JP2012247026A - Cylindrical roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical roller bearing without a risk of insufficient lubrication between a cylindrical roller and a flange surface of a bearing ring.SOLUTION: The cylindrical roller bearing 10 comprises: a flangeless inner ring 12 having a raceway surface 12a on the outer circumference, a flangeless outer ring 14 having a raceway surface 14a on the inner circumference, a plurality of cylindrical rollers 16 interposed between the raceway surface 12a of the inner ring 12 and the raceway surface 14a of the outer ring 14, and a retainer 18 having pockets 18a, for housing respective cylindrical rollers 16, disposed in the circumferential direction, and the axial movement of the cylindrical rollers 16 is restricted by interference of the retainer, the inner ring, and the outer ring. As the bearing rings 12, 14 each has no flange, contact itself between a roller end surface 16b and the flanges is eliminated, and a problem of insufficient lubrication at contact portions is dissolved.

Description

  The present invention relates to a cylindrical roller bearing used in, for example, a cryogenic fluid, and can be used as an example for a bearing used in liquid oxygen or liquid hydrogen of a turbo pump for a rocket engine, that is, a cryogenic propellant.

  At present, the mainstream of bearings used in turbo pumps for rocket engines is angular ball bearings (see Non-Patent Document 1), and in many cases, two angular ball bearings are used in combination as shown in FIG. FIG. 13 shows a turbo pump for a rocket engine, which compresses liquid oxygen of a liquid hydrogen / liquid oxygen two-stage combustion rocket engine. Although not shown, the liquid hydrogen / liquid oxygen two-stage combustion rocket engine also includes a similar turbo pump for compressing liquid hydrogen.

  The angular ball bearing 52 used for the turbine shaft 44 reaches a maximum rotation of about 18000 rpm. In addition, the angular ball bearing of the turbo pump which compresses liquid hydrogen becomes about 52000 rpm at maximum.

  Further, since liquid oxygen flows into the turbo pump, these angular ball bearings 52 are exposed to a cryogenic environment of -183 ° C. In the case of an angular ball bearing of a turbo pump that compresses liquid hydrogen, the temperature is −253 ° C. For this reason, the angular ball bearing used for the rocket engine turbo pump is required to operate under severe conditions such as high-speed rotation and a cryogenic environment.

  As described above, since the use environment of the bearing is in the cryogenic propellant (˜−253 ° C.), it is impossible to supply the lubricant from the outside. Therefore, the lubrication is performed by the solid lubricant film treatment (PTFE sputtering treatment) on the raceway surface, guide surface and rolling element of the bearing and the transition film of the solid lubricant component (PTFE) from the cage (Patent Documents 1 and 2). reference).

Japanese Patent Publication No. 2-20854 JP 2002-147462 A

Masataka Nosaka, Masataka Kikuchi, Mamoru Oike, "Cryogenic and self-lubricating high-speed ball bearings for rocket turbo pumps", Turbomachinery, Nippon Kogyo Publishing Co., Ltd., March 1996, Vol. 24, No. 3, p. 28-34 Japan Bearing Industry Association, “Rolling Bearing Terms”, Japanese Standards Association, July 20, 1993, p. 110-111

  In order to improve the performance and reliability of a rocket engine turbo pump, it is said that it is necessary to increase the rigidity around the rotating shaft. Along with this, it is necessary to increase the rigidity of the bearing, but it is difficult to significantly increase the rigidity with the current ball bearing. Therefore, it is desired to use a cylindrical roller bearing having a large radial load capacity and high rigidity because the raceway ring and the cylindrical roller are in line contact. However, there are the following problems in order to use the cylindrical roller bearing in a cryogenic environment. That is, in the case of a cylindrical roller bearing, the lubricant transfer from the cage occurs between the guide surface of the bearing ring and the rolling element, that is, the rolling surface of the cylindrical roller. In addition to the raceway surface, there is a collar surface as the part where the cylindrical roller and the raceway contact, but since the inner wall surface of the cage pocket and the end surface are not always in plane contact, the lubricant transfer to the roller end surface Therefore, sufficient lubricant transfer cannot be expected. Therefore, there is a concern about insufficient lubrication between the roller end face and the collar face. The collar is defined as a narrow portion protruding from the surface of the raceway and parallel to the rolling direction, and is intended to hold and guide the roller in the bearing (Non-Patent Document 2).

