JP2013060988A - Cylindrical roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a solid lubricant to be sufficiently transferred even to an end surface of a roller in a cylindrical roller bearing used in cryogenic fluid.SOLUTION: The cylindrical roller bearing includes an inner ring 12, an outer ring 13, many cylindrical rollers 16 interposed between raceway surfaces 14 and 15 thereof, and a retainer 17 for holding the rollers 16 at fixed intervals. The retainer 17 is made of a material containing a solid lubricant. A lubrication ring 26 containing the solid lubricant is interposed between the flange 20 of the outer ring 13 on the fixed side and the roller 16.

Description

  The present invention relates to a cylindrical roller bearing, and more particularly to a cylindrical roller bearing used in a cryogenic fluid of a turbo pump for a liquid rocket engine.

  Since the bearings (angular ball bearings) used in current liquid rocket engine turbo pumps are used in cryogenic fluids in liquid hydrogen and liquid oxygen, lubrication with lubricating oil or grease cannot be employed. For this reason, a cage is formed of a composite material in which a glass woven fabric is impregnated with PTFE (polytetrafluoroethylene), which is a solid lubricant, and the rolling element slidingly contacts the pocket of the cage during rotation, and the rolling element Lubrication is carried out by transferring a solid lubricant to the raceway surface of the raceway in contact (Patent Document 1).

  In this case, since the transfer of the solid lubricant from the cage is insufficient immediately after the start of operation, the lubricity at the initial stage of the operation is formed by forming a coating film of the solid lubricant by sputtering on the rolling elements and the raceway surface in advance. (Non-patent Document 1)

JP 2006-57744 A

"Lubrication characteristics of cage composite materials for rocket turbo pump bearings" Masataka Nosaka Journal of Japan Society for Composite Materials Vol. 20, No. 6, 1944 (2. Turbo pump and bearing)

  In a liquid rocket engine turbo pump, it is necessary to improve the radial rigidity of the bearing in order to improve performance and reliability. However, a conventionally used angular ball bearing cannot be improved significantly. Therefore, cylindrical roller bearings with high radial rigidity are used.

  However, simply applying the conventional lubrication means employed in angular ball bearings to cylindrical roller bearings as it is, it is not possible to positively transfer the solid lubricant to the roller end surfaces. There is a problem of insufficient lubrication between the collars of the facing races.

  Accordingly, an object of the present invention is to provide a cylindrical roller bearing having a structure capable of sufficiently transferring a solid lubricant to the end face of the roller.

  In order to solve the above-mentioned problems, the present invention comprises an inner ring, an outer ring, a large number of cylindrical rollers interposed between these raceway surfaces, and a cage that holds each roller at a predetermined interval. In the cylindrical roller bearing formed of a material containing solid lubricant, a configuration in which a lubrication ring containing solid lubricant is interposed between the flanges of the stationary-side raceway ring is adopted.

  When the roller contacts the pillar portion of the cage, the solid lubricant is transferred to the rolling surface of the roller, and the solid lubricant is transferred to the raceway surface of the inner and outer rings as the roller rotates.

  It is desirable to adopt a configuration in which a fixing ring is interposed between the collar of the fixed-side raceway ring and the lubricating ring. The fixing ring can suppress the axial warping of the lubricating ring, and the contact between the end face of the roller and the lubricating ring is ensured.

  The posture of the fixing ring can be stabilized by closely fitting the fixing ring in a fitting groove provided between the lubricating ring and the collar. When the width of the fixing ring is smaller than the width of the fitting groove, the fixing ring can be stabilized by interposing an elastic body such as a disc spring between the fitting groove and the collar. The configuration in which the elastic body is interposed is effective in preventing warpage of these parts when the width of the fixing ring or the lubricating ring is narrow and the rigidity is low.

  As described above, according to the present invention, in a cylindrical roller bearing in which lubrication means using lubricating oil or grease cannot be employed by being used in a cryogenic fluid such as liquid hydrogen or liquid oxygen, the roller rolling Solid lubricant can be positively transferred not only to the surface but also to the end face of the roller.

