JP7313885B2 - thrust bearing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thrust bearing that supports an axial load of a rotating shaft, and more particularly to a thrust bearing used for a tapered land thrust bearing.

2. Description of the Related Art A tapered land thrust bearing is known which includes a thrust disk provided on a rotating shaft and a thrust bearing having a sliding surface facing the thrust disk. The sliding surface of the thrust bearing in the tapered land thrust bearing is formed of a tapered portion (inclined surface) and a land portion (thrust surface). Lubricating oil is supplied to the land portion by the wedge effect of the tapered portion, and the lubricating action with the thrust disk is enhanced.

In recent years, attempts have been actively made to form the sliding surface of a taper land thrust bearing with a synthetic resin. So far, technologies have been developed such as a thrust bearing having a sliding surface made of a resin mainly composed of Teflon (see Patent Document 1), a thrust bearing having a resin film layer formed mainly of polyamide resin, polyphenylene sulfide resin, epoxy resin, phenol resin, silicone resin, polyamideimide resin, polyimide resin, polytetrafluoroethylene resin, etc. (see Patent Document 2), and a thrust bearing having a plurality of resin sheets laminated on the thrust receiving surface (see Patent Document 3).

Japanese Patent Application Laid-Open No. 2006-183702 JP 2013-148136 A JP 2016-166662 A

However, in the conventional thrust bearing whose sliding surface is made of synthetic resin, the surface area of the tapered portion decreases due to wear of the synthetic resin sliding surface, and the surface area of the flat portion increases accordingly. Therefore, there is a problem that the rotational torque differs between when the thrust bearing is new and when it is worn and aged. In short, there was a problem that the rotational torque increased with use.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thrust bearing capable of preventing an increase in rotational torque during use.

A thrust bearing according to the present invention is a thrust bearing that receives an axial load of a rotating body, and includes a thrust surface that serves as a sliding surface on at least one bearing surface that receives the axial load, and a plurality of radial thrust surfaces that are formed at equal intervals in the circumferential direction.lubrication grooveand abovelubrication groovehas a first inclined surface whose groove depth becomes shallower in the rotational direction of the rotating body, and a second inclined surface forming a larger inclination angle than the first inclined surface with respect to the thrust surface is formed at a boundary portion between the downstream end portion of the first inclined surface in the rotational direction and the thrust surface.

A groove depth of the deepest part of the lubricating groove is ⅓ or less of the thickness of the thrust bearing.

The inclination angle of the first inclined surface with respect to the thrust surface is 3 to 30 degrees. Further, the inclination angle of the second inclined surface is 20 degrees to 60 degrees, and is 15 degrees or more with respect to the inclination angle of the first inclined surface.

The thrust surface is made of synthetic resin.

The thrust bearing is a thrust bearing that rotates relative to a thrust disk provided on a rotary shaft in a tapered land thrust bearing.

The thrust bearing of the present invention has a plurality of radial lubricating grooves formed at equal intervals in the circumferential direction on at least one bearing surface that receives an axial load. The lubricating grooves have a first inclined surface whose groove depth becomes shallower in the direction of rotation of the rotating body. Even if the sliding surface (thrust surface) of the first is worn, the surface area of the first inclined surface does not decrease, and an increase in the surface area of the sliding surface is suppressed. This can prevent an increase in rotational torque due to use.

Since the depth of the deepest part of the lubricating groove is ⅓ or less of the thickness of the thrust bearing, a sufficient thickness is ensured and the strength of the thrust bearing can be maintained.

Since the inclination angle of the first inclined surface with respect to the thrust surface is 3 to 30 degrees, it is possible to generate dynamic pressure due to lubricating oil accompanying relative rotation with other members. Further, since the inclination angle of the second inclined surface is 20 degrees to 60 degrees and is 15 degrees or more with respect to the inclination angle of the first inclined surface, it is possible to prevent the second inclined surface from suppressing the dynamic pressure.

Since the thrust surface is made of synthetic resin, the rotational torque can be reduced as compared with the case where the thrust surface is made of metal. Also, if the thrust surface is made of synthetic resin , there is a concern that the torque will increase due to wear.

INDUSTRIAL APPLICABILITY The thrust bearing of the present invention is used as a taper land thrust bearing and is a thrust bearing that rotates relative to a thrust disk provided on a rotating shaft.

