JPS60101316A - Bearing - Google Patents

Abstract

PURPOSE:To enhance the bearing stiffness and load capacity by inserting foil in the bearing housing, forming a flap part at this foil, furnishing a spacer between this flap and bearing housing, and thereby forming a wedge-shaped space at the bearing surface by simple method. CONSTITUTION:Foil 3 is inserted in a space between a rotary shaft 1 and bearing housing 2, and one end of the foil is fixed to bearing housing 2 while the other end is left free. The foil 3 is provided with flaps 5 at certain spacings by forming flap-shaped notches 4 along the longitudinal direction. A spacer 6 is set in the space between the free end 5A of said flap 5 and the bearing housing facing thereto. This spacer 6 deflects the free end 5A of the flap 5 to the rotary shaft 1 side to form a wedge-shaped gap 7. The dynamic pressure generated from this wedge-shaped gap 7 supports the rotary shaft 1. A wedge-shaped space 8 at the back of the foil 3 acts as a damper through utilization of the flap 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a bearing, and particularly to a bearing suitable for a gas bearing that supports a high-speed rotating body.

[Background of the invention]

Conventionally, there are bearings in which wedge-shaped grooves, steps, groups, etc. are formed on the bearing surface to generate a larger fluid pressure in terms of bearing clearance, thereby improving high-speed stability and increasing load capacity. However, these wedge-shaped grooves, steps, groups, etc. generally have a depth in the range of several microns to several tens of microns, and require high precision of several microns or less. Conventionally, such bearing surfaces have been manufactured by machining or etching, but both require advanced technology and take a lot of time.

On the other hand, in order to form a wedge-shaped space that generates dynamic pressure, various bearings have been proposed that use foils, such as the one shown in US Pat. No. 3,511.544.

This foil-type bearing has been widely used in recent years due to its high-speed stability and low cost. However, one technical challenge for this foil bearing is to increase the rigidity load capacity.

[Purpose of the invention]

An object of the present invention is to provide a foil-type gas bearing that has excellent high-speed stability and high rigidity load capacity.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention inserts a thin foil into a bearing housing machined into a perfect circle, and makes tongue-shaped cuts corresponding to the required wedge-shaped gaps in the foil. forming a plurality of tongue-shaped portions, and installing a spacer having a thickness corresponding to the required depth between the back surface of the free end of the tongue-shaped portions and a bearing housing machined into a perfect circle;
A simple wedge-shaped gap is formed on the bearing surface.

[Embodiments of the invention]

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

FIG. 1 shows an embodiment of the bearing of the present invention. In the figure, ■ is a rotating shaft, 2 is a bearing housing, and 3 is a rotating shaft 1.
This is a foil inserted into the space between the bearing housing 2 and the bearing housing 2. One end of this foil 3 is fixed to the inner surface of the bearing housing 2, and the other end is a free end. As shown in FIGS. 2 and 3, the foil 3 is provided with tongues 5 formed by tongue-shaped cuts 4 at intervals along its longitudinal direction. A spacer 6 is provided between the free end 5A of the tongue 5 and the bearing housing 2 facing thereto. This spacer 6 bends the free end portion 5A of the tongue-like portion 5 toward the rotating shaft 1 side, and connects the free end portion 5A of the tongue-like portion 5
A wedge-shaped gap 7 is formed between the two. The dimensions and precision required for the gap are determined by the precision of the foil 3 and the spacer 6. By changing the thickness of the spacer 6, the shape of the wedge-shaped gap 7 can be changed as desired.

With this configuration, the rotating shaft can be supported by the dynamic pressure generated from the wedge-shaped gap 7. A wedge-shaped space 8 is also formed on the back surface of the foil 3, and as the tongue-shaped portion 5 bends with the vibration of the rotating shaft 1, the volume of the wedge-shaped space 8 changes, producing the effect of a damper. As a result, the rigidity load capacity can be increased.

In the above embodiment, the spacer 6 was used as a means to prevent the free end of the tongue 5 from bending, but as shown in the fourth @, the thickness of the spacer required at the tip of the tongue 5 was A required wedge-shaped gap may be formed by forming a thin wall portion 9 with a thin wall and bending it toward the back side of the tongue portion 5, or alternatively, as shown in FIG. A wedge-shaped space may be formed by forming a plating layer 10 corresponding to the spacer thickness on the back surface of the spacer. Furthermore, as shown in FIG.
Other portions 11 may be etched leaving a thickness for the spacer. Further, as shown in FIG. 7, the steps 12 for the spacers may be formed by plastic working.