FIG. 1 is a cross-sectional view of the cylindrical roller bearing of the first embodiment. FIG. 2 is a partially enlarged sectional view of the above. FIG. 3 is a partially enlarged plan view of the cage part of the above. FIG. 4 is a perspective view of the same fixing ring. FIG. 5 is a partially enlarged sectional view of the above. FIG. 6 is a combined sectional view of the above-described cylindrical roller bearing and axial ball bearing. FIG. 7 is a partial cross-sectional view of the cylindrical roller bearing of the second embodiment. FIG. 8 is a partially enlarged sectional view of the above.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
[Embodiment 1]

  A cylindrical roller bearing 11 according to the first embodiment shown in FIGS. 1 and 2 includes an inner ring 12 and an outer ring 13 similar to those in a normal case, and a large number of cylindrical rollers 16 interposed between the raceway surfaces 14 and 15. And an inner ring rotating cylindrical roller bearing provided with a retainer 17 that holds the rollers 16 at regular intervals.

  The cage 17 is an inner ring guide type rotated in contact with the inner ring 12, and is formed by a composite material in which a glass woven fabric is impregnated with a solid lubricant having a self-lubricating property such as PTFE. As shown in FIG. 3, the retainer 17 is composed of an annular portion 17a on both sides in the axial direction and a column portion 17b having a constant interval for connecting the annular portions 17a to each other. A large number of pockets 18 surrounded by the portion 17b are provided at equal intervals in the circumferential direction. The roller 16 is accommodated in the pocket 18, both end surfaces 19 of the roller 16 are in contact with the annular portion 17a, and the rolling surface 21 is in contact with the column portion 17b.

  As shown in FIG. 2, flanges 22 are provided on both sides of the raceway surface 14 of the inner ring 12 so as to rise in the outer diameter direction. The height of the collar 22 from the raceway surface 14 is assumed to be x1. A step surface 23 in the outer diameter direction is provided on both sides of the raceway surface 15 of the outer ring 13, and a mounting surface 24 whose diameter is increased by the step surface 23 is provided. A fitting groove 25 is provided between the mounting surface 24 and the collar 20 of the outer ring 13.

  A lubrication ring 26 is interposed in a corner portion formed by the step surface 23 and the mounting surface 24. The lubricating ring 26 is formed of a solid lubricant having self-lubricating properties such as PTFE. Further, when higher strength is required, it may be formed of a composite material in which a glass woven fabric is impregnated with the above-described solid lubricant. The axial width of the mounting surface 24 is formed to match the width of the lubricating ring 26, and the fixing ring 27 accommodated in the fitting groove 25 is in close contact with the lubricating ring 26. The fixing ring 27 is formed by a split ring (see FIG. 4).

  The inner diameter of the lubrication ring 26 is set to a size protruding from the raceway surface 15 of the outer ring 13 to the inner diameter side by a height x2. The height x2 is set equal to or larger than the height x1 of the collar 22 of the inner ring 12 (x1 ≦ x2).

  The inner diameter of the fixing ring 27 is formed to be equal to or slightly larger than the inner diameter of the lubricating ring 26, and the fixing ring 27 suppresses axial warping when the lubricating ring 26 contacts the roller 16 during operation.

  As shown in FIG. 2, when the roller 16 is at the center position of the raceway surfaces 14, 15, the axial gap y between the end surfaces 19 of the rollers 16 and the inner surface 29 of the lubricating ring 26 and the inner ring 12. The axial gap z with the inner surface 28 of the collar 22 is set so as to satisfy the relationship y <z.

  Since the gaps y and z are in the above relationship, the position of the inner surface 28 of the collar 22 is outward by a slight amount δ (= z−y) from the position of the inner surface 29 of the lubricating ring 26. As a result, when the roller 16 moves in the axial direction (see the arrow a in FIG. 5) and its end surface 19 comes into contact with the inner side surface 29 of the lubricating ring 26, the end surface 19 and the inner side surface 28 of the collar 22 are interposed. A minute gap having a size of δ is generated.

