JP2009270612A - Bearing structure of turbocharger - Google Patents

Abstract

[PROBLEMS] To prevent transmission of rotational vibration and suppress noise even when an oil film is not sufficiently formed by a structure having no problem in durability.
In a turbocharger bearing structure using a rolling bearing, a bearing holder that holds an outer ring of a pair of bearings 20 and 21 and is supported in a floating state via a clearance b formed between the bearing housing 10 and an oil film. (Oil film damper) 30 is provided. A flange portion 60 is provided on the bearing holder 30, and the flange portion 60 is sandwiched and fixed in the bearing housing 10 so as not to cause an axial misalignment in the bearing holder 30. Then, elastic portions 61 and 62 that are flexible in the radial direction are formed at both ends of the flange portion 60.
[Selection] Figure 1

Description

  The present invention relates to a turbocharger bearing structure, and more particularly to a turbocharger bearing structure in which a rotating shaft is supported by a rolling bearing.

  In a turbocharger using a rolling bearing, a rotating shaft that connects a turbine wheel and a compressor wheel is supported by a rolling bearing, and an outer ring of the rolling bearing is held by a sleeve-shaped bearing holder (oil film damper). The bearing holder is supported in a floating state by providing a clearance with the inner surface of the bearing housing and forming an oil film in the clearance. During operation, the bearing holder does not come into contact with the bearing housing, and the vibration transmission of the bearing is suppressed by the damping effect due to the oil film formation.

  When the engine is started and stopped, the oil film may not be formed satisfactorily for reasons such as a delay in oil pressure increase or a decrease in oil pressure. In this case, when the bearing holder made of metal and the bearing housing are in direct contact, rotational vibration is transmitted to the outside, and noise is generated.

In order to prevent this, a method of providing a vibration damping ring made of a resin such as rubber around the bearing holder is known (see Patent Document 1). When the oil film is not sufficiently formed, the damping ring comes into contact with the bearing housing, thereby preventing contact with the bearing housing and obtaining a damping effect.
Japanese Utility Model Publication No. 5-12632

  When a resin damping ring as in Patent Document 1 is provided, there is a problem of heat resistance, and expansion occurs while exposed to high-temperature lubricating oil, resulting in a reduced damping function. Use of such a resin member causes a problem of durability, and rotation vibration is transmitted to the outside due to deterioration, and noise may be generated.

  A bearing structure for a turbocharger according to the present invention includes a rolling bearing that supports a rotating shaft, and a bearing holder that holds an outer ring of the rolling bearing and is provided with a bearing housing and an oil film forming gap. For example, a pair of rolling bearings are arranged on the turbine side and the compressor side, and a sleeve-shaped metal bearing holder holds the pair of bearing outer rings. And at least one part structure of a holder is comprised as an elastic part flexible in radial direction, It is characterized by the above-mentioned.

  In the present invention, a vibration damping member or the like is not attached to the bearing holder, but at least a part of the structure of the bearing holder itself has a structure having elastic performance. The elastic portion in contact with the oil film bends in the radial direction when rotating and vibrates, and a large vibration damping effect is added to the damping function by forming the oil film. Even when the oil film is not sufficiently formed, the elastic portion is bent in the radial direction to produce a vibration damping effect and no noise is generated.

  Since the bearing holder has a structure having an elastic portion, there is a possibility that the shaft center of the bearing holder is displaced during rotation of the bearing holder and the rotation function is impaired. In order to prevent this, it is desirable to provide a flange portion in the bearing holder and fix the flange portion in contact with the bearing housing so as not to cause an axial misalignment between the bearing housing and the bearing holder. In order to facilitate assembly, for example, the flange portion may be sandwiched and fixed by a retainer fixed to the bearing housing.

  When the flange portion is fixed in contact with the bearing housing, the rigidity in the vicinity of the flange portion is increased and vibration is easily transmitted. In order to suppress this, it is desirable to make the elastic part adjacent to the flange part and improve the damping effect around the flange part.

  As the elastic part, for example, an elastic part formed between the outer rings of a pair of rolling bearings and having a plurality of holes along the circumferential direction can be configured. This reduces the strength of the bearing holder and exhibits elastic performance. In order to increase the damping effect by further bending the elastic portion, the thickness of the elastic portion may be made as thin as possible, for example, it may be made thinner than the thickness of the portion other than the elastic portion between the outer rings.

