bearing member 41 and the first side sliding surface 42b of the second bearing member 42, through an oil supply not shown. The lubricant film is formed in each of the bearing gaps 43 and 44 formed between the second side sliding surface 42c of the second bearing member 42 and the side sliding surface 13c of the bearing housing 13, thereby providing a shaft ( A first bearing member 41, which rotates with 20, is hydrodynamically axially supported by the second bearing member 42, and the second bearing member 42 is hydrodynamically axially supported by the bearing housing 13. Is supported in the direction.

Since the second bearing member 42 is made of spherical graphite cast iron, its first side sliding surface 42b faces it and is more than the side sliding surface 41b of the first bearing member 41 which interacts in a sliding manner with it. It is formed soft. Accordingly, the side sliding surface 41b of the first bearing member 41 in the absence of the lubricant film slides on the first side sliding surface 42b of the second bearing member 42 through solid friction or dry friction in emergency operation. In addition, the first side sliding surface 42b of the second bearing member 42 provides necessary emergency lubrication through graphite contained in the spherical graphite cast iron.

As shown in FIG. 3, the second bearing member 42 having a sliding surface 42b that is softer than the first bearing member 41 is made entirely of graphite-containing iron-base material (spheroidal graphite cast iron), so that the turbo There is no problem with regard to the strength of the second bearing member 42 rotating at about 1/2 shaft revolution during operation of the supercharger 1.

In a variant of the embodiment shown in FIG. 3 of a sliding bearing 40 formed as a thrust bearing of a turbocharger 1 according to the invention, a thrust bearing washer (second bearing member 42) according to another embodiment of the invention. ) May be omitted. In this case, the bearing housing 13 made of graphite-containing iron-base material (spheroidal graphite cast iron) has a softer sliding surface 13 than the first bearing member 41 and forms a second bearing member. In this case, the lateral sliding surface 41b of the first bearing member 41 is hydrodynamically supported axially on the lateral sliding surface 13c of the bearing housing 13 under sliding interaction.

According to this variant of the embodiment shown in FIG. 3, a bearing member having a softer sliding surface 13c is integrally formed with the base body of the bearing housing 13. Of course, according to another variant not shown, a bearing member having a softer sliding surface 13c may be formed integrally with a bearing housing part, for example, a housing cover, which is releasably mounted to the base member of the bearing housing 13. Can be.

As described with reference to FIG. 3 and variations thereof, the sliding bearing 40 formed as a thrust bearing can be formed as a rotating (floating) sliding bearing and a fixed (non-floating) sliding bearing.

FIG. 4 shows a schematic sectional view of the sliding bearings 30 ′, 30 ′ formed as radial bearings respectively of the turbocharger 1 ′ according to FIG. 2.

The sliding bearing 30 'formed as a radial bearing is a bearing firmly inserted into the longitudinal section of the shaft 20' as the first bearing member 31 'and the hole 13a' of the bearing housing 13 '. And a second bearing member 32 'formed as a bush.

The second bearing member 32 '(bearing bush) has an inner diameter 32a' defining a sliding surface 32b ', which is implemented as an oversize hole compared to the outer diameter 20a' of the shaft 20. .

The outer diameter 20a 'of the shaft is the sliding surface 31b toward the sliding surface 32b' of the second bearing member 32 'in the region of the first bearing member 31' (the longitudinal section of the shaft 20 '). '), The two sliding surfaces 31b' and 32b 'allow relative rotational sliding motion.

During operation of the turbocharger 1 ′, between the sliding face 31 b ′ of the first bearing member 31 ′ and the sliding face 32 b ′ of the second bearing member 32 ′, via an oil supply not shown, during operation of the turbocharger 1 ′. Since a lubricating oil film is formed in the bearing gap 33 'formed in the rotating shaft 20', the rotating shaft 20 'is hydrodynamically supported in the radial direction to the second bearing member 32' via the first bearing member 31 'formed by it. The second bearing member 32 'is supported by the bearing housing 13' in the radial direction.

Since the second bearing member 32 'is made of spherical graphite cast iron, the sliding surface 32b' is adapted to the sliding surface 32b 'of the first bearing member 31' formed by the shaft 20 '. It is formed softer than the sliding surface 31b 'facing and slidingly interacting with the sliding surface 32b'. Thus, the sliding surface 31b 'of the first bearing member 31' formed by the shaft 20 'in the absence of a lubricant film is slid of the second bearing member 32' through solid friction or dry friction in emergency operation. Sliding on the face 32b ', the sliding face 32b' of the second bearing member 32 'provides the necessary emergency lubrication through graphite contained in the spherical graphite cast iron.

In a variant of the embodiment shown in FIG. 4 of a sliding bearing 30 'formed as a radial bearing of a turbocharger 1' according to the invention, a bearing bush (second bearing member ( 32)) may be omitted. In this case, the hole 13a 'forming the sliding surface 13b' of the bearing housing 13 'made of graphite-containing iron-base material (spheroidal graphite cast iron) has a first bearing formed by the shaft 20'. Compared with the member 31 ', it has a softer sliding surface 13b' and forms a second bearing member. In this case, the sliding surface 31b 'of the first bearing member 31' formed by the shaft 20 'is hydrodynamically applied to the sliding surface 13b' of the bearing housing 13 'under sliding interaction. Supported in the radial direction.

