JP2009203846A - Ball bearing arrangement for turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a band-shaped wear mark from being generated on a ball of an angular ball bearing in a turbocharger bearing device even if the temperature rises, and to prevent or suppress the generation of abnormal noise.
A turbocharger bearing device 1 of the present invention includes a pair of angular ball bearings 2a and 2b. The ball bearings 2a and 2b are a pair of inner ring raceways 3a and 3a separated in the axial direction of a rotary shaft 32. Between the inner ring 3 on the rotating shaft side, the pair of outer rings 4, 4 on the housing side having the outer ring raceways 4a, 4a facing the inner ring raceways 3a, 3a, and between the inner ring raceways 3a, 3a and the outer ring raceways 4a, 4a. And a plurality of balls 5 interposed so as to roll freely in a state of zero or a positive clearance. Then, by providing the pressing member 10 that thermally expands at a high temperature and presses the outer ring 4 of one angular ball bearing 2a toward the other angular ball bearing side 2b in the axial direction, the rotary shaft 32 is thermally expanded due to a temperature rise. Even so, the clearance between the angular ball bearings 2a and 2b is maintained.
[Selection] Figure 1

Description

  The present invention relates to a turbocharger bearing device that rotatably supports a rotating shaft of a turbocharger of an automobile.

The turbocharger of an automobile has a turbine attached to one end of the rotating shaft and an impeller attached to the other end, and an intermediate portion of the rotating shaft is inserted into a hole in the housing of the turbocharger. The rotating shaft is rotatably supported by the bearing device.
Conventionally, as such a turbocharger bearing device, a single row of angular ball bearings is arranged on both sides in the axial direction of the rotary shaft, and between them, the coil that elastically energizes the outer ring of both angular ball bearings on both sides in the axial direction. The thing provided with the spring and the spacer is known (for example, refer patent documents 1 and 2).

That is, in such a conventional turbocharger bearing device, a constant pressure preload is applied to the outer ring by the axial load of the coil spring in order to increase the rotational accuracy of the rotating shaft or prevent the balls from rotating and slipping. ing.
JP 11-101128 A Utility Model Registration No. 2577011

However, in a conventional turbocharger bearing device that applies a constant pressure preload to the outer ring, each ball rolls along the inner ring and outer ring raceways while the rotation axis is directed in a fixed direction. Only the same part around the equator corresponding to is in contact with the inner and outer ring tracks.
Therefore, when lubricating oil mixed with hard foreign matter is supplied to the bearing device in such a rolling state, the foreign matter bites into the rolling part of the ball and circulates around the outer equator of the ball. Wear marks may occur, and abnormal sounds may occur due to the wear marks.

  In view of such problems, the present invention can prevent the generation of abnormal noise by preventing band-shaped wear marks from being generated on the balls of an angular ball bearing even if the temperature rises. An object of the present invention is to provide a turbocharger bearing device.

  The present invention is a turbocharger bearing device that rotatably supports a rotating shaft of a turbocharger within a housing, the rotating shaft side inner ring having a pair of inner ring raceways separated in the axial direction of the rotating shaft, A pair of angular rings having a pair of outer rings on the housing side having an outer ring raceway facing the inner ring raceway, and a plurality of balls that are freely rollable between the inner ring raceway and the outer ring raceway in a state of zero or normal clearance. A ball bearing and a pressing member that presses the outer ring of one of the angular ball bearings toward the other angular ball bearing in the axial direction by thermally expanding at a high temperature. .

According to the present invention, the plurality of balls of the pair of angular ball bearings are movably interposed between the inner ring raceway and the outer ring raceway in a state of zero or a positive clearance, so that a constant pressure preload is applied to the outer ring. Unlike the case, the rotation axis of those balls is not constrained, and the rotation axis of the balls fluctuates with time.
For this reason, even if hard foreign matter is mixed in the lubricating oil supplied between the balls of the angular ball bearings and the inner ring and outer ring raceway, band-shaped wear marks are prevented from being generated on the outer peripheral surface of the balls as much as possible. It is possible to prevent or suppress the generation of abnormal noise associated with such wear marks.