  An object of the present invention is to provide a cylindrical roller bearing which does not have to worry about insufficient lubrication between the cylindrical roller and the collar surface of the race.

The present invention solves the problem by making the raceway a collar. By making the raceway without a collar, there is no contact between the roller end face and the collar face itself, so that the problem of insufficient lubrication between the roller end face and the collar face cannot occur. Along with the elimination of the collar, the axial movement of the cylindrical roller is restricted by the interference between the cage and the race. That is, the cylindrical roller bearing of the present invention, an inner ring having a raceway surface on the outer periphery, an outer ring having a raceway surface on the inner periphery, a plurality of cylindrical rollers interposed between the raceway surface of the inner ring and the raceway surface of the outer ring, In a cylindrical roller bearing comprising a cage in which pockets for accommodating the respective cylindrical rollers are arranged in the circumferential direction, the inner ring and the outer ring have no collar, and the axial movement of the cylindrical roller is controlled by the cage, the inner ring, and the outer ring. It is characterized by being restricted by interference with the outer ring.
Specific means for interference between the cage and the inner ring and the outer ring include, for example, a cage, a radially inward flange that contacts the inner ring when the cage moves in one of the axial directions, and vice versa. A radially outward flange is provided that contacts the outer ring when moved in the direction. Alternatively, the inner ring is provided with a radially outward flange that interferes with the cage when the cage moves in one of the axial directions, and the radially inward flange that interferes with the cage when the cage moves in the opposite direction. You may employ | adopt the structure provided in.

  According to the present invention, since the race is made without a collar, the problem of insufficient lubrication between the cylindrical roller and the collar surface of the race is solved. Therefore, the cylindrical roller bearing according to the present invention can be used in an extremely low temperature and non-lubricated state, and since it has a higher radial rigidity than an angular ball bearing, it has an increased rigidity required as a bearing for a turbo pump for a rocket engine. Can meet the demand.

It is a longitudinal section showing an embodiment of this invention. It is the elements on larger scale of FIG. It is sectional drawing similar to FIG. It is IV arrow line view of FIG. FIG. 4 is a view taken in the direction of arrow V in FIG. 3. It is a longitudinal cross-sectional view which shows another embodiment. It is VII-VII sectional drawing of FIG. It is VIII-VIII sectional drawing of FIG. It is the elements on larger scale of FIG. FIG. 10 is a cutaway perspective view of the outer ring in FIG. 9. 6 is a schematic cross-sectional view showing a modified example of Example 1. FIG. It is a longitudinal cross-sectional view which shows the prior art. FIG. 6 is a longitudinal sectional view of a liquid oxygen turbopump for a rocket engine showing a conventional technique.

  First, Example 1 will be described with reference to FIGS. FIG. 1 shows a cylindrical roller bearing 10 according to the first embodiment. The broken line indicates the angular contact ball bearing 50 for positioning, which will be described later. As shown in FIG. 1, the cylindrical roller bearing 10 includes an inner ring 12, an outer ring 14, a plurality of cylindrical rollers 16, and a cage 18.

  As can be seen from FIG. 2 showing the enlarged main part of FIG. 1, the inner ring 12 has no collar, has a raceway surface 12a at the center of the outer peripheral surface, and a tapered portion 12b is formed on one side of the raceway surface 12a. In addition, a small diameter portion 12d is formed on the small diameter side of the tapered portion 12b. The side wall of the small diameter portion 12d is an annular end surface 12c perpendicular to the axis. The tapered portion 12b is for facilitating the assembly of the cylindrical roller bearing 10. That is, the inner ring 12 can be assembled without interfering with the end face of the cylindrical roller 16 by inserting the inner ring 12 from the tapered portion 12b inside the cylindrical roller row arranged on the inner circumference of the outer ring 14. .

