JP2002213248A - Turbocharger bearing device - Google Patents

Abstract

(57) [Problem] To provide a turbocharger bearing device for reducing vibration and noise due to self-excited vibration of a rotating shaft. The bearing device includes a floating bush bearing for supporting a rotary shaft of a turbocharger.
The floating bush bearing 7 has an inner peripheral surface width Lj and an outer peripheral surface width Lf.
And a ratio of the outer peripheral surface width Lf / the inner peripheral surface width Lj ≦ 1 is provided. The ratio (Lf / L) of the magnitude (amplitude) of self-excited vibration generated when the floating bush bearing 7 is used as the bearing device and the inner peripheral surface width Lj and the outer peripheral surface width Lf of the floating bush bearing 7 used.
j) has been found to have a relationship that the magnitude of the self-excited vibration decreases as the ratio decreases, so that the above configuration does not greatly change the configuration of the bearing structure of the turbocharger. Vibration and noise due to self-excited vibration can be suppressed to a low level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bearing device for a turbocharger.

[0002]

2. Description of the Related Art Conventionally, as a bearing device for supporting a rotating shaft rotating at high speed and light load, it is necessary to prevent self-excited vibrations called oil whirl and oil whip (oil-whip) accompanying high speed rotation. For this reason, inclined pad bearings are used in general working machines, and floating bush bearings disclosed in, for example, Japanese Patent Application Laid-Open No. 56-138423 are used in small turbochargers for automobiles and the like.

FIG. 6 shows an example of a conventional turbocharger bearing structure using a floating bush bearing as a bearing device.
Here, the rotating shaft 73 is rotatably supported by a pair of floating bush bearings 72 disposed in a bearing supporting cylindrical hole (rotating shaft chamber) provided in the housing 71 of the turbocharger. An intermediate sleeve 74 is provided between the two floating bush bearings 72. Each floating bush bearing 72 is supplied with lubricating oil from an oil supply source (not shown) via an oil supply path 75 provided in the housing 71. As a result, the lubricating oil is pumped into a gap of several tens of μm formed between the floating bush bearing 72 and the rotating shaft 73 rotating at a high speed to form an oil film. Rotate while floating above. At this time, the supplied lubricating oil also forms an oil film in a gap between the housing 71 and the floating bush bearing 72. Therefore, the floating bush bearing 72 floats with respect to the housing 71 in the bearing support cylindrical hole provided in the housing 71, and the rotation shaft is rotated via an oil film between the floating bush bearing 72 and the rotation shaft 73. Affected by the rotation of the rotation shaft 73, the rotation speed of the rotation shaft 73 is 2
It rotates at a rotation speed of 0 to 50%.

As a result, the relative speed of the sliding surface between the floating bush bearing 72 and the rotary shaft 73 decreases, and whirling of the rotary shaft is damped by the damper effect of the oil film. Can be supported.

[0005]

However, in recent years,
2. Description of the Related Art Turbochargers for automobiles have been increasingly supercharged and operated at high speeds, and their rotation speed has reached 200,000 to 300,000 rpm. Along with this, it has become difficult to reduce the occurrence of self-excited vibration to a level at which there is no problem with conventional floating bush bearings, and in turbochargers for automobiles that require quietness, this self-excited vibration causes Noise is becoming a problem.

On the other hand, it is conceivable to apply a tilt pad bearing used in general industrial machines to a turbocharger. However, the tilt pad bearing has a complicated structure and cannot be made compact because a turbocharger cannot be used. However, there are problems that it is difficult to use it and that the price is high.

In view of the above problems, the present invention provides a turbocharger for reducing vibration and noise due to self-excited vibration of a rotating shaft without largely changing the configuration of a bearing structure using a floating bush bearing as a bearing device for a turbocharger. It is an object of the present invention to provide a bearing device.

[0008]

Means for Solving the Problems To solve the above problems, the means described in claim 1 can be adopted.

According to a first aspect of the present invention, a bearing device for a turbocharger comprises a floating bush bearing, and a ratio of an inner peripheral surface width Lj to an outer peripheral surface width Lf of the floating bush bearing is determined by an outer peripheral surface width Lf.
f / the inner peripheral surface width Lj ≦ 1.