  It should be noted that immediately after the start of operation, in order to cope with the insufficient transfer of the solid lubricant (PTFE) from the cage 17 and the lubricating ring 26, the collars of the rollers 16, the raceway surfaces 14, 15 and the inner ring 12 are preliminarily provided. By forming a solid lubricant film on the inner surface 28 of 22 by sputtering, the lubricity in the initial operation is ensured.

  FIG. 6 shows a usage example in which the cylindrical roller bearing 11 and the angular ball bearing 31 are combined. In the angular ball bearing 31, the width surface 34 of the inner ring 32 and the width surface 35 of the outer ring 33 are brought into contact with the end surfaces of the inner ring 12 and the outer ring 13 of the cylindrical roller bearing 11. Accordingly, an axial load is applied by the angular ball bearing 31, the center positions of the raceway surfaces 14 and 15 of the cylindrical roller bearing 11 are aligned, and the axial positions of the inner ring 12 and the outer ring 13 are fixed.

The cylindrical roller bearing 11 of Embodiment 1 is configured as described above. In the case of outer ring rotation, the inner ring on the fixed side has the same configuration.
Next, the operation will be described.

As described above, at the initial stage of operation, the roller 16 and the raceway surfaces 14 and 15 are lubricated by a solid lubricant film formed in advance. Further, due to the above-described minute clearance of δ, the end surface 19 of the roller 16 contacts the inner side surface 29 of the lubricating ring 26 in the initial operation, but does not contact the inner side surface 28 of the collar 22. This prevents the end surface 19 of the roller 16 from contacting the inner surface 28 of the collar 22 before transferring the solid lubricant.

  When the rolling surface 21 of the roller 16 comes into contact with the column portion 17b, the solid lubricant is transferred to the rolling surface 21. The solid lubricant transferred to the rolling surface 21 with the rotation of the rollers 16 is transferred to the raceway surfaces 14 and 15.

  The roller 16 revolves while rotating in the axial direction within the range of the left and right clearance y. When the end surface 19 of the roller 16 comes into contact with the inner surface 29 of the lubricating ring 26, transfer is performed to a contact portion in the range of the end surface 19 and the height x2.

  By setting the relationship between the height x1 of the collar 22 and the height x2 of the lubricating ring 26 such that x1 ≦ x2, the portion where the roller end surface 19 contacts the inner surface 28 can be compensated.

When the operation proceeds and the inner surface 29 of the lubricating ring 26 is worn by a thickness corresponding to δ (see FIG. 5), the solid lubricant is sufficiently transferred to the end surface 19 of the roller 16. Therefore, at that time, the end face 19 of the roller 16 and the inner side face 28 of the collar 22 are in contact with each other, and lubrication is not insufficient.
[Embodiment 2]

  The cylindrical roller bearing 11 according to the second embodiment shown in FIG. 7 has a narrow bearing width and cannot secure a sufficient width E for mounting the lubricating ring 26 and the fixing ring 27, and has a sufficient thickness for these parts. This is an effective structure as a countermeasure when it is impossible to maintain the thickness.

  That is, when the lubrication ring 26 and the fixing ring 27 are not sufficiently thick and have low rigidity, when the end face 19 of the roller 16 comes into contact with the lubrication ring 26 and an outward load is applied, the lubrication ring 26 becomes a bearing. There is a possibility of large elastic deformation to the outside. In that case, since the contact area between the end face 19 and the lubricating ring 26 is reduced, there arises a disadvantage that the solid lubricant cannot be sufficiently transferred to the end face 19 side.

  In order to prevent such inconvenience, in the case of the second embodiment, a disc spring 36 is interposed as an elastic body on the outer surface of the fixing ring 27 accommodated in the fitting groove 25 so as to support the back surface of the fixing ring 27. It is a thing.

  As shown in FIG. 8, the width between the fixing ring 27 and the inner end face of the fitting groove 25 is M, the free height of the disc spring 36 (height at no load), the end face 19 of the roller 16 and the lubricating ring. When the clearance of the inner surface 29 of 26 is F, M ≦ H, but when M <H, the relationship of HM <F is set.