  Without the outer ring 14, it has a raceway surface 14 a at the center of the inner peripheral surface, and a large-diameter portion 14 c is formed at the axial end opposite to the small-diameter portion 12 d of the inner ring 12. The side wall of the large diameter portion 14c is an annular end surface 14b perpendicular to the axis.

  The cylindrical roller 16 is interposed between the raceway surface 12a of the inner ring 12 and the raceway surface 14a of the outer ring 14, and rolls on the raceway surfaces 12a and 14a on the cylindrical outer peripheral surface, ie, the rolling surface 16a, when the bearing rotates. What is indicated by reference numeral 16b is a roller end face.

The cage 18 has a pocket 18 a for accommodating each cylindrical roller 16. The pockets 18a are disposed at predetermined intervals in the circumferential direction of the cage 18, and each pocket 18a penetrates the cage 18 in the radial direction. Of the inner wall surface of the pocket 18a, the inner wall surface portion facing the cage axial direction, that is, the end surface 16b faces the gaps A ₁ and A ₂ in the axial direction.

A radially inward flange 18 b is formed at one end of the cage 18. The inner diameter of the inward flange 18 b is slightly larger than the small diameter portion 12 d of the inner ring 12. The inner surface of the inward flange 18b and the annular end surface 12c of the inner ring 12 face each other in the axial direction with an axial clearance B therebetween.
A radially outward flange 18 c is formed at the other end of the cage 18. The outer diameter of the outward flange 18 c is slightly smaller than the large diameter portion 14 c of the outer ring 14. The inner side surface of the outward flange 18c and the annular end surface 14b of the outer ring 14 face each other in the axial direction with an axial clearance C therebetween.

Axial clearances A ₁ and A ₂ between the roller end face 16 b and the cage 18, an axial clearance B between the inner ring 12 and the cage 18, and an axial clearance C between the outer ring 14 and the cage 18. By managing, the axial movement amount of the cylindrical roller 16 can be regulated. Here, the allowable axial movement amount of the cylindrical roller 16 is represented by A ₁ + A ₂ + B + C. For example, the allowable axial movement amount of the cylindrical roller 16 is set by adjusting the axial clearance B between the inner ring 12 and the cage 18 and the axial clearance C between the outer ring 14 and the cage 18. be able to.

  As shown in FIGS. 3 to 5, a through hole or a notch may be provided in the outer ring 14 and the retainer 18 so that the cryogenic propellant can easily pass through the bearing in the axial direction. The shape of the through hole or the notch is not limited, but it is preferable to arrange at equal intervals at two or more locations on the circumference in terms of rotational balance. FIG. 4 shows an example of a through hole / notch provided in the cage 18, and shows four types of a circular through hole 19a, an oval through hole 19b, a semicircular notch 19c, and a rectangular notch 19d. FIG. 5 shows an example of notches provided in the outer ring 14 and shows an example in which segment-like notches 19e are provided at eight positions at equal intervals in the circumferential direction.

  Referring again to FIG. 1, there is shown an example in which a positioning angular ball bearing 50 is used in combination with the cylindrical roller bearing 10 described above. That is, in the cylindrical roller bearing 10 of FIG. 1, when the cage 18 tries to move in one axial direction (right side in FIG. 1), it interferes with the inner ring 12 and tries to move in the opposite direction (left side in FIG. 1). Interferes with the outer ring 14. Thus, the axial movement of the cage 18 and thus also the cylindrical roller 16 is restricted by the interference between the cage 18 and the race rings 12 and 14. However, if the inner ring 12 or the outer ring 14 moves in the axial direction, regulation due to interference between the cage and the raceway ring is not effective. Therefore, the inner ring 12 and the outer ring 14 are positioned using the angular ball bearing 50. Since the angular ball bearing 50 has a thrust load capability, it is disposed in contact with the cylindrical roller bearing 10 as shown in the figure, thereby preventing the positioning of the cylindrical roller bearing 10, that is, the axial movement of the inner ring 12 and the outer ring 14. Fulfill. Thus, since the angular ball bearing 50 is exclusively for positioning, an existing one can be adopted. Therefore, the detailed description is abbreviate | omitted.

