JP3397841B2 - Turbocharger bearing device with split bearing inner ring made of different materials - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger bearing device having a split bearing inner ring made of different materials.

[0002]

2. Description of the Related Art In general, in order to improve responsiveness, a turbocharger designer has proposed a structure in which a bearing including a roller member is used to support a shaft having a turbine wheel and a compressor wheel. These bearings include an inner ring, an outer ring and a rolling member disposed between the inner and outer rings. The inner ring of the bearing is mounted directly on the shaft to give the rotor system high radial strength and high bending strength. Such a turbocharger is disclosed in U.S. Pat. No. 5,055,009, in which an axially spaced stepped bearing bearing surface is provided on the shaft, which bearing bearing surface. It abuts the corresponding surface on the inner ring. The bearing inner ring is divided into a plurality of segments, with the bearing inner ring closest to the turbine wheel being made of a relatively expensive refractory material, while the other segments are made of conventional materials.

[0003]

The prior art of this type provides a relatively large contact surface between the bearing inner ring and the shaft, which results in a large heat transfer path from the turbine wheel to the central housing. Therefore, there is a problem that large heat conduction occurs. Furthermore, the interface portion between the segments and the adjacent segment portion must be supported by the same diameter shaft. In order to prevent misalignment or cogging phenomenon between segments, it is necessary to manage extremely strict tolerances, resulting in high cost.

SUMMARY OF THE INVENTION The object of the present invention, however, is to solve the above-mentioned problems and to completely eliminate the bearing bearing surface for bearing the interface part, so that a strict tolerance is provided in the interface part between the segments of the bearing inner ring. The bearing device is configured to minimize heat conduction without managing tolerances. In this case, two segments made of different materials are joined together via an interface, preferably by spin welding or inertia welding. At this time, the inertia welding rotates one of the two members with respect to the other member, and the frictional heat generated between these members causes the material to soften the interface portion.
A configuration may be taken in which the joining is achieved.

[0005]

According to the present invention, a housing having a pair of ends, a shaft arranged in the housing, and a shaft mounted in one end of the shaft so as to be rotatable together in the housing. Compressor wheel, a turbine wheel rotatably mounted in the housing at the other end of the shaft, an air supply device for supplying air through the compressor wheel, and an exhaust gas for supplying exhaust gas through the turbine wheel. It is equipped with an air compressor that rotates the turbine wheel to rotate the shaft and the compressor wheel mounted on the shaft to compress the air passing through the compressor wheel, and a bearing device that rotatably mounts the shaft to the housing. The bearing device has a bearing outer ring and a bearing inner ring and a bearing inner And a ball bearing member for supporting the bearing outer ring are included on the shaft, and a pair of bearing bearing surfaces formed on the bearing inner ring and axially separated from each other are in contact with the bearing bearing surface on the shaft and Bearing inner ring is supported, the bearing inner ring is composed of a pair of segments, one segment supports one end of the shaft, the other segment supports the other end of the shaft, one segment is heat resistant Made of a flexible material, and the other segment made of a normal low temperature material, the two segments abutting each other and joining each other through the interface portion, the interface portion and the segment adjacent to the interface portion. The part is not supported by Shaft and works together with Shaft. Is by connexion achieved Tabochiyajiya driven by provided comprising an exhaust gas so as to form an air gap.

[0006]

According to the turbocharger bearing device of the present invention having the above-described structure, bearing materials made of different materials can be butt-welded extremely easily.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, an exhaust gas driven turbocharger 10 includes a central housing 12, a turbine housing 14 fixed to the central housing 12 by bolts 16, and a central housing 12 facing the turbine housing 14. A compressor housing 18 fixed via a retaining ring 20 is included at the end of the housing. The inlet 22 of the compressor housing 18 is connected to a source of filtered outside air, while the outlet spiral 24 of the compressor housing 18 is connected to the engine intake manifold. The inlet swirl 26 of the turbine housing 14 is connected to the exhaust manifold of the engine, thereby attaching the turbocharger 10 to the engine, while the outlet 28 of the turbine housing 14 is connected to the exhaust system of the vehicle.

