JP2008241015A - Multirobe foil fluid bearing and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multirobe foil fluid bearing capable of supporting a journal by an excellent fluid lubricating film causing neither the increase of friction and wear at the start nor the fall of load capacity. <P>SOLUTION: The entire length of a circular arc face part 45 formed by connecting adjacent vertex parts 44 is formed to bulge onto the bearing holding member 30 side. Consequently, since an inflection point is not formed as before at the circular arc face part 45 constituting the bearing sliding face of a foil 40, a part with which the journal 20 comes in strong contact at the start is eliminated to suppress the increase of friction and wear and the fall of load capacity of the fluid bearing. Further, since excellent wedge shape narrowed toward the end can be formed from the vertex part 44 forming a large clearance part 51 during rotation to a small clearance part 52, a fluid lubricating film is easily formed to enlarge the load capacity of the bearing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention comprises a bearing holding member that surrounds the outer periphery of a journal via a gap, a bearing sliding surface that is disposed in the gap and faces the journal, and a plurality of vertex portions and a plurality of vertex portions. A viscoelastic body or elasticity filled in a gap between a multi-arc closed-loop foil having a plurality of arc surface portions formed by connecting adjacent apex portions and the bearing holding member facing the foil. The present invention relates to a multi-arc foil fluid bearing comprising a body or a composite of a viscoelastic body and an elastic body and supporting the journal by a fluid lubricating film formed by relative rotation of the journal and the bearing sliding surface. .

  The multi-arc foil fluid bearing having the above-described configuration is disclosed in Japanese Patent Laid-Open No. 2005-299922 (Patent Document 1) previously proposed by the present applicant.

  The structure of the multi-arc foil fluid bearing described in Patent Document 1 is as shown in FIG. 5, the multi-arc foil fluid bearing 1 constitutes a bearing holding member 3 that surrounds the outer periphery of the journal 2 via a gap, and a bearing sliding surface that is disposed in the gap and faces the journal 2. Alternatively, a multi-arc closed-loop foil 4 having a plurality of apex portions 4a and a number of bulging arcuate surface portions 4b corresponding to the number of the apex portions 4a, and a gap between the foil 4 and the bearing holding member 3 The viscoelastic body 6 (or an elastic body or a composite body of a viscoelastic body and an elastic body) filled with a fluid lubrication film formed by relative rotation of the journal 2 and the bearing sliding surface to the journal 2. Support. The arc surface portion 4b described above refers to an arc portion of the foil 4 corresponding to the diameter D of the journal 2 when the journal 2 is arranged coaxially with the foil 4. Further, a gap C <b> 1 is formed between the apex 4 a and the inner peripheral surface of the bearing holding member 3.

The purpose of the multi-arc foil fluid bearing 1 having the above-described structure is to wear particles generated by contact between the journal 2 and the bearing sliding surface when starting and stopping because the wedge-like fluid lubricating film is easily formed and the bearing load capacity is large. Is easy to be discharged from the bearing sliding surface. In addition, the bearing clearance can be easily set at the time of manufacture, and the manufacture and assembly are simple, which is also suitable for supporting a small-diameter journal 2.
Japanese Patent Laying-Open No. 2005-299922 (FIG. 1)

  Therefore, the multi-arc foil fluid bearing 1 having the structure shown in FIG. 5 is used as, for example, a journal bearing of a magnetic disk drive motor, a polygon mirror scanner motor, or a color wheel motor of a rear projection television. When forming the foil 4 having a shape, the ends of a plurality of foil thin plates are overlapped and bonded together by welding or the like, and the inner loop space is expanded by a jig simulating the journal bearing 2 to bulge from the apex 4a. In order to form the arc surface portion 4b, a bend portion 4c that bulges in a direction opposite to the bulge direction of the arc surface portion 4b is formed between the apex portion 4a and the arc surface portion 4b, and a part of the arc surface is a journal bearing. 2 is convex toward the bearing holding member 3 side. For this reason, the thickness of the fluid film is the thinnest at the inflection portion 4c, and it is difficult to form a wedge-shaped fluid film.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a multi-arc foil fluid bearing capable of increasing the load capacity by forming a good fluid lubricating film and a method for manufacturing the same. There is to do.