  As materials for the inner ring 12, the outer ring 14, and the cylindrical roller 16, martensitic stainless steel (JISG4303 SUS440C) is adopted because rolling fatigue strength and wear resistance are required simultaneously with corrosion resistance. A solid lubricating coating is applied to the raceway surface 12 a and the annular end surface 12 c of the inner ring 12, the raceway surface 14 a and the annular end surface 14 b of the outer ring 14, and the rolling surface 16 a of the cylindrical roller 16. A typical example of such a solid lubricating coating is PTFE.

  The material constituting the cage 18 is preferably a material having self-lubricating properties for the purpose of adhesion of the transfer film to the cylindrical roller 16. In addition to forming the entire cage 18 with a self-lubricating material, a layer or coating made of a self-lubricating material may be provided on the surface of a metal base material. Such a layer or coating is provided on the entire surface of the cage 18 including the inner wall surface of the pocket 18a. Here too, PTFE can be mentioned as a representative example of the self-lubricating material.

  By not providing a collar on the raceway ring, that is, the inner ring 12 and the outer ring 14, there is no portion in contact with the roller end surface 16b during operation, so that the problem of insufficient lubrication at the contact portion with the roller end surface 16b is eliminated. Although the roller end surface 16b of the cylindrical roller 16 and the inner wall surface of the pocket 18a of the cage 18 are in contact with each other, at least the surface layer of the cage 18 is formed of a self-lubricating material. It is rather advantageous for lubrication because the transition and transfer of the resin are promoted.

  Next, Example 2 will be described with reference to FIGS. Since the second embodiment is the same as the first embodiment regarding the axial movement amount restriction of the cylindrical roller, the material, the solid lubricating coating treatment, and the like, the repeated description is omitted. As shown in FIGS. 6 and 7, the cylindrical roller bearing 20 includes an inner ring 22, an outer ring 24, a plurality of cylindrical rollers 26, and a cage 28. These components are the same as those in the first embodiment. However, in the cylindrical roller bearing 10 of the first embodiment, the inner ring 12, the outer ring 14, the rollers 16, and the cage 18 are all separated, whereas the cylinder of the second embodiment. In the roller bearing 20, the outer ring 24, 26, and the cage 28 are not separated.

  As shown in FIG. 8, the inner ring 22 has no collar, has a raceway surface 22a at the center portion of the outer peripheral surface, a tapered portion 22b is formed on one side of the raceway surface 22a, and a smaller diameter side of the tapered portion 22b. Is formed with a small diameter portion 22d. The side wall of the small diameter portion 22d is an annular end surface 22c perpendicular to the axis. The cylindrical roller 26 is interposed between the raceway surface 22a of the inner ring 22 and the raceway surface 24a of the outer ring 24, and rolls on the raceway surfaces 22a and 24a on the cylindrical outer peripheral surface, that is, the rolling surface 26a when the bearing rotates. Reference numeral 26b denotes a roller end face.

The outer ring 24 has a raceway surface 24a at the center of the inner peripheral surface, and a large diameter part 24c is formed at the axial end of the inner ring 22 opposite to the small diameter part 22d. The side wall of the large diameter portion 24c is an annular end surface 24b perpendicular to the axis.
The outer ring 24 has roller retaining portions 24d and 24e on both sides of the raceway surface 24a. The roller retaining portions 24d and 24e are annular projections having a smaller diameter than the raceway surface 24a, and play a role of preventing the cylindrical roller 26 from moving out in the axial direction.

  The cage 28 has a pocket 28a for accommodating each cylindrical roller 26 (see FIG. 7). The pockets 28a are arranged at predetermined intervals in the circumferential direction of the cage 28, and each pocket 28a penetrates the cage 28 in the radial direction. Of the inner wall surface of the pocket 28a, the inner wall surface portion facing the cage axial direction, that is, the end surface 26b faces the gaps H and J in the axial direction (see FIG. 9).

