JPH09236118A - Floating bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly arrange an oil groove in the inner surface of a cylinder and set the size thereof to a proper value. SOLUTION: A floating bearing consists a cylinder 2 having an inner surface fitted in a rotary shaft 1 and an outer surface fitted in a bearing bush 3 and a feed oil port 5 is radially formed in the inner surface of the bearing bush 3 and a feed oil socket 4 radially extending through in a position corresponding to the feed oil port 5 is formed in the cylinder 2. A lateral groove 6 axially extending from the feed oil socket 4 is formed in the inner surface of the cylinder 2, and a vertical groove 7 is peripherally formed from the feed oil socket 4. In which case, provided L is the length of a cylinder, L1 is the width of the vertical groove, D1 is the depth of the vertical groove, D2 is the depth of a lateral groove, C1 is a gap on one side between the outer peripheral surface of a shaft and the inner surface of a cylinder, and C2 is a gap on one side between the inner surface of a bearing bush and the outer surface of a cylinder, width L1 of the vertical groove and depth D1 of the vertical groove is D1 are set within a range of a formula 1 of 0.1L<=L1<=0.3L and a formula 2 of (D2+ C1+C2)<=D1<=(C1+C21).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a floating bearing used as a bearing of a rotary machine.

[0002]

2. Description of the Related Art A supercharger rotates a turbine with an exhaust gas from an internal combustion engine such as a diesel engine to rotate a compressor to generate compressed air and supply the compressed air to the internal combustion engine. This supercharger operates at a high rotational speed, and a floating bearing is used as a radial bearing. The inner surface of the floating bearing is fitted to the rotary shaft of the turbocharger, the outer surface is fitted to the bearing bush, and the load from the shaft is transmitted to the bearing bush by the oil film of the lubricating oil injected into each fitting surface.

FIG. 8 is a sectional view of an example of a conventional floating bearing. The rotary shaft 1 is fitted to the inner surface of the cylinder 2 that constitutes the floating bearing,
The outer surface is fitted with the inner surface of the bearing bush 3. The bearing bush 3 is provided with an oil supply port 5, and the cylinder 2 is provided with an oil supply port 4 at a position corresponding thereto. Since the bearing bush 3 is fixed and the cylinder 2 rotates, lubricating oil is injected into the cylinder 2 when the oil supply port 4 comes to the position of the oil supply port 5.
On the other hand, lubricating oil is constantly supplied to the outer surface of the cylinder 2 from the oil supply port 5.

[0004]

When the rotary shaft 1 rotates as indicated by the arrow, the lubricating oil flowing from the oil supply port 4 flows as indicated by F1 and a part thereof as indicated by F2. However, it is difficult for the lubricating oil to rotate in the range indicated by P. It is difficult for the lubricating oil to rotate around the rotating shaft 1 because centrifugal force acts on the lubricating oil. For this reason, grooves are provided in the inner surface of the cylinder in the axial direction and the circumferential direction so that the lubricating oil is evenly distributed on the inner surface of the cylinder, but this is not sufficient. When the distribution of the oil film becomes non-uniform and there is a portion where the oil film is insufficient, the whirl shaft vibration becomes large. The whirl shaft vibration is a low-cycle vibration in which the frequency does not change much even if the rotation speed of the shaft changes as shown in A of FIG. . When the vibration of the whirl shaft becomes large, the rotating shaft 1 and the inner surface of the cylinder 2 come into contact with each other to cause metal wear and seizure, which causes a problem that the life of the rotating shaft 1 and the cylinder 2 becomes short.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a floating bearing in which whirl shaft vibration is reduced by appropriately arranging and dimensioning the oil grooves on the inner surface of the cylinder. To aim.

[0006]

In order to achieve the above object, the invention of claim 1 comprises a cylinder having an inner surface fitted with a shaft and an outer surface fitted with a bearing bush, and the bearing bush inner surface is lubricated in a radial direction. There is a port, the cylinder is provided with a refueling port penetrating in a radial direction at a position corresponding to the refueling port, a lateral groove is provided on the inner surface of the cylinder in the axial direction from the refueling port, and the refueling port is further provided. A longitudinal groove is provided in the circumferential direction from the mouth, where L is the length of the cylinder, L1 is the width of the longitudinal groove, D1 is the depth of the longitudinal groove, D2 is the depth of the lateral groove, and C1 is one side of the outer surface of the shaft and the inner surface of the cylinder. Gap, C2
Is a one-side gap between the inner surface of the bearing bush and the outer surface of the cylinder: 0.1L ≦ L1 ≦ 0.3L (1) (D2 + C1 + C2) ≦ D1 ≦ 10 (C1 + C2) (2) The width L1 of the vertical groove and the vertical groove The depth D1 is defined by the above equations (1) and (2).