FIG. 5 shows another embodiment of the bearing of the present invention, and in this figure, the same reference numerals as in FIGS. 1 to 3 are the same parts. In this embodiment, in order to add an elastic support structure to the bearing, the foils constituting the bearing surface are constructed in three layers. That is, the first layer foil 3 is exactly the same as that described in FIG. As shown in FIG. 9, on the back side of the foil 3, a foil 13 forming a second layer is installed as a supporting foil. Then, the second layer 13 is
It is supported by a foil 14 forming a layer. The third layer foil 14 elastically supports the second layer foil 13 with respect to the bearing housing 2 by a cantilever-shaped spring portion 14A formed by bending a part of the foil 14. The spring constant of the cantilever-shaped spring portion 14A is selected to be sufficiently smaller than the spring constant of the fluid film pressure generated in the bearing gap. Further, the pressing force applied to the rotating shaft 1 by the spring portion 14A is balanced with the fluid pressure generated in the bearing gap, that is, the wedge-shaped gap 7 at the rated rotation speed, and provides a preload effect.

With this configuration, even if the dimensions of the rotating shaft 1 and the bearing housing 2 change due to thermal deformation or the like, the spring portion 14A can absorb the change and continue stable rotation. As mentioned above, the spring constant of the spring portion 14A is sufficiently small compared to the spring constant of the bearing clearance.
Even if the thermal deformation is absorbed by the deformation of the spring portion 14A, the change in the pressing force applied to the rotary shaft 1, that is, the change in the bearing preload machine, is small, and the bearing performance does not change significantly as a result. Therefore, the bearing constructed as shown in FIG. 8 can maintain the initial front bearing performance even if subjected to thermal deformation, and can guarantee stable rotation.

〔Effect of the invention〕

According to the present invention, an accurate wedge-shaped gap can be formed in the bearing surface using a simple method, so that the bearing rigidity and load capacity can be increased. Therefore, costs can be reduced more than in the past. Further, since the wedge-shaped space formed between the foil forming the bearing surface and the housing functions as a damper for the bearing, the vibration limiting effect is increased and high-speed stability is therefore improved.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the bearing of the present invention, FIG. 2 is a developed view of the bearing surface of the embodiment of the bearing of the present invention shown in FIG. 1, and FIG. 3 is the same as shown in FIG. 1. A perspective view of a foil used in the bearing of the present invention, FIGS. 4 to 7 are views showing other examples of the spacer used in the present invention, and FIG. 8 is a front view showing another example of the bearing of the present invention. , FIG. 9 is a developed view of the bearing surface of another embodiment of the bearing of the present invention shown in FIG. 8. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Bearing housing, 3... Foil, 4... Tongue-shaped cut, 5... Tongue-shaped part, 6...
... Spacer, 7... Wedge-shaped gap, 8... Wedge-shaped gap, 9... Thin wall part, 13... Second layer foil,
14...Third layer foil, 14A...Spring part. Agent Patent Attorney Akio Takahashi] 4th B. Sai 51

Claims (1)

[Claims] 1. In a bearing in which a foil forming a bearing surface is provided inside a bearing housing and a rotating shaft is supported from this foil, one end of the foil is fixed inside the bearing housing, and the other end is fixed to the inside of the bearing housing. A free end is formed along the inside of the housing, tongue-like cuts are made in the longitudinal direction of the foil to form a plurality of tongues, and a plurality of tongues are formed between the back surface of the free end and the bearing housing. A wedge-shaped gap is formed in the bearing surface of the foil by installing a member that bends the free end toward the rotating shaft side, and a wedge-shaped gap is also formed between the foil forming the bearing surface and the bearing housing. bearings. 1. A bearing comprising: a foil forming a third layer; and a foil forming a third layer and having a spring portion contacting the bearing housing. 3. The bearing according to claim 1 or 2, wherein the member that bends the free end of the tongue toward the rotating shaft is a spacer. 4. In the bearing according to claim 1 or 2, the member that bends the free end of the tongue toward the rotating shaft is a member that is integrally provided on the back surface of the free end of the tongue. A bearing characterized by: