JPH0536995Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a floating bearing used, for example, in a turbocharger of an internal combustion engine.

[Conventional technology]

Turbochargers in internal combustion engines use floating bearings to support the turbine shaft. Such floating bearings are described in, for example, Japanese Unexamined Utility Model Publications No. 56-143316 and Japanese Utility Model Application No. 61-86535.

As shown in FIG. 4, the cylindrical floating bearing 10 is installed between the inner circumferential wall surface of a cylindrical mounting hole formed in the housing 12 and the outer circumferential surface of the rotating shaft 16 at predetermined positions for both. The rotating shaft 16 is inserted while leaving a clearance of the size of , and supports the rotating shaft 16 while floating in the lubricating oil supplied to each clearance.

[The problem that the idea attempts to solve]

Such a floating bearing 10 is
While the rotational speed of the rotating shaft 16 is low, it is in a depressed position at the bottom of the mounting hole of the housing 12 due to its own weight, but as the rotational speed increases, the rotation of the lubricating oil flowing in the rotational direction of the rotating shaft 16 between the two clearances. It floats and rotates on the motion (only the flow of lubricating oil between the floating bearing 10 and the rotating shaft 16 is shown by arrows in FIG. 4). The center of this floating rotation does not necessarily coincide with the center of the mounting hole of the housing 12, and the distribution of lubricating oil around the rotating shaft 16 may become uneven, resulting in eccentric lubrication. There was a problem in that the rotating shaft 16 whirled around under the influence of the rotational movement of the oil.

[Means to solve the problem]

In order to solve this problem, the present invention is a hollow body whose outer peripheral surface is cylindrical, and whose inner peripheral surface faces the surface of the rotating shaft with a clearance left behind.
A lubricating oil supply hole is formed at each end in the axial direction to form a conical surface, and extends radially between the inner circumferential surface and the outer circumferential surface. To provide a floating bearing characterized in that axial lubricating oil relief grooves formed to reach a conical surface are arranged apart from each other in the circumferential direction so that they do not directly intersect with each other. .

[Effect]

The lubricating oil supplied to the clearance between the rotating shaft and the inner peripheral surface of the floating bearing through the radial lubricating oil supply hole spreads in the circumferential direction as the rotating shaft rotates, forming an oil film. However, if the thickness of the oil film is uniform over the entire circumference, the center of the floating bearing and the rotating shaft will be aligned, and a good shaft support condition will be obtained. However, depending on the conditions, the distribution of lubricating oil may not be uniform in the circumferential direction or the axial direction, which may cause the rotating shaft to become eccentric, causing whirling or vibration.

In this invention, when the distribution of lubricating oil is uneven in the circumferential direction and there is a part where the pressure within the oil film is high, excess lubricating oil in that part is formed on the inner peripheral surface of the floating bearing. Since the lubricating oil escapes toward the conical surfaces on both ends through the axial direction of the lubricating oil relief groove, there are no parts where the pressure inside the oil film is too high. In addition, since the lubricating oil flows in the axial direction through the lubricating oil relief groove, the distribution of the lubricating oil in the axial direction becomes even, and the thickness of the oil film is constant everywhere in the circumferential and axial directions. , good shaft support can be obtained. Moreover, since the radial lubricating oil supply hole and the axial lubricating oil relief groove do not directly intersect on the inner circumferential surface of the floating bearing, the lubricating oil supplied from the lubricating oil supply hole immediately lubricates the floating bearing. This prevents the oil from escaping into the relief groove and forming an oil film, and the lubricant supplied from the lubricant supply hole once spreads over the inner peripheral surface of the floating bearing to form an oil film and support the bearing load. After securing the oil pressure, the lubricating oil escapes to the relief groove, so the supplied lubricating oil is not wasted.

〔Example〕

Referring to FIGS. 1 and 2, the floating bearing 10 is formed in a hollow cylindrical shape, and is, for example, a housing 1 of a turbocharger of an internal combustion engine.
It is arranged in the mounting hole 14 provided in 2. This floating bearing 10 is used as a radial bearing that supports the rotating shaft 16. In this case, the rotating shaft 16 is a turbine shaft of a turbocharger.

The floating bearing 10 has a predetermined clearance between its outer circumferential surface and the inner circumferential surface of the mounting hole 14 provided in the housing 12, and a predetermined clearance between the inner circumferential surface and the outer circumferential surface of the rotating shaft 16. A predetermined clearance is also provided. Thereby, lubricating oil is supplied to the outer clearance space and the inner clearance space of the floating bearing 10. For this purpose, the housing 12 is formed with a lubricating oil supply passage 18 leading to the mounting hole 14, and further includes:
A plurality of lubricating oil supply holes 20 are formed in the floating bearing 10 at positions on the center cross section and penetrating the inner and outer circumferential surfaces in the radial direction.