The lateral grooves provided on the inner surface of the cylinder are related to the oil distribution in the axial direction of the inner surface of the cylinder, and the vertical grooves are related to the oil distribution in the circumferential distribution. In order to make the flutes work effectively and to make the distribution in the circumferential direction appropriate and to reduce the whirl shaft vibration, the flute width L1 is set to the range of the formula (1), and the depth D1 of the vertical axis is set to (2). It was experimentally found that the range of the formula) should be set.
It should be noted that C1 and C2 represent a gap on one side, which is a half of the gap on both sides.

According to the second aspect of the invention, the bearing bush has one oil supply port, and the cylindrical oil supply ports are provided on the vertical groove at three equal intervals. With such an arrangement, an appropriate oil film is obtained, and the whirl shaft vibration is reduced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of a supercharger including a floating bearing of the present invention. The rotary shaft 1 has a compressor blade C at one end and a turbine blade T at the other end. The bearing housing 12 supports the rotating shaft 1 and is connected to the compressor housing 14 via the support ring 13 on the compressor blade C side and is connected to the turbine housing 15 on the turbine blade T side to form a supercharger. The supercharger is attached to the engine 16 by the attachment legs 13a of the support ring 13.

The bearing housing 12 supports the rotary shaft 1 by a journal bearing 17 and a thrust bearing 18.
Further, an oil supply passage 19 and an oil discharge passage 20 are provided inside, and oil is supplied from the oil supply passage 19 to both bearings 17 and 18 to allow the bearings 17 and 18 to freely fall into the oil discharge passage 20. The journal bearing 17 is composed of a cylinder 2 that constitutes a floating bearing and a bearing bush 3 that axially supports the cylinder 2. The bearing bush 3 is provided with an oil supply port 5 and supplies oil from an oil supply passage 19 to the cylinder 2. .

FIG. 2 is a vertical sectional view of a cylinder 2 which constitutes a floating bearing, and FIG. 3 is a sectional view taken along line XX of FIG. Refueling receiving ports 4 are provided at equal intervals (120 ° intervals) on the central circumference of the length L of the cylinder 2, and each of the refueling receiving ports 4 is provided with lateral grooves 6 to both ends in the axial direction. A vertical groove 7 is provided by connecting three refueling ports 4 in the circumferential direction.

FIG. 4 is a view showing the relationship between the rotary shaft 1, the cylinder 2 and the bearing bush 3. The cylinder 2 has its refueling port 4
Are arranged so as to coincide with the oil supply port 5 of the bearing bush 3. L1 indicates the width of the vertical groove 7, and D1 indicates the depth of the vertical groove. Note that D2 indicates the depth of the lateral groove 6 as shown in FIG. The width of the lateral groove 6 is not particularly specified because it has little relation to the size of the vertical groove 7 regarding the distribution of oil in the circumferential direction, but is set to a value corresponding to the diameter of the oil supply port 4. C1 is a one-side gap between the outer surface of the rotating shaft 1 and the inner surface of the cylinder 2, and C2 is the inner surface of the bearing bush 3 and the cylinder 2.
Is a gap on one side from the outer surface of C2, C1 is 1/2 the difference between the inner diameter of the cylinder 2 and the outer diameter of the rotary shaft 1, and C2 is the bearing bush 3
1/2 the difference between the inner diameter of the cylinder and the outer diameter of the cylinder 2.

Next, the experimental result of the shaft vibration will be described.
In the experiment, a plurality of cylinders in which the dimensions of the vertical groove of the cylinder 2 are systematically changed are manufactured, the rotation speed of the supercharger is changed, and the cycle and amplitude of the generated shaft vibration are measured. The shape of the cylinder 2 is the shape shown in FIGS. FIG. 5 shows the case where the vertical groove 7 is not provided and the following dimensions are obtained. D1 = 0 (without vertical groove) D2 = 3.9 (C1 + C2)

In FIG. 5, the horizontal axis represents the number of revolutions per minute (RPM), the vertical axis represents the cycle of vibration (Hz), and the size of the circle represents the amplitude. The same applies to FIGS. The design rotation speed of the supercharger is about 40,000 rotations, but the experiment was performed up to 50,000 rotations. A indicates whirl shaft vibration, and B indicates primary shaft vibration. The whirl shaft vibration A is a low-cycle vibration and its cycle increases in proportion to the rotation speed, but the rate of increase is extremely small.