This feature is characterized by the ratio (amplitude) of the magnitude (amplitude) of self-excited vibration generated when the floating bush bearing is used and the inner peripheral surface width Lj and the outer peripheral surface width Lf of the floating bush bearing used. This is based on the correlation found between the surface width Lf / the inner peripheral surface width Lj). That is, the ratio of the magnitude (amplitude) of the self-excited vibration generated when the floating bush bearing is used to the inner peripheral surface width Lj and the outer peripheral surface width Lf of the used floating bush bearing (outer peripheral surface width Lf / inner There is a correlation as shown in FIG. 3 between the inner peripheral surface width Lj and the outer peripheral surface width Lf (the outer peripheral surface width Lf).
It can be understood that the magnitude of self-excited vibration can be suppressed to a very small level by setting the / inner peripheral surface width Lj) to 1 or less.

Therefore, by adopting the configuration of the first aspect, the magnitude of self-excited vibration can be suppressed to a very small level, and the configuration of the bearing structure using the floating bush bearing as the bearing device of the turbocharger is greatly changed. Without doing so, it is possible to reduce vibration and noise due to self-excited vibration.

Further, in order to solve the same problem, a second aspect is provided.
May be adopted.

According to a second aspect of the present invention, there is provided a turbocharger bearing device comprising a floating bush bearing, and an inner diameter side clearance Cj and an outer diameter side clearance Cf of the floating bush bearing.
Is a ratio of outer diameter side clearance Cf / inner diameter side clearance Cj ≧ 2.

This feature is based on the ratio of the magnitude (amplitude) of the self-excited vibration generated when the floating bush bearing is used to the inner clearance Cj and the outer clearance Cf of the used floating bush bearing. This is based on the correlation found between the radial clearance Cf / the radial clearance Cj). That is, the ratio of the magnitude (amplitude) of the self-excited vibration generated when the floating bush bearing is used and the inner clearance Cj and the outer clearance Cf of the used floating bush bearing (outer clearance Cf / There is a correlation between the inner diameter clearance Cj and the inner diameter clearance Cj as shown in FIG. 5, and from this relation, the ratio of the inner diameter side clearance Cj to the outer diameter side clearance Cf of the floating bush bearing (outer diameter side clearance Cf / inner diameter). It can be seen that by setting the side clearance Cj) to 2 or more, the magnitude of the self-excited vibration can be suppressed to a very small level.

Therefore, by adopting the structure described in claim 2, the magnitude of self-excited vibration can be suppressed to a very small level, and the structure of a bearing structure using a floating bush bearing as a bearing device of a turbocharger is greatly changed. Without doing so, it is possible to reduce vibration and noise due to self-excited vibration.

Furthermore, in order to solve the same problem, the means described in claim 3 can be adopted.

According to a third aspect of the present invention, in the turbocharger bearing device according to the first or second aspect, the bearing device is a semi-floating bush bearing instead of a floating bush bearing.
It is composed of

The ratio of the magnitude (amplitude) of the self-excited vibration to the width of the inner peripheral surface and the outer peripheral surface of the bearing (outer peripheral surface width Lf / inner peripheral surface width L
j), and the correlation between the magnitude (amplitude) of the self-excited vibration and the ratio of the clearance between the inner diameter side and the outer diameter side of the bearing (outer diameter side clearance Cf / inner diameter side clearance Cj) is as follows:
Semi-floating bush bearing (semi-floating bearing)
Therefore, the same operation and effect as described above with respect to claim 1 or claim 2 can be obtained by adopting the configuration according to claim 3.

[0019]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a bearing structure of a turbocharger provided with the turbocharger bearing device of the present invention. Where 1 is the housing of the turbocharger,
Reference numeral 2 denotes a turbine chamber formed in the housing 1, and reference numeral 3 denotes a turbine wheel housed in the turbine chamber 2. or,
4 is a compressor chamber formed in the housing 1, 5 is a substantially cylindrical rotary shaft chamber formed in the housing 1 between the turbine chamber 2 and the compressor chamber 4, and 6 is housed in the rotary shaft chamber 5. Rotary shafts connecting the turbine wheel 3 and a compressor impeller (not shown) housed in the compressor chamber are shown.

A pair of floating bush bearings 7 are arranged in a rotary shaft chamber 5 formed in the housing 1 so as to be mounted around the outer peripheral surface of the rotary shaft 6 and are spaced apart in the direction of the rotary axis KK. The rotating shaft 6 is supported by these floating bush bearings 7 so as to be rotatable around the rotating axis KK. That is,
The floating bush bearing 7 is arranged between the rotating shaft 6 and the inner peripheral surface of the rotating shaft chamber 5 surrounding the rotating shaft 6 (that is, the inner peripheral surface of the housing 1). In the embodiment shown in FIG. 1, in order to prevent the movement of the floating bush bearing 7 in the direction of the rotation axis KK, a ring-shaped stop member 10 such as a circlip is rotated adjacent to the floating bush bearing 7. It is disposed in the shaft chamber 5 as shown in FIG. The movement of the floating bush bearing 7 in the direction of the rotation axis KK may be prevented by other known means such as disposing an intermediate sleeve between the two floating bush bearings 7.