  Means employed by the invention according to claim 1 will be described with reference to the drawings. As shown in FIG. 1, a bearing holding member 30 that surrounds the outer periphery of the journal 20 via a gap, and the gap is disposed in the gap. It has a bearing sliding surface facing the journal 20 and has a plurality of vertex portions 44 and a plurality of arcuate surface portions 45 formed by connecting adjacent vertex portions 44 of the plurality of vertex portions 44. A multi-arc closed-loop foil 40 and a viscoelastic body 60 (or an elastic body or a composite of a viscoelastic body and an elastic body) filled in a gap between the bearing holding member 30 facing the foil 40. In the multi-arc foil fluid bearing 10 that is configured and supports the journal 20 by a fluid lubricating film formed by relative rotation between the journal 20 and the bearing sliding surface, the adjacent apex portions 44 are The total length of the circular surface 45 formed by sintering is characterized in that as a shape that bulges to the bearing holding member 30 side.

  The means employed by the invention according to claim 2 will be described with reference to the drawings. As shown in FIG. 2, in the multi-arc foil fluid bearing 10 according to claim 1, the connection structure of the apex portion 44 is as follows. , One end of the foil thin plate 41 constituting one arcuate surface portion and the other end of the foil thin plate 41 constituting the other arcuate surface portion are connected by engagement. Here, the engagement means that one thin plate is connected by being inserted into the other thin plate.

  Further, the means employed by the invention according to claim 3 will be described with reference to the drawings. As shown in FIG. 4, the bearing holding member 30 that surrounds the outer periphery of the journal 20 via a gap is disposed in the gap. A plurality of arcuate surface portions 45 formed by connecting a plurality of apex portions 44 and adjacent apex portions 44 of the plurality of apex portions 44. And a viscoelastic body 60 (or an elastic body or a composite of a viscoelastic body and an elastic body) filled in a gap between the foil 40 and the bearing holding member 30 facing the foil 40. In the manufacturing method of the multi-arc foil fluid bearing 10 configured to support the journal 20 with a fluid lubricating film formed by relative rotation between the journal 20 and the bearing sliding surface, A plurality of apex portions 44 formed by engaging end edges of the flat foil thin plate 41 and a plurality of surfaces formed by connecting adjacent apex portions 44 of the plurality of apex portions 44. A first step of manufacturing the closed-loop foil 40 having an assembly jig in which a positioning 103 of the bearing holding member 30 is formed and a shaft column 102 imitating the journal shaft is erected in the center of the base board 101 100, the inner loop space of the closed-loop foil 40 manufactured in the first step passes through the shaft column 102 so that the entire length of the surface bulges toward the bearing holding member 30. A second step of forming the bulging arcuate surface portion 45 in the third step, a third step of fitting the bearing holding member 30 into the positioning 103 of the base board 101 of the assembly jig 100, the foil 40 and the The fourth step of filling the gap between the holding member 30 and the viscoelastic body 60 (or the elastic body or the composite body of the viscoelastic body and the elastic body) and the multi-arc foil fluid bearing 10 from the assembly jig 100. And a fifth step to be removed.

  In the invention according to claim 1, the entire length of the arcuate surface portion 45 formed by connecting the adjacent apex portions 44 is formed to bulge toward the bearing holding member 30 side. Since the inflection point is not formed in the circular arc surface portion 45 constituting the moving surface as in the prior art, the portion where the journal 20 is in strong contact at the time of startup is eliminated, and the increase in friction and wear and the decrease in the load capacity of the fluid bearing are suppressed. can do. Further, the bearing gap 50 between the foil 40 and the journal 20 can form a good narrowed wedge shape from the apex 44 constituting the large gap 51 to the small gap 52, so that the fluid lubricating film is formed. It is easy to form and the load capacity of the bearing can be increased.

  Moreover, in the invention which concerns on Claim 2, one end part of the foil thin plate 41 which comprises one circular arc surface part of the vertex part 44, and the other end part of the foil thin plate 41 which comprises the other circular arc surface part are engaged by engagement. By connecting, when the surface of the foil thin plate 41 is an arc surface, it is possible to easily form the arc surface portion 45 in which the entire peripheral surface having no inflection point bulges out.

  Further, in the invention according to claim 3, a plurality of flat portions formed by connecting the apex portions 44 formed by engaging the edges of the flat foil thin plates 41 and the adjacent apex portions 44 are formed. The closed loop foil 40 having a surface and the bearing holding member 30 are mounted on the assembly jig 100, and the viscoelastic body 60 (or the elastic body or the viscoelastic body is placed in the gap between the foil 40 and the bearing holding member 30. It is possible to manufacture the multi-arc foil fluid bearing 10 according to the present invention by simply filling the elastic composite) and removing the multi-arc foil fluid bearing 10 from the assembling jig 100, and manufacturing and assembling the foil 40. In addition to being simple, the multi-arc foil fluid bearing 10 in which the bearing clearance can be easily set can be manufactured, and a manufacturing method suitable for mass production can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. FIG. 1 is a cross-sectional view of a multi-arc foil fluid bearing according to the first embodiment, and FIG. 2 is a front view (A) of a thin foil sheet and an assembled perspective view showing a connecting structure of foils used in the first embodiment. FIG. 4B is an explanatory diagram for explaining a manufacturing process of the multi-arc foil fluid bearing according to the first embodiment.