FIG. 6 shows a case where a shallow vertical groove is provided and has the following dimensions. D1 = 2.7 (C1 + C2) = 0.54 (D2 + C1 + C2) L1 = 0.2L

In the case of FIG. 6, the whirl axis vibration A is almost the same as in the case of FIG. 5, and it is shown that the shallow vertical groove has no effect. However, the amplitude of the primary vibration is decreasing.

FIG. 7 shows the case where proper vertical grooves are provided, and the following dimensions are confirmed. D1 = 8 (C1 + C2) = 1.6 (D2 + C1 + C2) L1 = 0.2L

In the case of FIG. 7, the whirl shaft vibration is greatly reduced, and the cycle is constant regardless of the rotation speed. 250
The vibration does not occur up to 00 rotations, and a small vibration occurs up to 45000 rotations, which is a state in which it practically hardly occurs. The amplitude of the primary vibration is smaller than that in Fig. 5.

By arranging the results of such an experiment, as shown in FIG. 7, the depth of the vertical groove should be made practically in such a state that almost no vibration of the whirl shaft occurs and the design condition as the bearing is taken into consideration. The D1 and the width L1 are defined by the following equations (1) and (2). 0.1L ≦ L1 ≦ 0.3L (1) (D2 + C1 + C2) ≦ D1 ≦ 10 (C1 + C2) (2) where L is the cylinder length, L1 is the vertical groove width, and D1 is the vertical groove depth. , D2 is the depth of the lateral groove, C1 is a one-side gap between the shaft outer surface and the cylinder inner surface, and C2 is a one-side gap between the bearing bush inner surface and the cylinder outer surface.

[0020]

As is apparent from the above description, according to the present invention, the dimensions of the vertical groove on the inner surface of the cylinder forming the floating bearing are represented by the equations (1) and (2). Vibration can be greatly reduced. This reduction also extends the life of the shaft and its bearings.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a supercharger using a floating bearing of the present invention.

FIG. 2 is a vertical cross-sectional view of a cylinder that constitutes the floating bearing of the present embodiment.

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is a diagram showing a relationship between a rotary shaft, a cylinder, and a bearing bush.

FIG. 5 is a diagram showing experimental results showing the case where there is no vertical groove.

FIG. 6 is a diagram showing experimental results showing a case where a vertical groove is shallow.

FIG. 7 is a diagram showing experimental results, showing a case where the vertical groove has an appropriate dimension.

FIG. 8 is a diagram showing an example of a conventional floating bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 2 cylinder 3 bearing bush 4 oil supply port 5 oil supply port 6 lateral groove 7 vertical groove 12 bearing housing 14 compressor housing 15 turbine housing 17 journal bearing 18 thrust bearing 19 oil supply passage 20 oil drainage passage

Claims (2)

[Claims] 1. A cylinder having an inner surface fitted with a shaft and an outer surface fitted with a bearing bush, and an inner surface of the bearing bush has a lubrication port in a radial direction, and the cylinder has a position corresponding to the lubrication port. A refueling port penetrating in the radial direction is provided, a lateral groove is provided on the inner surface of the cylinder in the axial direction from the refueling port, and a vertical groove is provided in the circumferential direction from the refueling port, and L is the length of the cylinder. , L1 is the width of the vertical groove, D1 is the depth of the vertical groove, D2 is the depth of the horizontal groove, C1 is the one-side gap between the shaft outer surface and the cylinder inner surface, and C2 is the one-side gap between the bearing bush inner surface and the cylinder outer surface. 0.1L ≦ L1 ≦ 0.3L (1) (D2 + C1 + C2) ≦ D1 ≦ 10 (C1 + C2) (2) The width L1 of the flute and the depth D1 of the flute are the above formula (1) and (2). Floating bearing characterized by being expressed by a formula. 2. The floating bearing according to claim 1, wherein the bearing bush has one oil supply port, and three cylindrical oil supply ports are provided on the vertical groove at equal intervals.