  According to the present invention, due to the structure having no problem with durability, transmission of rotational vibration can be prevented and noise can be suppressed even when the oil film is not sufficiently formed.

  Below, the bearing structure of the turbocharger which is embodiment of this invention is demonstrated with reference to drawings.

  FIG. 1 is a schematic cross-sectional view of a turbocharger rolling bearing structure according to this embodiment. FIG. 2 is a schematic perspective view of the bearing holder.

  The turbocharger (exhaust turbine supercharger) 100 includes a turbine wheel (not shown) that is rotationally driven by exhaust gas from the engine, and a compressor wheel (not shown) that compresses intake air and sends the compressed air to the engine. The turbine wheel and the compressor wheel are connected by a rotating shaft 50. The rotating shaft 50 is housed in the bearing housing 10 and is pivotally supported by a pair of rolling bearings 20 and 21.

  The inner rings 24 and 25 of the rolling bearings 20 and 21 are fixed to the rotary shaft 50 via spacers 90. On the other hand, the outer rings 22, 23 of the rolling bearings 20, 21 are held by a sleeve-shaped metal bearing holder 30, and the outer rings 22, 23 are fitted into the holding portions 37, 38 of the bearing holder 30. When the rotary shaft 50 is rotated by turbocharging, the bearing holder 30 is coaxially supported in a floating state via the gap b formed with the bearing housing 10 and the oil film.

  As shown in FIG. 2, the bearing holder 30 has a disk-like flange portion 60 near the center along the axial direction, and abuts against the stepped portion 10 </ b> A of the bearing housing 10 (see FIG. 1). On the other hand, a cylindrical retainer 80 fixed to the bearing housing 10 by a bolt (not shown) has a cylindrical portion 82 that extends in the axial direction with a clearance b from the bearing holder 30, and the cylindrical portion 82 is a bearing. A part of the inner surface of the housing 10 is formed. The flange portion 60 is sandwiched between the cylindrical portion 82 and the stepped portion 10 </ b> A of the bearing housing 10 and fixed in contact therewith.

  On both sides of the flange portion 60, elastic portions 61 and 62 having flexibility in the radial direction are formed. As shown in FIG. 2, a plurality of rectangular holes 61 </ b> A and 62 </ b> A are formed at predetermined intervals along the circumferential direction in the elastic portions 61 and 62 that are part of the structure of the metal bearing holder 30. And the thickness t1 of the elastic parts 61 and 62 is thinner than the thickness t2 of the part between the outer rings 22 and 23 of the holding parts 37 and 38 (see FIG. 1).

  With such a thin wall thickness and the formation of the plurality of holes 61A, 62A, an elastic structure with low strength and flexibility in the radial direction is created. Here, the holes 61A and 62A are formed by cutting out a thin metal member at a plurality of locations along the circumferential direction. The elastic portions 61 and 62 are disposed between the holding portions 37 and 38 and the flange portion 60, and the metal elastic portions 61 and 62, the holding portions 37 and 38, and the flange portion 60 are integrated into a bearing. A holder 60 is configured.

  On the compressor side of the bearing housing 10, the lubricating oil is supplied to the gap b in the bearing housing 10 through the lubricating oil supply hole 11 and the oil passage 81 of the retainer 80. On the other hand, on the turbine side, the lubricating oil is supplied to the gap b through the lubricating oil supply hole 12.

  Grooves 31 and 32 are formed in the holding portions 37 and 38 of the bearing holder 30 along the circumferential direction, oil holes 35 and 36 are formed in the grooves 31 and 32, and oil supply holes 33 and 34 are further formed. ing. When the lubricating oil is supplied to the gap b in the bearing housing 10, it flows out through the oil holes 35 and 36 and the oil supply holes 33 and 34 toward the balls 26 and 27 of the bearings 20 and 21. As a result, the bearings 20 and 21 are cooled.

  Lubricating oil supplied to the compressor side of the bearing housing 10 is gravity discharged from the discharge hole 39, and lubricating oil supplied to the turbine side is gravity discharged through the discharge hole 40. A shaft seal 51 is provided on the turbine side of the rotating shaft 50.

  Hereinafter, the damping action will be described. During operation, the oil film is formed in the gap b, so that the oil film damper function is exhibited and rotational vibration is suppressed. Furthermore, a further damping effect is exhibited by the elastic action in the radial direction of the elastic portions 61 and 62 when rotating and vibrating, and the rotating vibration reducing effect is improved.