The outer peripheral surface of the floating bush bearing 7 and the rotating shaft chamber 5
And a slight gap is formed between the inner peripheral surface of the floating bush bearing 7 and the outer peripheral surface of the rotating shaft 6. Each floating bush bearing 7 is provided with a plurality of holes 8 that penetrate the floating bush bearing 7 in the radial direction and are spaced apart in the circumferential direction.

Further, an oil supply passage 9 is provided in the housing 1.
The lubricating oil is supplied to each floating bush bearing 7 from an oil supply source (not shown) via the oil supply path 9.

With the above-described configuration, each floating bush bearing 7 can be relatively rotated with respect to both the housing 1 and the rotating shaft 6, and lubricating oil is supplied to each floating bush bearing 7. Then, the lubricating oil is supplied to both the inner peripheral surface and the outer peripheral surface of each floating bush bearing 7 through the through hole 8 or the like, and an oil film is formed on both surfaces.

The above structure is substantially the same as the turbocharger bearing structure known from the prior art. However, in the turbocharger bearing device of the first embodiment of the present invention, that is, the floating bush bearing 7, FIG. As shown, the width Lj of the inner peripheral surface of the floating bush bearing 7 (that is, the width of the surface that faces substantially parallel to the outer peripheral surface of the rotating shaft 6) and the width Lf of the outer peripheral surface of the floating bush bearing 7 (that is, the cylindrical shape) The ratio of the outer peripheral surface width Lf to the outer peripheral surface width Lf
/ Inner peripheral surface width Lj ≦ 1. In the embodiment shown in FIG. 2, the outer peripheral surface width Lf / the inner peripheral surface width Lj ≦ by making the chamfer width on the outer peripheral surface side of both ends of the floating bush bearing 7 larger than the chamfer width on the inner peripheral surface side.
1 is realized.

The inventors of the present invention conducted research on prevention of self-excited vibration of a rotating shaft supported by a floating bush bearing, and found that self-excited vibration generated when a floating bush bearing was used as a bearing device. The correlation between the size (amplitude) and the ratio of the inner peripheral surface width Lj to the outer peripheral surface width Lf of the used floating bush bearing (outer peripheral surface width Lf / inner peripheral surface width Lj) has a correlation as shown in FIG. I found something. That is, the magnitude of the generated self-excited vibration decreases as the ratio of the inner peripheral surface width Lj to the outer peripheral surface width Lf (outer peripheral surface width Lf / inner peripheral surface width Lj) of the floating bush bearing decreases. From the relationship shown in FIG. 3, the ratio of the inner peripheral surface width Lj to the outer peripheral surface width Lf of the floating bush bearing (outer peripheral surface width Lf / inner peripheral surface width Lf)
By setting j) to 1 or less, although self-excited vibration occurs, its magnitude can be suppressed to a very small level.

Accordingly, the configuration of the first embodiment of the present invention, that is, the ratio of the inner peripheral surface width Lj to the outer peripheral surface width Lf of the floating bush bearing is such that the outer peripheral surface width Lf / the inner peripheral surface width Lj ≦ 1. With such a configuration, vibration and noise due to self-excited vibration can be reduced without largely changing the configuration of a bearing structure using a floating bush bearing as a bearing device of a turbocharger.

In the embodiment shown in FIG. 2, as described above, the outer peripheral surface width Lf / mm is increased by making the chamfer width on the outer peripheral surface side of both ends of the floating bush bearing 7 larger than the chamfer width on the inner peripheral surface side. Although the configuration in which the inner peripheral surface width Lj ≦ 1 is realized, the configuration according to the present invention may be realized by another method.

On the other hand, in the bearing device of the turbocharger according to the second embodiment of the present invention, that is, the floating bush bearing 7, as shown in FIG. 4, the clearance Cj on the inner diameter side of the floating bush bearing 7 (ie, the floating bush bearing 7). Ratio between the inner diameter and the outer diameter of the rotary shaft 6) and the outer diameter side clearance Cf of the floating bush bearing 7 (that is, the difference between the inner diameter of the cylindrical rotary shaft chamber 5 and the outer diameter of the floating bush bearing 7). Are configured such that the outer diameter side clearance Cf / the inner diameter side clearance Cj ≧ 2.