  In the above proviso, if there is a relationship of M <H, the lubricating ring 26 is warped to the roller 16 side by the force of the disc spring 36. Even in this case, the lubricating ring 26 applies a load to the end face 19 of the roller 16. This means that the free height of the disc spring 36 should be set so as not to add, that is, not to contact.

  With the above configuration, an extra load is not applied to the roller 16, and the end surface 19 of the roller 16 does not warp outward when it contacts the lubricating ring 26. For this reason, even when the lubrication ring 26 and the fixing ring 27 are not sufficiently thick, as in the case of the first embodiment, the end surface 19 of the roller 16 is in the lubrication ring within the range of the height x2. 26, the solid lubricant can be transferred to the end surface 19 of the roller 16.

11 Cylindrical roller bearing 12 Inner ring 13 Outer ring 14, 15 Raceway 16 Roller 17 Cage 17a Ring portion 17b Column portion 18 Pocket 19 End surface 20 Collar 21 Rolling surface 22 Collar 23 Stepped surface 24 Mounting surface 25 Fitting groove 26 Lubricating ring 27 fixing ring 28 inner surface 29 inner surface 31 angular contact ball bearing 32 inner ring 33 outer ring 34 width surface 35 width surface 36 disc spring

Claims (13)

  An inner ring, an outer ring, a cylindrical roller interposed between these raceway surfaces, and a retainer for the roller. In the cylindrical roller bearing in which the retainer is formed of a material containing a solid lubricant, A cylindrical roller bearing characterized in that a lubricating ring containing a solid lubricant is interposed between a flange of a bearing ring.   The cylindrical roller bearing according to claim 1, wherein a fixed ring is interposed between a collar of the fixed-side raceway ring and a lubricating ring.   3. The cylindrical roller bearing according to claim 1, wherein the lubricating ring is formed of a solid lubricant or a composite material obtained by impregnating a glass lubricant with a solid lubricant.   A mounting surface that matches the width of the lubricating ring is provided on both sides of the raceway surface on the fixed side via a step surface in the diameter increasing direction, and a fitting groove for the fixing ring is provided between the mounting surface and the collar. The lubrication ring is interposed in a corner portion formed by the mounting surface and the stepped surface, and the fixing ring fitted in the fitting groove comes into contact with the lubrication ring and warps in the axial direction of the lubrication ring. The cylindrical roller bearing according to any one of claims 1 to 3, wherein the cylindrical roller bearing is suppressed.   The cylindrical roller bearing according to claim 4, wherein a width of the fitting groove is formed to match a width of the fixing ring, and the fixing ring is closely fitted to the fitting groove.   The width of the fitting groove is set to be larger than the width of the fixing ring, and an elastic body is interposed between the fixing ring fitted into the fitting groove and the collar of the fixed-side race ring. The cylindrical roller bearing according to claim 4.   The cylindrical roller bearing according to claim 6, wherein the elastic body is a disc spring.   The relationship between the height x1 of the collar of the fixed-side raceway ring and the height x2 from the raceway surface of the fixed-side raceway ring of the lubrication ring is in a relationship of x1≤x2. A cylindrical roller bearing according to any one of the above.   9. The position of the inner surface of the collar of the rotating raceway is positioned outward by a minute distance δ with respect to the position of the inner surface of the lubricating ring. Cylindrical roller bearing.   The cylindrical roller bearing according to any one of claims 1 to 9, wherein the solid lubricant is PTFE.   11. The cylindrical roller bearing according to claim 1, wherein a coating film of a solid lubricant is formed on the raceway surfaces and the rollers of the inner ring and the outer ring by sputtering.   The cylindrical roller bearing according to any one of claims 1 to 11, wherein an angular ball bearing in which the cage is formed of a material containing a solid lubricant is combined in the axial direction.   The cylindrical roller bearing according to any one of claims 1 to 12, wherein the application is a turbo pump bearing for a liquid rocket engine.

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