JPH0128337Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fluid bearing structure for gas, oil, water, steam, etc., and in particular a foil bearing structure that can exhibit excellent bearing performance by laminating elastic foils. Regarding.

[Prior art] Conventional hydrodynamic bearings have springs and dampers arranged in the components that support the bearing, and efforts have been made to stabilize bearing performance through the elastic action and vibration absorption action of these components. .

[Problems to be solved by the invention] However, none of the components used in the past had bearing parts or bearing surfaces that elastically deformed as a function of the rotational speed, and therefore The bearing characteristics were poor.

[Purpose of the invention] The purpose of the invention is to eliminate the above problems by spontaneously changing the basic form of the bearing.
In addition to improving bearing characteristics at startup, low speed, and high speed, it also reduces the number of component parts and improves machining and
The object of the present invention is to obtain an excellent foil bearing structure that is easy to assemble.

[Summary of the invention] The structure of the invention according to the above-mentioned purpose is to provide the elastic foil 4 with diagonal linear protrusions, and to wind this so that the linear protrusions 3, 3 on the inner layer side and the outer layer side are alternated. The laminated oil 4 is supported on the bearing surface 8 of the bearing case 7. As a result, in addition to the functions of a spring and a damper, the bearing part is given the function of automatically changing its pressure generation mechanism according to the rotation speed, so that it functions as a perfect round bearing at startup or low speed, and as a graven bearing at high speed. It is designed to function as a bearing.

[Embodiment] A first embodiment in which the present invention is applied to a conical oil bearing will be described below with reference to FIGS. 1 to 4.

As shown in FIG. 2, a large number of linear protrusions 3 are provided on the back surface 2 of a hollow disk 1 made of elastic foil.
The linear protrusions 3 are not processed in the width direction, that is, in the radial direction, of the hollow disk 1, but in an oblique direction that is deviated from the radial direction by an arbitrary angle β. In other words, it is processed not radially but spirally. They are integrally provided on the hollow disk 1 at equal pitches P, except for one location which is machined at a pitch of 1.5P in the circumferential direction. As shown in the figure, the hollow disk 1 is cut at one point to become a long piece, as shown in FIG.
When forming a 60° conical surface, start from cutting position C.
The above-mentioned linear protrusions 3 with a pitch of 1.5P are provided at 180° positions. These linear protrusions 3 can be obtained on the hollow disk 1 by known means such as photoetching.

As shown in FIG. 1, the foil 4 formed in this way is wound twice so that the foil back surface 2 provided with the linear protrusions 3 is directed outward in the radial direction. The foil 4a is formed into a conical shape with an angle of 60°, but due to this winding, the foil 4a becomes outward.
The foils 4b are laminated so that the linear protrusions 3 of the inner foil 4b are on the surface 5 between the linear protrusions 3, 3.
An engaging key 6 is attached to the outer end of the foil 4.
join.

The conically laminated foil 4 is housed in the conical bearing surface 8 of the bearing case 7 by engaging the key 6 in its keyway 9, as shown in FIG. When the foil 4 is reduced in diameter and stored in the bearing surface 8, it is placed at a position 180° from the cutting position C of the hollow disk 1.
Due to the position of the linear protrusions 3 machined with a 1.5P pitch, when the foils 4 are stacked in a double winding, the outward expansion force of the foils 4 in the radial direction causes the outer foils 4a and The linear protrusions 3, 3 are naturally out of phase by 1/2P pitch with respect to the inner foil 4b, and then stop. Therefore, when storing the laminated oil 4 in the bearing case, there is no need to adjust the pitch of the linear protrusions, and it is only necessary to insert the laminated oil 4 so that the diameter is slightly reduced. As a result of the outer and inner linear protrusions 3 being assembled with the 1/2P pitch shifted as described above, a large number of radial springs are arranged on the bearing surface 8 of the bearing case 7 in a circumferentially distributed manner. will be done.

Thus, the conical shaft 10 is inserted into the bearing case 7 containing the laminated oil 4, and this shaft 10
As shown in FIG. 1 or 3, the groove 11 formed between the linear protrusions 3 and 3 is rotated in the direction of the arrow so that the fluid is transmitted and concentrated on the axis.

Next, before explaining the operation of this embodiment with the above configuration, the general function of the conical surface oil bearing shown in FIG. 1 will be described.

Conical surface bearings have a structure that uses fluid film pressure generated along the conical surface to generate load capacity in the radial and axial directions, and are a single bearing that has both the functions of a journal bearing and a thrust bearing. be. If the half angle of the cone is θ and the sum of the fluid film pressures generated perpendicular to the conical surface is F, then the radial load capacity F _R and the axial load capacity F _T can be expressed by the following equations.

F _R =Fcosθ, F _T =Fsinθ Now, the operation of the conical surface foil bearing of this embodiment will be explained.