The inventors of the present invention determined that the ratio of the magnitude of the self-excited vibration to the ratio of the inner peripheral surface width Lj to the outer peripheral surface width Lf of the floating bush bearing (outer peripheral surface width Lf / inner peripheral surface width Lj) was calculated. In addition to the correlation, the ratio between the magnitude (amplitude) of self-excited vibration generated when a floating bush bearing is used as the bearing device and the inner clearance Cj and the outer clearance Cf of the floating bush bearing used. (Outer diameter side clearance Cf / inner diameter side clearance Cj) as shown in FIG. That is, the magnitude of the generated self-excited vibration becomes smaller as the ratio of the inner clearance Cj to the outer clearance Cf (outer clearance Cf / inner clearance Cj) of the floating bush bearing increases. From the relationship shown in FIG. 5, self-excited vibration is generated by setting the ratio of the inner clearance Cj to the outer clearance Cf (outer clearance Cf / inner clearance Cj) of the floating bush bearing to 2 or more. However, it can be seen that the size can be suppressed to a very small level.

Therefore, the configuration of the second embodiment of the present invention, that is, the ratio of the inner diameter side clearance Cj to the outer diameter side clearance Cf of the floating bush bearing is such that the outer diameter side clearance Cf / the inner diameter side clearance Cj ≧ 2. With such a configuration, vibration and noise due to self-excited vibration can be reduced without largely changing the configuration of a bearing structure using a floating bush bearing as a bearing device of a turbocharger.

The magnitude (amplitude) of the self-excited vibration and the ratio of the width of the inner peripheral surface to the outer peripheral surface of the bearing (outer peripheral surface width Lf / inner peripheral surface width Lj) shown in FIGS. The correlation and the correlation between the magnitude (amplitude) of the self-excited vibration and the ratio of the clearance between the inner diameter side and the outer diameter side of the bearing (the outer diameter side clearance Cf / the inner diameter side clearance Cj) are determined by preventing rotation. Since it has been confirmed that this is also true in a semi-floating bush bearing (semi-floating bearing), in which it is impossible to rotate itself but it is possible to move within the clearance, In the embodiment, the same effect can be obtained even when the floating bush bearing 7 is a semi-floating bush bearing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a bearing structure of a turbocharger provided with a bearing device for a turbocharger according to the present invention.

FIG. 2 is an enlarged sectional view showing a floating bush bearing which is a bearing device of the turbocharger according to the first embodiment of the present invention.

FIG. 3 shows a ratio (outer circumference) of a magnitude (amplitude) of self-excited vibration generated when a floating bush bearing is used as a bearing device and an inner peripheral surface width Lj and an outer peripheral surface width Lf of the floating bush bearing used. It is a figure which shows the relationship with surface width Lf / inner peripheral surface width Lj).

FIG. 4 is an enlarged sectional view showing a floating bush bearing which is a bearing device of a turbocharger according to a second embodiment of the present invention.

FIG. 5 shows the ratio (outside) between the magnitude (amplitude) of self-excited vibration generated when a floating bush bearing is used as a bearing device and the inner clearance Cj and the outer clearance Cf of the used floating bush bearing. It is a figure which shows the relationship of radial side clearance Cf / radial side clearance Cj).

FIG. 6 is a sectional view showing a bearing structure of a conventional turbocharger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Turbine room 3 ... Turbine wheel 4 ... Compressor room 5 ... Rotating shaft room 6 ... Rotating shaft 7 ... Floating bush bearing 8 ... Through-hole 9 ... Oil supply path 10 ... Stop member

Continued on front page (72) Inventor Takanori Fukuda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G005 EA04 EA16 FA11 FA12 FA41 GB56 3J011 AA20 BA02 KA01 NA00 RA03

Claims (3)

[Claims] 1. A bearing device provided between a rotating shaft connecting a compressor impeller of a turbocharger and a turbine wheel and an inner peripheral surface of a housing of a turbocharger surrounding the rotating shaft, wherein the bearing device is A bearing device for a turbocharger, comprising a floating bush bearing, wherein a ratio of an inner peripheral surface width to an outer peripheral surface width of the floating bush bearing is outer peripheral surface width / inner peripheral surface width ≦ 1. 2. A bearing device provided between a rotating shaft connecting a compressor impeller of a turbocharger and a turbine wheel, and an inner peripheral surface of a housing of the turbocharger surrounding the rotating shaft, wherein the bearing device is A bearing device for a turbocharger, comprising a floating bush bearing, wherein a ratio of an inner diameter side clearance and an outer diameter side clearance of the floating bush bearing is outer diameter side clearance / inner diameter side clearance ≧ 2. 3. The turbocharger bearing device according to claim 1, wherein a semi-floating bush bearing (semi-floating bearing) is used instead of the floating bush bearing.