It is a sectional view showing an example of a tapered land thrust bearing. 1 is a perspective view showing an example of a thrust bearing of the present invention; FIG. 3 is a plan view of the thrust bearing of FIG. 2, etc. FIG. FIG. 4 is a cross-sectional view showing another example of the thrust bearing of the present invention; It is a figure for showing the change by wear of a sliding surface.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a tapered land thrust bearing provided with the thrust bearing of the present invention. As shown in FIG. 1 , the taper land thrust bearing 1 includes a thrust disk 3 that rotates integrally with a rotating shaft 2 and a thrust bearing 4 that faces the thrust disk 3 . The thrust disk 3 is configured to be pressed against one bearing surface of the thrust bearing 4 while receiving an axial load. A thrust surface 5 of the thrust bearing 4 is a flat surface parallel to the end surface of the thrust disk 3 and constitutes a sliding surface. As the rotating shaft 2 rotates in one direction, the thrust bearing 4 rotates relative to the thrust disk 3 which is a mating sliding member.

An embodiment of the thrust bearing of the present invention will be described with reference to FIGS. 2 and 3. FIG. 2 is a perspective view of the thrust bearing, FIG. 3(a) is a front view of the thrust bearing, and FIG. 3(b) is an enlarged cross-sectional view taken along the line AA. As shown in FIG. 2, the thrust bearing 4 is an annular plate-shaped (hollow disk-shaped) member, and has a thrust surface 5 on one bearing surface that receives an axial load, and a plurality of oil grooves 6 radially extending outward in the radial direction. The oil groove 6 is formed as a recess penetrating from the inner circumference to the outer circumference of the disc on the bearing surface. During relative rotation with the thrust disk, the oil groove 6 functions as a lubricating groove, and lubricating oil is supplied to the thrust surface 5 .

As shown in FIG. 3(a), the thrust surface 5 and the oil groove 6 are alternately and repeatedly formed on the bearing surface in the circumferential direction. The plurality of oil grooves 6 are provided at regular intervals in the circumferential direction. This interval is an angular interval between lines passing through the approximate centers of the oil grooves in the circumferential direction. In FIG. 3, eight oil grooves 6 are formed, and the angular interval between adjacent oil grooves is 45°. An arrow X in FIG. 3 indicates the rotation direction of the thrust disk.

As shown in FIG. 3B, the oil groove 6 has a first inclined surface 6a whose groove depth becomes shallower in the rotation direction X. As shown in FIG. That is, the first inclined surface 6a is tapered so that the depth of the groove becomes shallower from the upstream side in the rotation direction X toward the downstream side. The angle of this taper, that is, the inclination angle α of the first inclined surface 6a with respect to the thrust surface 5 is preferably 3 to 30 degrees. If the angle is less than 3 degrees, it is difficult to form an inclined surface, and if it exceeds 30 degrees, the effect of generating dynamic pressure may be poor. The inclination angle α is more preferably 5 to 20 degrees, more preferably 5 to 15 degrees.

A second inclined surface 6b steeper than the first inclined surface 6a is provided at the boundary between the thrust surface 5 and the downstream end of the first inclined surface 6a in the rotation direction X. As shown in FIG. The inclination angle β of the second inclined surface 6b with respect to the thrust surface 5 may be larger than the inclination angle α, for example 20 to 60 degrees, preferably 35 to 60 degrees, more preferably 40 to 55 degrees. If the inclination angle β is less than 20 degrees, the area of the thrust surface 5 may change significantly when the thrust surface 5 is worn, and the desired effect may not be obtained. If the inclination angle β is steeper than 60 degrees, there is a concern that the dynamic pressure effect will be affected. In relation to the inclination angle α, the inclination angle β is preferably twice or more the inclination angle α, and preferably the inclination angle β is larger than the inclination angle α by 15 degrees or more.

A preferable form of the inclination angle α and the inclination angle β is that the inclination angle α is 5 to 20 degrees and the inclination angle β is 40 to 55 degrees. Note that FIG. 3 shows a case where the inclination angle α is 7 degrees and the inclination angle β is 45 degrees.

The ratio of the circumferential width of the first inclined surface 6a to the circumferential width of the second inclined surface 6b is preferably 5:1 to 25:1, more preferably 10:1 to 20:1. Further, in the thrust bearing of the present invention, it is preferable that all of the plurality of oil grooves are uniformly formed with the same width, the same depth, and the same groove cross-sectional shape from the inner circumference to the outer circumference of the disk.

In FIG. 3(b), the groove depth D of the oil groove 6 is preferably set in the range of 1/10 to 1/2 of the thickness T of the thrust bearing 4, more preferably in the range of 1/10 to 1/3. The groove depth D is the depth from the sliding surface (thrust surface 5) to the groove bottom, and is the depth to the deepest part when the groove bottom is an inclined surface or the like. If the groove depth D is larger than 1/2 of the thickness T, there is concern that the strength of the thrust bearing will be reduced. On the other hand, if the groove depth D is smaller than 1/10 of the thickness T, there is a concern that the dynamic pressure effect will be affected. Incidentally, the thickness T of the thrust bearing is, for example, 3 to 20 mm.