  Further, according to the present invention, the pressing member thermally expands at a high temperature, thereby pressing the outer ring of one angular ball bearing toward the other angular ball bearing in the axial direction. Even if the rotating shaft and inner ring that have become expanded in the radial direction, the outer ring moves in the axial direction toward the side where the clearance between the inner ring and the inner ring widens.

  For this reason, even if the temperature of the rotating shaft rises due to the operation of the turbocharger, the clearance of the angular ball bearing is properly maintained, and band-shaped wear marks are formed on the outer peripheral surface of the ball not only at low temperatures but also at high temperatures. Can be prevented.

  As described above, according to the present invention, it is possible to prevent the occurrence of band-shaped wear marks on the outer peripheral surface of the ball not only at a low temperature but also at a high temperature, thereby preventing or suppressing the generation of abnormal noise. can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a bearing device 1 for a turbocharger according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of a turbocharger T in which the turbocharger bearing device 1 is incorporated.
As shown in FIG. 2, the turbocharger T of the present embodiment rotates a turbine 33 fixed to one end side (the right side in FIG. 2) of the rotating shaft 32 by the exhaust gas flowing through the exhaust passage 31. Yes.

The rotation of the rotating shaft 32 is transmitted to the impeller 34 fixed to the other end side (left side in FIG. 2) of the rotating shaft 32, and the impeller 34 rotates in the air supply passage 35.
As a result, the air sucked from the upstream opening of the air supply passage 35 is compressed, and the compressed air together with fuel such as gasoline and light oil is sent into a cylinder chamber of an engine (not shown).

The rotating shaft 32 of the turbocharger T rotates at a high speed of tens of thousands to tens of thousands (times / minute), and the rotation speed frequently changes according to the operating state of the engine. Therefore, the rotating shaft 32 is supported with respect to the housing 36 with a small rotational resistance by the turbocharger bearing device 1 provided in the housing 36 in order to reduce the rotation loss.
The turbocharger bearing device 1 includes a cylindrical bearing support portion 8 provided in a housing 36 of the turbocharger T, and is incorporated inside the cylinder. A rotating shaft 32 having a turbine 33 attached to one end and an impeller 34 attached to the other end is rotatably supported by the bearing device 1 at an intermediate portion thereof.

As shown in FIG. 1, the turbocharger bearing device 1 includes a pair of bearing support portions 8 and a pair of axially separated rotary shafts 32 that are coaxially inserted through the bearing support portions 8. Ball bearings 2a and 2b (first ball bearing 2a and second ball bearing 2b) and a cylindrical inner ring spacer 7 interposed between the ball bearings 2a and 2b are provided.
The first and second ball bearings 2a and 2b incorporated in the bearing support portion 8 in the housing 36 are both angular ball bearings, and the basic configurations of both are the same.

The first ball bearing 2a is disposed on the turbine 33 side (right side in FIG. 1) of the rotating shaft 32, and the second ball bearing 2b is disposed on the impeller 34 side (left side in FIG. 1) of the rotating shaft 32. Yes. Both ball bearings 2a, 2b are respectively connected between inner rings 3, 3 having an inner ring raceway 3a on the outer periphery, outer rings 4, 4 having an outer ring raceway 4a on the inner periphery, and between the inner ring raceway 3a and the outer ring raceway 4a. And a plurality of balls 5 that are movably arranged.
The inner ring 3 is formed in an annular shape, and the inner ring raceway 3a formed on the outer periphery thereof is an angular type raceway having a predetermined radius of curvature, and its axis is directed obliquely inward.

The outer ring 4 is also formed in an annular shape, and an angular outer ring raceway 4a having a predetermined radius of curvature is formed on the inner periphery of the outer ring 4 so as to face the inner ring raceway 3a. And in the angular ball bearings 2a and 2b of this embodiment, the inner ring 3 and the outer ring 4 have a cross-sectional shape having a so-called counterbore without a shoulder on one side.
The balls 5 as rolling elements are each held in a plurality of pockets 6a provided in an annular retainer 6 so as to be able to roll one by one, and by this retainer 6, the inner ring raceway 3a and the outer ring raceway 4a. Are arranged at predetermined intervals along the circumferential direction in an annular space formed between the two.