Furthermore, an axial lubricating oil relief groove 22 is provided on the inner circumferential surface of the floating bearing 10.
A plurality of axial lubricating oil relief grooves 22 are provided at regular intervals in the circumferential direction, and it can be seen in FIG. 1 that the lubricating oil relief grooves 22 and the lubricating oil supply holes 20 are formed alternately. Furthermore, the inner peripheral surface of the floating bearing 10 has three regions when viewed in the axial direction. a central region is formed by a cylindrical surface;
The regions on both sides thereof are formed into a tapered shape that widens outward from the cylindrical surface. The depth of the lubricating oil relief groove 22 is smaller than the radial distance between this cylindrical surface and the outer maximum diameter of the taper.
Furthermore, as shown in FIG. 2, since the width of the opening to the inner peripheral surface of the lubricating oil relief groove 22 is relatively small, the surface area of the lubricating oil relief groove 22 on the inner peripheral surface of the floating bearing 10 is limited. The surface area of the floating bearing 10 excluding the lubricating oil relief groove 22 can sufficiently form a bearing surface.

Referring to FIG. 3, in the present invention, an axial lubricating oil relief groove 22 is provided on the inner peripheral surface of the floating bearing 10, so that the lubricating oil escapes from the bearing surface in the axial direction as shown by the arrow. , thereby acting to adjust the uneven distribution of lubricating oil. That is, in FIG. 3, the clearance between the rotating shaft 16 and the floating bearing 10 is large in the upper half and small in the lower half, but as the rotating shaft 16 rotates, the floating bearing 10 is dragged by the lubricating oil and rotates half a turn. Then, the lower half of the clearance becomes larger and the rotating shaft is lifted upward by the pressure, but at this time, the lubricating oil under excessive pressure escapes in the axial direction from the axial lubricating oil relief groove 22. The lifting amount of the rotating shaft 16 is reduced, and the eccentric movement of the rotating shaft 16 is alleviated. Note that if you try to obtain the same effect without providing the axial lubricant relief groove 22, the floating bearing 10
It is necessary to increase the clearance between the rotary shaft 16 and the rotary shaft 16. Therefore, in the present invention, such a bearing clearance can be reduced compared to the conventional structure, and the runout of parts attached to the rotating shaft 16, such as a turbine wheel or a compressed impeller, can be reduced. Become.

[Effect of idea]

On the inner peripheral surface of the floating bearing,
The lubricating oil relief grooves formed in the axial direction to reach the conical surfaces at both ends are spaced apart in the circumferential direction so that they do not directly intersect with the lubricating oil supply holes, so that the lubricating oil is This prevents the lubricant from immediately escaping into the lubricant relief groove and wasting it.
After an oil film is formed on the inner peripheral surface in the circumferential direction and supports the bearing load, the lubricating oil in the areas where the pressure in the oil film is excessively high passes through the lubricating oil relief groove and axially spreads at both ends. Since the oil escapes to the conical surface, not only the thickness of the oil film and internal pressure are evened out in the circumferential direction, but also the oil film is formed everywhere in the axial direction, so the rotating shaft is securely supported at the center of the floating bearing. This prevents eccentric movement of the rotating shaft.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of the floating bearing according to the present invention, Figure 2 is an end view of the floating bearing in Figure 1 viewed from the direction of the arrow, and Figure 3 is a longitudinal sectional view of the floating bearing according to the present invention.
The figure is a diagram for explaining the action of the floating bearing of the present invention, and FIG. 4 is a diagram for explaining the conventional floating bearing. 10...Floating bearing, 12...
Housing, 16... Rotating shaft, 18... Lubricating oil supply passage, 20... Lubricating oil supply hole, 22... Lubricating oil escape groove.

Claims (1)

[Scope of utility model registration request] It is a hollow body with a cylindrical outer circumferential surface, and the inner circumferential surface facing the surface of the rotating shaft with a clearance left therein is widened to form a conical surface at both ends in the axial direction. , a lubricating oil supply hole penetrating radially between the inner circumferential surface and the outer circumferential surface, and an axial lubricating oil relief groove formed in the inner circumferential surface so that both ends thereof reach the conical surface. , a floating bearing characterized by being arranged circumferentially apart from each other so that they do not directly intersect.