  Further, the cage 28 has a pair of roller drop prevention portions 28d for each pocket 28a (see FIG. 7). As shown in FIG. 8, the roller stopper 28d is located at the center in the cage width direction, and from the side of the column 27 between the adjacent pockets 28a, in other words, the cage circumference of the pocket 28a. It protrudes toward the center side of the pocket 28a from the inner wall surface portion facing in the direction. The distance between the pair of roller drop-preventing portions 28d facing each other across the pocket 28a is smaller than the diameter of the cylindrical roller 26. Therefore, the roller fall-preventing portion 28d serves to prevent the cylindrical roller 26 from falling to the inner diameter side of the cage.

  In this case, when assembling the cylindrical roller bearing 20, the cage 28 is disposed inside the outer ring 24, and the cylindrical roller 26 is inserted into the pocket 28 a of the cage 28 from the inside of the cage 28. At this time, the cylindrical roller 26 is pushed radially outward of the retainer 28 using the elastic deformation of the roller stopper 28d (snap-in). By providing the roller retaining portions 24d and 24e, and the retaining portions 28d, these three members can be handled as one non-separable unit after the outer ring 24, the cylindrical roller 26 and the cage 28 are once assembled. . Thereafter, the assembly of the cylindrical roller bearing 20 is completed by inserting the inner ring 22 inside the row of cylindrical rollers 26.

It is preferable to set the dimensional relationship in the axial direction as follows so that the cylindrical roller 26 does not come into contact with the roller retaining portions 24d and 24e even if the cylindrical roller 26 moves in the axial direction (see FIG. 9).
D> G + J and E> F + H
here,
D: distance between cylindrical roller 26 and retaining portion 24d;
E: distance between the cylindrical roller 26 and the retaining portion 24e;
F: Clearance between the cage 28 and the annular end surface 22c of the inner ring 22;
G: Clearance between the cage 28 and the annular end surface 24b of the outer ring 24,
H, J: Clearances between the roller end face 26b and the inner wall surface of the pocket 28a.

  The roller retaining portions 24d and 24e are similar in shape to the “rib”, but are not in contact with the cylindrical roller 26 as long as the above conditions are satisfied. is there. This is why the word “brim” is not used in the names of the roller retaining portions 24d and 24e.

  In Example 2, the bearing internal flow path of the cryogenic propellant is hindered by the roller retaining portions 24d and 24e of the outer ring 24, so that the roller retaining portions 24d and 24e are penetrated as shown in FIGS. Holes 24f and 24g are provided to form a flow path that allows the cryogenic propellant to pass through. The through hole 24f passes through the roller retaining portion 24d in the outer ring axial direction. It is desirable to arrange the plurality of through holes 24f at equal intervals in the circumferential direction. Further, the through hole 24g penetrates the roller retaining portion 24e in the outer ring axial direction. It is desirable to arrange the plurality of through holes 24g at equal intervals in the circumferential direction. Furthermore, the through-hole 24f and the through-hole 24g have the same phase as shown in the figure, and can also have different phases. However, at least partially aligned (overlapping) allows the propellant to pass with less resistance. be able to.

As described in the first embodiment with reference to FIG. 4, the retainer 28 in the second embodiment may also be provided with through holes 19a and 19b or notches 19c and 19d.
As a modification of the first embodiment, a flange may be provided on the inner ring and the outer ring instead of providing the cage with a flange. That is, as shown in FIG. 11, the cage 38 for holding the roller 36 is a straight cylinder. A radially outward flange 40 is provided at one axial end of the inner ring 32. The outer ring 34 is provided with a radially inward flange 42 at the axial end of the inner ring 32 opposite to the outward flange 40. When the cage 38 moves toward one side in the axial direction, for example, the left side in FIG. 11, the cage 38 and the outward flange 40 of the inner ring 32 interfere with each other. When the retainer 38 is moved toward the right side in FIG. 11, the retainer 38 and the inward flange 42 of the outer ring 34 interfere with each other. In this way, the axial movement of the cage is restricted.

  As described above, the embodiment has been described taking the case of application to a bearing used in a rocket engine turbo pump as an example. However, the present invention can also be applied to a cylindrical roller bearing used in other cryogenic environments. The effect can be expected.