  Even in an operating state where the oil film is not sufficiently formed such as when the engine is started or after the engine is stopped, the elastic portions 61 and 62 improve the vibration damping effect, so that the transmission of rotational vibration can be suppressed. In particular, since the elastic portions 61 and 62 having a damping effect are formed on both sides of the flange portion 60 having high rigidity and strength, it is possible to prevent the damping effect from being lowered around the flange portion 60 and to transmit vibrations through the flange portion 60. Suppress. In this way, the damping performance is improved only by the metal bearing holder 30, and there is no need to worry about durability when using a resin member.

  Further, the flange portion 60 is sandwiched and fixed with respect to the bearing housing 10, and is firmly fixed so that the bearing holder 30 is coaxially disposed with respect to the bearing housing 10. Therefore, the flange part 60 is positioned in the axial direction and the rotation is also stopped. As a result, even in the structure having the flexible elastic portions 60 and 61, the bearing holder 30 is not inclined with respect to the shaft, and the shaft center is not displaced.

  Further, when the flange portion 60 is fixed in contact, the bearing holder 30 does not come into contact with the bearing housing 10 in a state where the oil pressure is reduced and an oil film is formed or not sufficiently formed. Further, even if the oil film formation is insufficient, the contact between the bearing holder 30 and the bearing housing 10 is prevented. In order to prevent the end portions of the holding portions 37 and 38 of the bearing holder 30 from coming into contact with the bearing housing 10 and to suppress vibration transmission of the bearings 20 and 21, the flange portion 60 hits the bearings 20 and 21 at the same distance. In the vicinity of the center position away from the bearings 20 and 21.

  As described above, according to the present embodiment, in the turbocharger bearing structure using the rolling bearing, the bearing holder 30 holds the outer ring of the pair of bearings 20 and 21, and the clearance b between the bearing housing 10 and the oil film is formed. And is supported in a floating state. The bearing holder 30 is provided with a flange portion 60, and the flange portion 60 is sandwiched and fixed with respect to the bearing housing 10 so that the shaft center of the bearing holder 30 does not shift. Then, elastic portions 61 and 62 that are flexible in the radial direction are formed at both ends of the flange portion 60.

  The elastic portions 61 and 62 may be configured to be easily bent in the radial direction in contact with the oil film, and may be formed so as to reduce the strength as much as possible.

  The flange portion 60 may be fixed in contact with the bearing housing 10 by means other than scissor fixing. Or you may fix so that the movement to a radial direction is possible.

  The flange portion 60 may not be firmly fixed, but may be movable only in the radial direction. In addition, the flange portion 60 may not be provided on the bearing holder 30, and the position variation may be allowed to some extent so as to suppress rotation by applying a pin protruding from the bearing housing to the bearing holder as in the past. Even in this case, due to the bending of the elastic portion, the damping function is exhibited even if the oil film is not sufficiently formed, and rotational vibration is suppressed.

  When the inner bearing holder is configured without providing the flange portion, two bearing holders may be provided and a spring may be disposed between them.

It is a schematic sectional drawing of the rolling bearing structure of the turbocharger which is this embodiment. It is a typical perspective view of a bearing holder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bearing housing 20, 21 Rolling bearing 22, 23 Outer ring 30 Bearing holder 37, 38 Holding part 50 Rotating shaft 60 Flange part 61, 62 Elastic part 80 Retainer 82 Cylindrical part 100 Turbocharger

Claims (6)

A rolling bearing that supports the rotating shaft;
Holding an outer ring of the rolling bearing, and a bearing holder disposed in a floating state via a bearing housing and an oil film forming gap;
A turbocharger bearing structure, wherein at least a part of the structure of the bearing holder is configured as an elastic part having flexibility in a radial direction. The bearing holder has a flange portion;
2. The turbocharger bearing structure according to claim 1, wherein the flange portion is fixed in contact with the bearing housing so that an axial misalignment between the bearing housing and the bearing holder does not occur. The turbocharger bearing structure according to claim 2, wherein the flange portion is sandwiched and fixed. 4. The turbocharger bearing structure according to claim 2, wherein the elastic portion is adjacent to the flange portion. 5. 5. The turbocharger bearing structure according to claim 1, wherein the elastic portion is formed between outer rings of a pair of rolling bearings and has a plurality of holes along a circumferential direction. 6. The turbocharger bearing structure according to claim 5, wherein a thickness of the elastic portion is thinner than a thickness of a portion other than the elastic portion between the outer rings.

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