During startup and low rotation, the surface 5 of the inner foil 4b, which serves as a bearing surface, operates as a perfectly circular plain bearing, as shown in FIG. Plain bearings are a type with excellent load capacity and facilitate shaft flotation during start-up. Also, since it is a smooth surface,
It is superior in terms of low contact pressure and wear resistance. During high-speed rotation, the pressure of the fluid film generated in the bearing gap 12 becomes high, and the inner and outer foils 4a, 4b are elastically deformed into wave-like shapes as shown in FIG. The axial distribution of this wave-like deformation corresponds to the machining angle β of the linear protrusion 3 and is related to the generated pressure. As a result of wavy deformation due to the linear protrusions 3 arranged in a spiral,
A spiral groove-shaped bearing surface is created on the surface 5 of the inner foil 4b.

During this high-speed rotation, assuming that the bearing is a perfectly circular plain bearing, this bearing is of the type that generates pressure by a wedge film based on the eccentricity of the shaft 10, and when the shaft's own weight is constant, the diameter When the directional static load is constant, the eccentricity decreases and balance is achieved, but when the axial force increases, the eccentricity is small and a large load capacity cannot be achieved.

However, since the conical surface oil bearing of this example has a function as a spiral group bearing during high-speed rotation, it has an excellent pressure generation mechanism due to its pumping effect despite the decrease in eccentricity, and has an excellent pressure generation mechanism in both the radial and axial directions. Has high load capacity. especially,
High-speed turbomachinery generates high thrust force at high speeds because its shaft is lightweight and the radial load is small.

Therefore, according to the above-described embodiment, the laminated foil 4, which is the bearing portion, is elastically deformed as a function of the rotational speed, so that the bearing characteristics can be improved as much as possible during startup or low-speed rotation, and during high-speed rotation.

Further, by adopting the elastic foil structure, the bearing portion or the bearing surface can cope with the centrifugal expansion and thermal deformation of the shaft 10, making it possible to increase the temperature (low temperature) and speed, and has a high tolerance against the intrusion of foreign matter. Therefore, great advantages can be obtained by applying the present invention to all high-speed turbomachines that use fluid (gas, liquid) as a process fluid, such as turbochargers, turbo compressors, turbo expanders, turbo refrigerators, etc.
In particular, in the case of gas bearings, bearing loss is significantly reduced, making it possible to achieve high efficiency in turbomachinery and the like.

Note that the linear protrusions 3 of the foil 4 constituting the bearing part can be easily processed by photo etching, etc., and the laminated foil 4 can be stored by simply releasing the diameter-reduced state after inserting it into the bearing case 7. Assembly becomes extremely easy.

Figures 5 and 6 show a second embodiment in which the present invention is applied to a journal bearing, in which linear protrusions 23 are arranged in a herringbone shape on the back surface 22 of a band-shaped elastic foil 24. . According to this, unlike a conical surface foil bearing, it does not have the function of taking an axial load, but the surface 25 of the elastic foil 24 deforms into a herringbone shape at high speeds, and the bearing characteristics can be significantly improved.

[Effects of the invention] In summary, the present invention provides the following excellent effects.

(1) Since it operates as a plain bearing when starting up or at low speeds, it has excellent flying characteristics and is advantageous in terms of wear resistance.
Since it can exert a pumping effect as a group (spiral, herringbone, etc.) bearing, the load capacity is increased as much as possible.

(2) Since the bearing part can be constructed with a single piece of elastic foil, the number of parts can be significantly reduced and assembly is easy.Also, since the linear protrusions are provided integrally, it can be easily processed by photo etching, etc. It's easy.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the winding of the elastic foil when the present invention is applied to a conical bearing, Fig. 2 is a developed view of the elastic foil, Fig. 3 is an assembled cross-sectional view, and Fig. 4 is the same high-speed rotation. FIG. 5 is an explanatory diagram of the winding of the elastic foil when the present invention is applied to a journal bearing, and FIG. 6 is an expanded view of the same. In the figure, 2 and 22 are the back surfaces of the elastic foils, 3 and 2
3 is a linear protrusion, 4 and 24 are elastic foils, 4a is an outer elastic foil, 4b is an inner elastic foil, 5 and 25 are surfaces of the elastic foils, and 7 is a bearing case.

Claims (1)

[Scope of utility model registration request] Diagonal linear protrusions that intersect with the width direction are integrally provided on the back surface of a long elastic foil at approximately equal intervals in the length direction, and the back surface of the elastic foil provided with these linear protrusions is radially outward. The elastic foil is wound so that it is directed toward the outer side, and the layers are stacked so that the linear protrusions of the inner elastic foil are on the surface between the linear protrusions of the outer elastic foil due to this winding. A foil bearing structure characterized in that the laminated foil is housed in a bearing case.