  The multi-arc foil fluid bearing 10 according to the first embodiment includes a bearing holding member 30 that surrounds the outer periphery of the journal 20 via a gap, a bearing sliding surface that is disposed in the gap and faces the journal 20, and includes three pieces. A multi-arc foil 40 having a multi-arc closed-loop shape having a vertex 44 and three arc-shaped surface portions 45 formed by connecting adjacent vertexes 44 of the three vertices 44, and the multi-arc foil 40 and a viscoelastic body 60 (or an elastic body or a composite of a viscoelastic body and an elastic body) filled in a gap between the bearing holding member 30 and the bearing holding member 30 facing each other. The journal 20 is supported by a fluid lubricating film formed by relative rotation between the journal 20 and the bearing sliding surface.

  As shown in FIG. 2A, the multi-arc foil 40 is a flat foil thin plate having an engagement cut groove 42 formed at one end and an engagement protrusion 43 formed at the other end. As shown in FIG. 2B, the three foil thin plates 41 are engaged with each other, and the foil thin plates 41 adjacent to the engagement cut grooves 42 of one foil thin plate 41 are prepared. By inserting and engaging the projecting pieces 43, a triangular closed-loop foil 40 is formed. Further, at the engagement portion between the engagement cut groove 42 and the engagement protrusion 43, the coupling between the three foil thin plates 41 is strengthened and the flow into the bearing sliding surface is filled when the viscoelastic body 60 is filled. In order to prevent this, an adhesive may be applied. The foil 40 is made of a metal thin plate such as stainless steel, phosphor bronze, brass, copper, or aluminum, or a resin thin plate such as PTFE (polytetrafluoroethylene), and has a thickness of 10 to 500 μm.

  Then, the closed loop foil 40 configured as described above is assembled to the bearing holding member 30 by the assembly jig 100 shown in FIG. The assembling jig 100 is configured such that a shaft column 102 simulating a journal 20 is erected at the center of a base board 101 in which a positioning recess 103 that matches the outer dimensions of the bearing holding member 30 is formed. It is. The positioning of the bearing holding member 30 and the assembling jig 100 is not limited to the above-described example, and there is a method of assembling the assembling jig 100 using the inner diameter of the bearing holding member 30 or a knock pin.

  Next, as shown in FIGS. 4B and 4C, the inner loop space of the closed loop multi-arc foil 40 is passed through the shaft column 102 of the assembly jig 100. The diameter of the shaft column 102 simulating the journal 20 is substantially the same as the diameter of the journal 20 to be applied, but it is desirable that the diameter be such that a predetermined bearing gap 50 is formed. Thereafter, after the bearing holding member 30 is mounted in the recess 103 of the base board 101, an appropriate amount of the viscoelastic body 60 is filled in the gap between the multi-arc foil 40 and the bearing holding member 30 with the rubber band 110 wound around, and cured. . After curing, the multi-arc foil fluid bearing 10 can be completed by removing it from the assembling jig 100. As the viscoelastic body, a rubber material such as silicone or acrylic or a polymer gel is used. Moreover, it may replace with a viscoelastic body and may use the elastic body which consists of a spring and a wave-like foil, and also may use the composite_body | complex which combined said viscoelastic body and an elastic body.

  When the journal 20 is supported on the multi-arc foil fluid bearing 10 manufactured as described above, a predetermined bearing gap 50 is provided between the journal 20 and the bearing sliding surface of the multi-arc foil 40. The distribution of the bearing gap 50 is the largest in the large gap portion 51 in the vicinity of the apex portion 44 and the smallest in the small gap portion 52 in the almost middle portion between the two apexes. Further, the bearing gap 50 is generally designed to be about 3/1000 or less of the diameter of the journal 20 with the small gap portion 52 at the smallest portion, and the actual bearing gap 50 is 10 μm or less at most. . In order to reduce the rotational vibration of the journal 20, the bearing gap 50 may be set small. In the multi-arc foil fluid bearing 10 in the first embodiment (the same applies to other embodiments described in detail later), the multi-arc foil 40 and the viscoelastic body 60 that supports the multi-arc foil 40 even when there is almost no bearing gap 50 when stationary. Due to this elastic effect, the fluid lubrication film can be formed and the journal 20 can be floated at a certain rotational speed or higher. In FIG. 1, the thickness of the multi-arc foil 40 and the bearing gap 50 are exaggerated for easy understanding.