10, 20, 30 Cylindrical roller bearing 12, 22, 32 Inner ring 12a, 22a Raceway surface 12b, 22b Tapered part 12c, 22c Annular end face 12d, 22d Small diameter part 14, 24, 34 Outer ring 14a, 24a Raceway surface 14b, 24b Annular end face 14c, 24c Large diameter part 24d, 24e Roller retaining part 24f, 24g Hole 16, 26, 36 Cylindrical roller 16a, 26a Rolling surface 16b, 26b Roller end face 18, 28, 38 Cage 18a, 28a Inside pocket 18b, 28b Orientation flange 18c, 28c Outward flange 28d Roll stopper 40 Outward flange 42 Inward flange

Claims (15)

  An inner ring having a raceway surface on the outer periphery, an outer ring having a raceway surface on the inner periphery, a plurality of cylindrical rollers interposed between the raceway surface of the inner ring and the raceway surface of the outer ring, and a pocket for housing each cylindrical roller. In a cylindrical roller bearing comprising a cage disposed in a direction, the inner ring and the outer ring are without a collar, and axial movement of the cylindrical roller is regulated by interference between the cage, the inner ring and the outer ring. A cylindrical roller bearing characterized by the above.   The cylindrical roller bearing according to claim 1, wherein the cage has an inward flange that contacts the inner ring when moved in the axial direction, and an outward flange that contacts the outer ring when moved in a direction opposite to the axial direction. .   A small-diameter portion is provided on the outer periphery of the end portion of the inner ring, a side wall of the small-diameter portion is formed as an annular end surface facing the inward flange in the axial direction, and a large-diameter portion is provided on the inner periphery of the end portion of the outer ring. The cylindrical roller bearing according to claim 1 or 2, wherein the side wall of the portion is an annular end face facing the outward flange in the axial direction.   By adjusting the clearance between the annular end surface of the inner ring and the inward flange of the cage, and the clearance between the annular end surface of the outer ring and the outward flange of the cage, the allowable shaft of the cylindrical roller is adjusted. The cylindrical roller bearing according to claim 3, wherein the amount of directional movement is set.   5. The cylindrical roller bearing according to claim 1, wherein the cylindrical roller bearing is used in combination with an angular ball bearing for positioning in order to regulate an axial relative positional relationship between the inner ring and the outer ring.   2. The outer ring, the cylindrical roller, and the cage are combined into a single unit by providing a roller retaining portion on the outer ring and a roller drop preventing portion on the cage. The cylindrical roller bearing according to any one of 4.   The cylindrical roller bearing according to claim 6, wherein the roller retaining portions are annular projections located on both sides of the raceway surface of the outer ring and having a smaller diameter than the raceway surface.   The roller drop prevention part protrudes from the side surface of the pillar of the retainer toward the center of the pocket, and the separation distance between the roller drop prevention parts facing each other across the pocket is smaller than the diameter of the cylindrical roller. Cylindrical roller bearing.   The cylindrical roller bearing according to any one of claims 1 to 8, wherein at least a surface layer of the cage is made of a material having self-lubricating properties.   The cylindrical roller bearing according to claim 9, wherein a base material of the cage is made of metal.   The cylindrical roller bearing according to any one of claims 1 to 10, wherein a solid lubricating treatment coating is applied to the inner ring, the outer ring, the rolling surfaces of the cylindrical rollers, and the raceway axial movement restriction end surfaces.   The cylindrical roller bearing according to claim 9, 10 or 11, wherein the self-lubricating material is PTFE.   The cylindrical roller bearing according to any one of claims 1 to 12, wherein the retainer is provided with a through hole or a notch that allows passage of the cryogenic fluid.   The cylindrical roller bearing according to any one of claims 1 to 13, wherein the outer ring is provided with a through hole or a notch that allows passage of the cryogenic fluid. The cylindrical roller bearing according to any one of claims 1 to 14, wherein the cryogenic fluid is liquid oxygen or liquid hydrogen, and is used for a turbo pump for a rocket engine.

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