Turbine wheel 30 is mounted at one end of a shaft 32 that extends into turbine housing 14. The turbine wheel 30 includes turbine blades 34, and the exhaust gas flows from the introduction spiral portion 26 through the turbine blades 34 to the discharge portion 28, whereby the turbine wheel 30 is rotated, and accordingly, the shaft 32 is changed. Is rotated. A shroud 36 of known construction is disposed between the turbine wheel 30 and the central housing 12 to prevent heat transfer therebetween. Inside the compressor housing 18, the compressor wheel 30 is mounted on the other end of the shaft 32, which has the turbine wheel 30 mounted on one end. The air introduced from the introduction portion 22 is made to flow through the blade portions 40 of the compressor wheel 38. By rotating the compressor wheel 38, the air is compressed and the compressed air is sent into the lead-out spiral section 24.

A shaft 32 is rotatably mounted in a bearing support 44 of the bearing cartridge 42, the bearing support 44 itself preferably being in the central housing 1.
It is provided so as to form a part of 2. Engine cooling fluid is introduced into the central housing 12 via a suitable cooling fluid passage 46 formed in the central housing 12. On the other hand, the lubricating oil is transferred to the bearing cartridge 42 through the oil introduction passage 48 and the oil discharge passage 50 of the central housing 12.
Be introduced to. An enlarged hub portion 52 is provided near the end of the shaft 32, and the turbine wheel 30 is mounted thereon. In this case, the expanded hub portion 52
A turbine seat portion 54 is provided in the. And the sealing portion 56
Are provided to prevent leakage into the compressor housing 18.

Referring to FIG. 2, the bearing outer ring 58 of the bearing cartridge 42 is the bearing support 4.
It is received in the cavity 60 of four. Further, the bearing outer ring 58 is configured as a solid and non-divided member, and includes a first set of ball bearing members 62 circumferentially spaced from the bearing outer ring 58 and a robust second circumferentially spaced ball bearing member 62. Of the ball bearing members 64 are mechanically connected. The ball bearing members 62 and 64 themselves may be formed by a known structure, and the ball bearing members 62 and 64 rotatably support the bearing inner ring 66 on the bearing outer ring 58. The ball bearing members 62 and 64 themselves may be ball bearing materials known to those skilled in the art.

The bearing inner ring 66 is composed of two segments 68,70. One segment 68 extends inward from the compressor-side other end of the shaft 32, and the other segment 70 extends toward the segment 68 from one end of the shaft 32 where the turbine wheel 30 is mounted. Segment 70 is M50
Made of relatively expensive and heat resistant materials such as steel. This is because the turbine side of the turbocharger has a relatively high temperature. In particular, the heat received on the turbine side after the engine is stopped is transferred to the bearing inner ring 66 via the shaft 32. On the other hand, this heat is generated by the turbine wheel 30.
Diverge as a function of distance from. Therefore, segment 7
The length of 0 is set according to the temperature gradient in the bearing inner ring 66. At this time, the segment 70 is provided long enough to dissipate heat sufficiently.
The temperature at the left end (in FIG. 2) of the is reduced to a sufficiently low level through the low temperature steel of the bearing segment 68 material.

An interface portion 72 is joined to the joining ends of the segments 68 and 70, and both are welded to each other.
It is fixed through 4. In this case, the size of the welded portion 74 is exaggerated in FIG. 2 to facilitate understanding. Welded part 74
Is preferably such that the frictional heat generated by rotating one of the segments 68, 70 relative to the other causes the material to soften at the interface 72, thereby forming the weld 74. It can be formed by the inertia welding method. The bearing inner ring 66 can also be machined as if made of a uniform material. A bearing bearing surface 76 extending across a part of the segment 70 is provided at one end of the shaft 32 on the turbine side. A bearing bearing surface 78 is formed on the segment 70 so as to face and abut the bearing bearing surface 76. The shaft 32 has another bearing bearing surface 80.
The bearing bearing surface 80 is capable of abutting against the bearing bearing surface 82 formed on the segment 68. The segments 68, 70 between the bearing bearing surfaces 82, 78 and the interface portions 72, 74 are the shaft 3
It is not supported by 2 and is provided so as to cooperate with the outer circumferential surface 84 of the shaft 32 to form a gap G therebetween. The dust gap G prevents heat conduction between the shaft 32 and the bearing inner ring 66 on which the relatively high temperature turbine wheel 30 is mounted. Therefore, the hot turbine wheel 38 and the bearing inner ring 66 are
The direct heat conduction path between the bearing bearing surfaces 76, 78
It is restricted to only the path through the metal contact between. What is important here is that the axial length of the bearing bearing surfaces 76, 78 should be as short as possible while still providing a predetermined radial and bending strength of the bearing cartridge.
The bearing inner ring 66 and the ends of the shafts in which the bearing bearing surfaces 80, 82 are formed are adjacent to the cooler compressor wheel, the length of these bearing bearing surfaces being not critical but the bearing bearing surfaces. 8
0, 82 are made considerably longer than the bearing bearing surfaces 76, 78. The gap G is the bearing bearing surface 76, 80.
Extending entirely through the bearing inner ring 66 between, there is no direct external heat transfer path from the shaft 32 to the bearing cartridge, and the air gap G acts as an insulation.