In the bearing device 1 of the present embodiment, no constant pressure preload is applied to each of the ball bearings 2a and 2b, and the plurality of balls 5 is in a state where there is zero clearance between the inner ring raceway 3a and the outer ring raceway 4a, or , Are interposed in a state where a predetermined appropriate positive clearance is obtained.
For example, when the shaft diameter of the rotary shaft 32 is 6 mm (φ6), the appropriate positive clearance is about 5 μm up to the radial clearance, about 5 μm up to the axial clearance, and at most 15 μm or less up to the radial clearance, up to the axial clearance. The member dimensions of the inner ring 3 and the outer ring 4 are set so as to be 50 μm or less.

At both ends in the axial direction of the bearing support portion 8, annular first storage portions 8 a and second storage portions 8 b are formed by thinning the both ends and widening the inner diameter.
Among these, the outer ring 4 of the first ball bearing 2 a is accommodated in the first accommodating part 8 a on the turbine 33 side, and the outer ring 4 is arranged so that axial displacement with respect to the bearing support part 8 is allowed. It is relatively loosely fitted into the inner peripheral surface of the storage portion 8a.
On the other hand, the second storage portion 8b has an axial depth substantially equal to the cross-sectional width of the outer ring 4, and the outer ring 4 has the end surface in contact with the step surface of the second storage portion 8b. It is stored in the second storage portion 8b.

On the other hand, the inner rings 3 and 3 of the ball bearings 2a and 2b are externally fitted and fixed to the intermediate portion of the rotating shaft 32 in a state in which axial displacement with respect to the rotating shaft 32 is also restricted. An axially intermediate portion of the shaft 32 is rotatably supported on the bearing support portion 8 of the housing 36 by a pair of ball bearings 2a and 2b separated in the axial direction.
The inner ring spacer 7 is externally fitted to the outer peripheral surface of the rotary shaft 32, and the axial distance between the inner rings 3 and 3 is maintained by bringing the inner rings 3 and 3 into contact with both end edges in the axial direction. is doing.

A mounting ring 9 is fixed to the end surface of the bearing support 8 on the turbine 33 side. The mounting ring 9 includes therein a storage groove 9a that opens to the outer ring 4 side of the bearing 2a, and the storage groove 9a is filled with a ring-shaped pressing member 10.
The pressing member 10 is in contact with the axially outer end surface of the outer ring 4 of the first ball bearing 2a, and is thermally expanded at a high temperature toward the second ball bearing 2b (in the direction of arrow b in FIG. 1). The outer ring 4 is pressed in the axial direction.

In addition, as a constituent material of the said pressing member 10, solid materials, such as a resin material with a larger linear expansion coefficient than the rotating shaft 32, can be employ | adopted, More specifically, the constituent material of the rotating shaft 32 is alloy steel. In the case of (SUJ2 or M50 etc.), for example, aluminum can be adopted.
The first storage portion 8a stores a positioning member 11 made of a coil spring whose one end is in contact with the stepped surface of the first storage portion 8a and whose other end is in contact with the outer ring 4.

This positioning member 11 does not give a constant pressure preload to the first ball bearing 2a, but elastically presses the outer ring 4 outwardly in the axial direction of the bearing support portion 8 to such an extent that a zero clearance or an appropriate positive clearance can be secured. Have power.
In addition, as this positioning member 11, not only the coil spring of illustration but a wave washer can also be comprised.

As shown in FIG. 2, an oil supply passage 37 is provided in the housing 36 in which the bearing support portion 8 is housed, and the ball bearings 2 a and 2 b are lubricated with the lubricating oil passing through the oil supply passage 37. Yes.
More specifically, the lubricating oil is fed from the upstream side of the oil supply passage 37 into the annular concave groove 12 (see FIG. 1) formed on the outer peripheral surface of the bearing support portion 8 when the engine equipped with the turbocharger T is operated. It is like that.

  Then, by filling the annular concave groove 12 with lubricating oil, an oil film (oil film) is formed over the entire circumference between the outer peripheral side of the bearing support portion 8 and the inner peripheral surface of the housing 36. The vibration is hardly transmitted to the housing 36. Thus, the oil film damper which attenuates the vibration based on rotation of the rotating shaft 32 is formed by the lubricating oil filled in the annular groove 12.

