JPH0532654Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the improvement of hydrodynamic hydrodynamic bearings that use liquid or gas as a lubricant and are used as bearings in high-speed rotating equipment such as turbochargers and expansion turbines. .

[Prior Art] As shown in Japanese Unexamined Patent Publication No. 61-74910, a cylindrical bearing surface has a bearing case in which band-shaped elastic foils are wound multiple times and a rotary shaft is rotatably supported on the inner peripheral surface of the bearing case. A foil journal bearing is already known in which a bearing body having a shape of 100 mm is attached using its own elastic force.

This foil journal bearing combines the spring function of the elastic foil itself, the squeeze damper function between the laminated elastic foil layers, and the Coulomb friction function, and is highly stable when the rotating shaft rotates at high speed.

[Problems to be solved by the invention] However, in conventional foil journal bearings, vibrations that cannot be damped between the inner layer and the outer layer of the elastic foil are transmitted to the bearing case, and the vibration is still insufficient. There was a problem that high-speed stability could not be expected.

Therefore, the purpose of this invention is to solve the above problems,
An object of the present invention is to provide a foil journal bearing that dramatically improves high-speed stability.

[Means for Solving the Problems] In order to achieve the above object, the present invention wraps a band-shaped elastic foil having spacer protrusions on its surface in multiple layers inside the bearing case, and attaches the rotating shaft to the inner peripheral surface of the band-shaped elastic foil. In a foil journal bearing, which is formed by fitting a bearing body formed with a cylindrical bearing surface that supports the rotatably with its own elastic force, a wire is finely woven between the bearing case and the bearing body. It is characterized by interposing a buffer sleeve made by winding a band-shaped wire mesh into a cylindrical shape and compressing it to the extent that elasticity in the radial direction remains.

[Operation] Effective external damping is added to the elastic foil due to the large damping ability due to the spring function and Coulomb friction function of the buffer sleeve made of multiple layers of wire mesh. As a result, vibrations that cannot be damped completely between the inner layer and the outer layer of the elastic foil can be sufficiently damped.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

In FIG. 1 showing a foil journal bearing, reference numeral 1 denotes a bearing case having a cylindrical shaft hole 2, into which a buffer sleeve 3 is fitted. This buffer sleeve 3 is made by winding a belt-shaped wire mesh (trade name: Nittomesh Wire) 4 made of finely woven wire into a cylindrical shape and compressing it to the extent that elasticity in the radial direction remains. It is molded to a size that can fit exactly into the inner circumferential surface of the shaft hole 2. Note that the springiness of the buffer sleeve 3 is matched in order with the gas film rigidity of the squeeze damper.

Inside this buffer sleeve 3, a bearing body 8, which has a cylindrical bearing surface 7 that rotatably supports a rotary shaft 6 on its inner circumferential surface by wrapping an elastic foil 5 in multiple layers, uses its own elastic force. It is fitted. As shown in FIG. 2, this elastic foil 5 is made of a strip-shaped stainless steel plate or the like having a predetermined width L and length nDπ, and on one side thereof linear protrusions 9 for spacers that cross the width direction are arranged at appropriate pitches in the longitudinal direction. It is integrally formed of P by multiple etching processes. Note that n is the number of turns, D is the inner diameter of the buffer sleeve 3, and FIG. 1 illustrates the case where n=3. The bearing body 8 is constructed by winding the elastic foil 5 so that the protrusions 9 thereof face outward and the protrusions 9 of the next inner layer are located between the protrusions 9 of the outer layer.

In addition, the size of the mesh of the wire mesh 4 that constitutes the buffer sleeve 3, the material and thickness of the wire, the degree of compression, the thickness t of the elastic foil 5, the width w, the height h, and the pitch P of the protrusion 9 are the same as those of the foil bearing. It is arbitrarily determined depending on the desired springiness and damping properties.

A rotating shaft 6 having an outer diameter smaller than its inner diameter is supported on the bearing surface 7 of the bearing body 8, and as the rotating shaft 6 rotates, the lower surface in the direction of gravity and the bearing surface 7 are supported.
By forming a wedge film 10 of lubricating oil or air between them, the bearing surface 7 rotates while floating above the bearing surface 7.

According to this configuration, the squeeze damper function, which is generated when the chamber 11 formed by the projections 9 between the layers of the elastic foil 5 constituting the bearing body 8 is compressed from the radial direction, and the contact between the projections 9 The Coulomb friction function caused by friction and the spring function of the elastic foil 5 itself are exhibited to prevent the occurrence of self-excited vibrations that tend to occur at high speed rotation. In addition, the buffer sleeve 3 formed by wrapping the wire mesh 4 exhibits a large damping ability due to the spring function and Coulomb friction, and therefore sufficiently damps vibrations that cannot be damped between the inner layer and the outer layer of the elastic foil 5. This dramatically improves high-speed stability.

In addition, the pitch P of the protrusions 9 of the elastic foil 5 in the above embodiment is not necessarily constant, and the elastic foil 5 has protrusions 9 alternately formed on both sides, or the protrusions 9 are formed in the range where the bearing surface 7 is formed.
It may be something that does not form.

[Effects of the invention] In summary, the invention exhibits the following excellent effects: A wire mesh made of finely woven wire is wound into a cylindrical shape between the bearing case and the bearing body made of elastic foil. Since a compression-molded buffer sleeve is provided to retain elasticity in the direction, it is possible to sufficiently attenuate vibrations that cannot be damped between the inner layer and the outer layer of the elastic foil.
High-speed stability is dramatically improved.

Since the buffer sleeve is made of wire mesh, it is not only resistant to high temperatures but also has excellent heat dissipation properties, making it particularly suitable as a bearing structure for high-speed rotating equipment that easily overheats.

[Brief explanation of the drawing]

FIG. 1 is an assembled sectional view of a foil journal bearing according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the elastic foil shown in FIG. 1. In the figure, 1 is a bearing case, 2 is a shaft hole, 3 is a buffer sleeve, 5 is an elastic foil, 6 is a rotating shaft, 7 is a bearing surface, 8 is a bearing body, and 9 is a protrusion.

Claims (1)

[Scope of utility model registration request] Inside the bearing case, a band-shaped elastic foil with spacer protrusions on the surface is wound multiple times, and the bearing body has a cylindrical bearing surface that rotatably supports the rotating shaft on its inner circumferential surface. In the foil journal bearing, a wire mesh made of finely woven wire is wrapped in a cylindrical shape between the bearing case and the bearing body, and compression molded to the extent that elasticity in the radial direction remains. A foil journal bearing characterized by having a buffer sleeve interposed therein.