[0013]

As is apparent from the above, according to the present invention, the tight tolerances required for the device between the cooperating bearing bearing surfaces for bearing the joint ends of the segments 68, 70 can be eliminated by the present invention. . Thus, according to the present invention, tight manufacturing tolerances can be minimized and also the heat transfer path between the turbine wheel and the inner race can be minimized. Moreover, in the conventional apparatus, the inner race is integrally manufactured, but the bearing designer needs to manufacture each member from a relatively expensive heat-resistant material, which causes a problem. Bearing bearing surface 7 with sufficient longitudinal strength
6 and 78, the maintenance is easy, and the inner race can be made of a relatively inexpensive low temperature material so that the cost can be minimized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an exhaust gas driven turbocharger using a bearing arrangement in accordance with the present invention.

FIG. 2 is a partially enlarged view of a portion surrounded by a dotted line in FIG.

[Explanation of symbols]

10 Turbocharger 12 Central housing 14 Turbine housing 16 volts 18 Compressor housing 20 retaining ring 22 Introduction 24 Derived spiral part 26 Introductory spiral part 28 Derivation part 30 turbine wheels 32 Shaft 34 turbine blades 36 shroud 38 Compressor Wheel 40 blade 42 bearing cartridge 44 Bearing support 46 Coolant passage 48 oil introduction path 50 oil outlet 52 Expansion hub 54 Turbine seat 56 Seal 58 Bearing outer ring 60 cavity 62 ball bearing members 64 ball bearing members 66 Bearing inner ring 68 segments 70 segments 72 Interface section 74 Weld 76 Bearing support surface 78 Bearing support surface 80 Bearing support surface 82 Bearing support surface 84 outer circumferential surface

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Claims (5)

(57) [Claims] 1. A housing having a pair of ends, a shaft arranged in the housing, a compressor wheel mounted at one end of the shaft so as to be rotatable in the housing, and rotatable in the housing. The turbine wheel mounted on the other end of the shaft, the air supply device for supplying air through the compressor wheel, the exhaust gas supplied through the turbine wheel to rotate the turbine wheel, and the shaft and shaft were mounted on the shaft. An air compression device that rotates the compressor wheel to compress the air that passes through the compressor wheel, and a bearing device that rotatably mounts the shaft to the housing,
The bearing device includes a bearing outer ring, a bearing inner ring, and a ball bearing member that supports the bearing outer ring on the bearing inner ring.
A pair of bearing bearing surfaces formed axially spaced on the bearing inner ring abut the bearing bearing surface on the shaft to support the bearing inner ring on the shaft, and the bearing inner ring is composed of a pair of segments. , One segment bearing one end of the shaft, the other segment bearing the other end of the shaft, one segment made of heat resistant material and the other segment made of normal low temperature material. The two segments abut each other and are joined to each other via the interface portion, and the interface portion and a portion of the segment adjacent to the interface portion are not supported by the shaft and cooperate with the shaft to form a gap therebetween. Turbocharger driven by exhaust gas provided to form Ya. 2. The turbocharger of claim 1 wherein the segments are joined together at the interface portion of the weld. 3. The turbocharger of claim 1, wherein the segments are joined together at an interface portion by an inertia weld. 4. The ball bearing member includes a first set of members and a second set of members axially spaced from the first set of members, wherein the bearing outer ring is a robust member. The turbocharger according to claim 1, wherein 5. The ball bearing member includes a first set of members and a second set of members axially spaced from the first set of members, wherein the bearing outer ring is a robust member. The turbocharger according to claim 3, wherein