A part of the lubricating oil fed into the annular groove 12 is supplied from the supply hole 13 that penetrates the bearing support portion 8 in the radial direction toward the portion between the ball bearings 2a and 2b on the rotary shaft 32.
The lubricating oil supplied to the inside of the bearing support portion 8 enters between the inner ring 3 and the outer ring 4 of the ball bearings 2a and 2b to lubricate the rolling portions of the balls 5, and after this lubrication is finished. It is discharged from the oil discharge port 39.

  According to the turbocharger bearing device 1 having the above-described configuration, the plurality of balls 5 of the pair of angular ball bearings 2a and 2b are interposed between the inner ring raceway 3a and the outer ring raceway 4a in a state of zero or normal clearance. Therefore, unlike the case where constant pressure preload is applied to the outer ring 4, the rotation axes of the balls 5 are not constrained, and the rotation axes of the balls 5 vary with time.

  As a result, even if hard foreign matter is mixed in the lubricating oil supplied between the balls 5 of the angular ball bearings 2a and 2b and the inner ring and outer ring raceways 3a and 4a, band-shaped wear marks are formed on the outer peripheral surface of the balls 5. Can be prevented as much as possible, and the generation of abnormal noise associated with such wear marks can be prevented or suppressed.

  According to the turbocharger bearing device 1 of the present embodiment, the pressing member 10 attached to the end surface of the bearing support 8 on the turbine 33 side thermally expands at a high temperature, whereby the outer ring of one ball bearing 2a. 4 is pressed toward the other ball bearing 2b side in the axial direction, so that the rotating shaft 32 and the inner ring 3 that have become hot with high-speed rotation expand in the radial direction, for example, as indicated by an arrow a in FIG. Even so, the outer ring 4 of the first ball bearing 2a moves in the axial direction toward the side where the clearance with the inner ring 3 is widened (the arrow b side in FIG. 1).

  For this reason, even when the temperature of the rotary shaft 32 rises due to the operation of the turbocharger T, the clearance of the angular ball bearing 2a is properly maintained, and the band is formed on the outer peripheral surface of the ball 5 not only at a low temperature but also at a high temperature. It is possible to prevent the occurrence of the wear scar.

In addition, this invention is not limited to the said embodiment.
For example, in the above embodiment, in the turbocharger T, since the thermal expansion on the turbine 33 side is particularly severe, the pressing member 10 is attached on the turbine 33 side of the bearing support portion 8, but on the impeller 34 side of the bearing support portion 8. The pressing member 10 may be provided.

Further, in the above embodiment, the inner rings 3, 3 of the ball bearings 2a, 2b are separated in the axial direction, and the inner ring spacer 7 is interposed therebetween. However, the inner rings 3, 3 and the inner rings An inner ring cylinder having the spacer 7 integrally may be employed.
Furthermore, as a type of the cage 6, not only a hollow type as shown in FIG. 1 but also a wave type, for example, can be adopted.

It is sectional drawing which shows one Embodiment of the bearing apparatus for turbochargers. It is sectional drawing which shows schematic structure of the turbocharger which has the said bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing device for turbochargers 2a First ball bearing 2b Second ball bearing 3 Inner ring 3a Inner ring raceway 4 Outer ring 4a Outer ring raceway 5 Ball 6 Cage 7 Inner ring spacer 8 Bearing support portion 9 Mounting ring 10 Pressing member 11 Positioning member 32 Rotating shaft 33 Turbine 34 Impeller 36 Housing T Turbocharger

Claims (1)

A turbocharger bearing device for rotatably supporting a rotating shaft of a turbocharger in a housing,
Between the inner ring on the rotary shaft side having a pair of inner ring raceways separated in the axial direction of the rotary shaft, the pair of outer rings on the housing side having an outer ring raceway facing the inner ring raceway, and between the inner ring raceway and the outer ring raceway A pair of angular contact ball bearings having a plurality of balls that are freely rollable in a state of zero or a positive clearance between
A pressing member that presses the outer ring of one angular ball bearing toward the other angular ball bearing in the axial direction by thermally expanding at a high temperature;
A turbocharger bearing device comprising:

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