According to this variant of the embodiment shown in FIG. 4, a bearing member having a softer sliding surface 13b ′ is integrally formed with the base body of the bearing housing 13 ′. Of course, according to another variant, not shown, the bearing member with the softer sliding surface 13b 'is integral with the bearing housing part, for example the housing cover, which is releasably mounted to the base member of the bearing housing 13'. It may be formed.

According to an unillustrated variant of the embodiment shown in FIG. 4, the hole 13a ′ of the bearing housing 13 ′ is embodied as an oversized hole relative to the outer diameter of the second bearing member 32 ′ (bearing bush). The second bearing member 32 'is floating supported in the hole 13a'. Another bearing gap is formed between the outer diameter of the second bearing member 32 '(to form another sliding surface) and the sliding surface 13b' formed by the hole 13a 'of the bearing housing 13', and the bearing In the gap, a lubricant film is formed through the oil supply portion during operation of the turbocharger 1 ', so that the rotating shaft 20' is connected to the second bearing member 32 'via the first bearing member 31' formed by it. Hydrodynamically supported in the radial direction, the second bearing member 32 'is hydrodynamically supported in the bearing housing 13'. According to another embodiment, two bearing bushes of the sliding bearings 30, 30 and 30 ′, 30 ′ may be integrated to form one part.

As shown in Fig. 4, according to this modification, the second bearing member 32 '(bearing bush) having the softer sliding surface 32b' is softer than the first bearing member 31 '. By being made of a base material (spheroidal graphite cast iron), there is no problem with regard to the strength of the second bearing member 32 'rotating at about 1/2 shaft revolution during operation of the turbocharger 1'.

As a result, as explained with reference to Fig. 4 and its variants, the sliding bearings 30 'and 30' respectively formed as radial bearings are formed as rotary (floating) sliding bearings and fixed (non-floating) sliding bearings. Can be.

Finally, the sliding bearings 30, 30 ′, 40, 40 ′ described in connection with FIGS. 1 to 4 are thrust-radial bearings, ie thrust bearings and radials, according to an unillustrated embodiment of the invention. It can be formed as a combination of bearings.

1, 1 ': turbocharger
10, 10 ': housing
11, 11 ': turbine housing
12, 12 ': compressor housing
13, 13 ': bearing housing
13a ': hall
13b ': sliding surface
13c: sliding surface
20, 20 ': shaft
20a, 20a ': outer diameter
21, 21 ': blade wheel
22, 22 ': blade wheel
30, 30 ': sliding bearing
31 ': bearing member
31b ': sliding side
32 ': bearing member
32a ': inner diameter
32b ': sliding surface
33 ': bearing gap
40, 40 ': sliding bearing
41: bearing member
41b: sliding surface
42: bearing member
42a: inner diameter
42b: sliding surface
42c: sliding surface
43: bearing gap
44: bearing gap

Claims (7)

A shaft 20; 20 ′ supporting the blade wheels 21, 22; 21 ′, 22 ′, and one or more rotatably supporting the shaft 20; 20 ′ in the bearing housing 13; 13 ′. As a turbocharger 1; 1 ′ comprising sliding bearings 30, 40; 30 ′, 40 ′,
The sliding bearings 30, 40; 30 ', 40' each have two bearing members 31 ', 32' having sliding surfaces 31b ', 32b'; 41b, 42b which allow relative rotational sliding movements; 41, 42),
The sliding surface 32b '; 42b of one bearing member of the two bearing members 31', 32 '; 41, 42 is formed of the two bearing members 31', 32 '; 41, 42. In the turbocharger of the other bearing member, which is formed to be softer than the sliding surface 31b '; 41b, which slidingly interacts with the sliding surface 32b'; 42b.
Turbocharger, characterized in that the softer sliding surface (32b '; 42b) is formed of graphite-containing iron-based material. 2. The turbocharger as claimed in claim 1, wherein the graphite-containing iron-based material is formed of spherical graphite cast iron. 3. Turbocharger according to claim 1 or 2, characterized in that the bearing member (32; 42) with the softer sliding surface (32b '; 42b) is made entirely of graphite-containing iron-based material. 4. The turbocharger as claimed in any one of the preceding claims, characterized in that the bearing member with the softer sliding surface is formed by the bearing housing (13; 13 '). 5. The bearing member according to claim 4, wherein the softer sliding surface bearing member can be formed integrally with the base body of the bearing housings 13; 13 ′ or can be loosened to the base body of the bearing housings 13; 13 ′. Turbocharger, characterized in that it is formed integrally with the bearing housing parts mounted. The turbocharger as claimed in claim 1, wherein the sliding bearings 30, 40; 30 ′, 40 ′ are formed as radial bearings, thrust bearings or thrust-radial bearings. . 7. Turbocharger according to any one of the preceding claims, characterized in that the sliding bearing (30, 40; 30 ', 40') is formed as a rotary sliding bearing or a fixed sliding bearing.

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