  Thus, the operation of the multi-arc foil fluid bearing 10 configured as described above will be described. When the journal 20 rotates, fluid is drawn from the vicinity of the large gap portion 51 near the apex portion 44, and the gap shape is narrowed. A fluid lubricating film is generated toward the small gap portion 52. The restoring force and damping force of the fluid lubricating film and the viscoelastic body 60 can support and damp unbalanced vibrations associated with the rotation, thereby realizing stable high-precision rotation. In this case, since the inflection point is not formed in the arc surface portion 45 constituting the bearing sliding surface of the multi-arc foil 40 as in the prior art, the portion where the journal 20 is in strong contact at the time of start-up is eliminated, and friction / wear is not generated. The increase can be suppressed, and the load capacity as a fluid bearing can be increased. The structure is such that the wear powder generated on the bearing sliding surface due to the direct contact between the journal 20 and the bearing sliding surface when starting or stopping the rotation is easily discharged to the outside from the large gap portion 51 near the apex portion 44. Therefore, stable bearing performance can be maintained for a long time.

  In the first embodiment described above, the connecting structure in the apex portion 44 for configuring the arcuate surface portion 45 of the multi-arc foil 40 is configured by the engagement cut groove 42 and the engagement protrusion 43. A connecting structure other than this connecting structure may be used. An embodiment adopting such another connecting structure will be described with reference to FIG. FIG. 3: is sectional drawing (A) of the multi-arc foil fluid bearing which concerns on 2nd Embodiment, and the front view (B) of the foil thin plate.

  First, in FIG. 3, the multi-arc foil fluid bearing 10 according to the second embodiment is different from the multi-arc foil fluid bearing 10 according to the first embodiment only in the configuration of the multi-arc foil 80 constituting the bearing sliding surface. The other configurations are the same. Therefore, as shown in FIG. 3B, the multi-arc foil 80 according to the second embodiment includes an upper engagement groove 82 and other portions which are slit at one end portion from the top to the middle along the end side. Five flat foil thin plates 81 having a bottom engaging groove 83 formed in a slit from the bottom to the middle along the edge are prepared at the end, and for the five foils. As shown in FIG. 3A, by inserting and engaging the lower engagement groove 83 of the foil thin plate 81 adjacent to the upper engagement groove 82 of one foil thin plate 81 between the thin plates 81, a pentagonal shape is obtained. A foil 80 having a shape is formed. Further, at the engaging portion between the upper engaging groove 82 and the lower engaging groove 83, the coupling between the five foil thin plates 81 is strengthened, and the flow into the bearing sliding surface is filled when the viscoelastic body 60 is filled. In order to prevent this, an adhesive may be applied. Also in the multi-arc foil fluid bearing 10 according to the second embodiment configured as described above, the five apex portions 84 and the inner peripheral loop surface connecting the five apex portions 84 are outside the entire length. The multi-arc foil 80 is a circular arc surface portion 85 that bulges toward the center. That is, the connection structure at the apex portion 84 of the multi-arc foil 80 is not an adhesion structure by welding or the like as in the prior art, but is an engagement apex portion due to the engagement between the upper engagement groove 82 and the lower engagement groove 83. Therefore, the inner peripheral loop surface of the foil thin plate 81 becomes an arcuate surface portion 85 that bulges toward the bearing holding member 30 side having no inflection point over its entire length. Note that two or more foil thin plates may be used as the multi-arc foil having the engagement apex portion formed by the engagement between the upper engagement groove 82 and the lower engagement groove 83.

  As mentioned above, although the embodiment in the present invention has been described in detail, various design changes can be made without departing from the spirit of the present invention. For example, the number of vertices of the foil 41 is not limited to 2-5. Further, in the multi-arc foil fluid bearing 10 according to the present invention, it is necessary to reduce friction and wear between the foils 40 and 80 and the journal 20 at the time of starting or stopping or at the time of low rotation. For this purpose, at least one of the outer peripheral surface of the journal 20 and the inner peripheral surface of the foils 40, 80 is made of chromium plating, DLC (diamond-like carbon) hard coating, PTFE (polytetrafluoroethylene), MoS2 having excellent friction characteristics. It is desirable to apply a solid lubricant coating such as (molybdenum disulfide).

  Further, in the multi-arc foil fluid bearing 10 according to the present invention, high-precision rotation at high speed (10,000 rpm or more) can be achieved with gas lubrication that does not require an air supply mechanism. It is suitable for application as a bearing of a polygon mirror scanner motor or a color wheel motor of a rear projection television. In addition, in the multi-arc foil fluid bearing according to the present invention, the lubricating fluid can be applied to the case of water-based or oil-based liquid in addition to gas.

  In the embodiment described above, the case where the journal 20 is rotated and the foils 40 and 80, the viscoelastic body 60 and the bearing holding member 30 which are bearing sliding surfaces are stationary has been described. The multi-arc foil fluid bearing 10 can be applied even when the journal 20 is stationary and the foils 40 and 80, the viscoelastic body 60, and the bearing holding member 30 are rotated.

It is sectional drawing of the multi-arc foil fluid bearing which concerns on 1st Embodiment. It is the front view (A) and assembly perspective view (B) of the thin plate for foil which show the connection structure of the foil used for 1st Embodiment. It is sectional drawing (A) of the multi-arc foil fluid bearing which concerns on 2nd Embodiment, and the front view (B) of the foil thin plate. It is explanatory drawing for demonstrating the manufacturing process of the multi-arc foil fluid bearing which concerns on 1st Embodiment. It is sectional drawing of the conventional multi-arc foil fluid bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Multiarc foil fluid bearing 20 Journal 30 Bearing holding member 40 Multiarc foil 41 Thin foil plate 42 Engagement groove 43 Engagement protrusion 44 Apex part 45 Arc surface part 50 Bearing gap 51 Large gap part 52 Small gap part 60 Viscoelasticity Body 80 Multi-arc foil 81 Thin foil plate 82 Upper engagement groove 83 Lower engagement groove 84 Vertex portion 85 Arc surface portion 100 Assembly jig 101 Base plate 102 Shaft column 103 Recess (Positioning)

Claims (3)

A bearing holding member that surrounds the outer periphery of the journal via a gap, a bearing sliding surface that is disposed in the gap and faces the journal, and a plurality of vertex portions and adjacent vertex portions of the plurality of vertex portions A viscoelastic body, an elastic body, or a viscoelasticity filled in a gap between a multi-arc closed-loop foil having a plurality of circular arc surface portions formed by connecting together, and the bearing holding member facing the foil In a multi-arc foil fluid bearing comprising a composite body and an elastic body, and supporting the journal by a fluid lubricating film formed by relative rotation of the journal and the bearing sliding surface,
A multi-arc foil fluid bearing characterized in that an arcuate surface portion formed by connecting the adjacent apex portions has a shape bulging toward the bearing holding member.   The plurality of apex portions are formed by engaging one end portion of a foil thin plate constituting one arcuate surface portion and a foil thin plate constituting the other arcuate surface portion by engagement. The multi-arc foil fluid bearing according to claim 1. A bearing holding member that surrounds the outer periphery of the journal via a gap, a bearing sliding surface that is disposed in the gap and faces the journal, and a plurality of vertex portions and adjacent vertex portions of the plurality of vertex portions A viscoelastic body, an elastic body, or a viscoelasticity filled in a gap between a multi-arc closed-loop foil having a plurality of circular arc surface portions formed by connecting together, and the bearing holding member facing the foil In a method of manufacturing a multi-arc foil fluid bearing comprising a composite of a body and an elastic body, and supporting the journal by a fluid lubricating film formed by relative rotation between the journal and the bearing sliding surface,
A plurality of vertex portions formed by engaging edges of a plurality of flat foil thin plates and a plurality of surfaces formed by connecting adjacent vertex portions of the plurality of vertex portions; A first step of producing the foil in a closed loop;
The assembly of the closed-loop foil produced by the first step is performed using an assembly jig in which positioning with the bearing holding member is formed and a shaft column simulating the journal shaft is erected in the center of the base board. A second step of forming a bulging arcuate surface portion so that the entire length of the surface bulges toward the bearing holding member through an inner loop space through the shaft column;
A third step of inserting the bearing holding member into the positioning of the base board of the assembly jig;
A fourth step of filling a gap between the foil and the bearing holding member with a viscoelastic body or an elastic body or a composite of a viscoelastic body and an elastic body;
A fifth step of removing the multi-arc foil fluid bearing from the assembly jig;
A method of manufacturing a multi-arc foil fluid bearing, comprising:

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