The depth D _b of the second inclined surface 6b (depth from the sliding surface at the boundary between the first inclined surface 6a and the second inclined surface 6b) is preferably 1/30 to 1/8 of the groove depth D of the oil groove 6. If the groove depth is larger than 1/8 of the groove depth D, the dynamic pressure effect may decrease, and if the groove depth is smaller than 1/30, the second inclined surface 6b may disappear when the sliding surface wears.

In FIG. 3, the first inclined surface 6a forms the groove bottom of the oil groove 6, and is directly connected to the inner wall surface of the oil groove 6, which is a surface orthogonal to the rotation direction X. As shown in FIG. This inner wall surface is positioned at the upstream end in the rotation direction X of the oil groove 6 . In FIG. 3, the deepest part of the oil groove 6 is linearly formed along the radial direction. In this case, the depth _Da of the first inclined surface 6a is the same value as the depth D of the groove.

FIG. 4 shows another example of the thrust bearing of the present invention. FIG. 4 is a cross-sectional view of the periphery of the oil groove 6' of the thrust bearing 4', corresponding to the enlarged cross-sectional view taken along line AA of FIG. As shown in FIG. 4, the oil groove 6' has a groove bottom portion 6c having a substantially rectangular cross section in addition to the first inclined surface 6a and the second inclined surface 6b. The groove bottom 6c is formed of a flat surface parallel to the thrust surface 5. As shown in FIG. The groove bottom 6c and the first inclined surface 6a are discontinuously connected via a step. With this configuration, the volume of the oil groove 6 is increased, so the retention of the lubricating oil can be enhanced. 4, the depth _Da of the first inclined surface 6a is smaller than the depth D of the groove. The shape of the groove bottom 6c may be arcuate in cross section.

As shown in FIG. 5, the thrust bearing of the present invention is provided with a second inclined surface 6b steeper than the first inclined surface 6a at the boundary between the first inclined surface 6a and the thrust surface 5 (sliding surface) (FIG. 5(a)). Therefore, even if the sliding surface wears to the same degree, the increase in the surface area of the sliding surface is small and the change in torque is suppressed compared to when the second inclined surface is not provided (FIG. 5(b)). If an inclined surface with an inclination angle smaller than that of the first inclined surface 6a is provided as the second inclined surface, the change in torque is further increased.

The material of the thrust bearing may be ferrous metal, ceramics, or synthetic resin with high rigidity. In order to reduce rotational torque, it is preferable that at least the sliding surface is made of synthetic resin. As the synthetic resin, known thermoplastic engineering plastics and thermosetting engineering plastics can be used. The thrust bearing of the present invention may be a synthetic resin molded product, a machined product, or a synthetic resin coated body. Molded products and machined products can be integrally formed with oil grooves of thrust bearings. In the case of a coated body, it is possible to manufacture a thrust bearing in which oil grooves and the like are formed using metal or ceramics as a base material, and to form a resin coating on the sliding surface.

INDUSTRIAL APPLICABILITY The thrust bearing of the present invention is applicable to taper land thrust bearings such as turbine pumps, transmissions and compressors, and can be applied to other than taper land thrust bearings.

INDUSTRIAL APPLICABILITY The thrust bearing of the present invention can be used as a low-torque thrust bearing for a long period of time because it can prevent an increase in rotational torque during use. In particular, it is suitable as a thrust bearing for a tapered land thrust bearing.

1 taper land thrust bearing 2 rotating shaft 3 thrust disk 4, 4' thrust bearing 5 thrust surface (sliding surface)
6, 6' Oil groove 6a First inclined surface 6b Second inclined surface 6c Groove bottom

Claims (5)

A thrust bearing that receives an axial load of a rotating body,
The thrust bearing has, on at least one bearing surface that receives the axial load, a thrust surface serving as a sliding surface, and a plurality of radial lubrication grooves formed at equal intervals in a circumferential direction,
the thrust surface is made of a synthetic resin,
The lubrication groove is formed penetrating from the inner circumference to the outer circumference of the ring,
The lubricating groove has a first inclined surface whose groove depth becomes shallower in the rotational direction of the rotating body, and a second inclined surface forming a larger inclination angle than the first inclined surface with respect to the thrust surface is formed at a boundary between the downstream end of the first inclined surface in the rotational direction and the thrust surface. 2. A thrust bearing according to claim 1, wherein the deepest groove depth of said lubrication groove is 1/3 or less of the thickness of said thrust bearing. 3. A thrust bearing according to claim 1, wherein the inclination angle of said first inclined surface with respect to said thrust surface is 3 to 30 degrees. 4. The thrust bearing according to any one of claims 1 to 3, wherein the second inclined surface has an inclination angle of 20 degrees to 60 degrees. 5. The thrust bearing according to any one of claims 1 to 4 , wherein said thrust bearing is a thrust bearing that rotates relative to a thrust disk provided on a rotating shaft of a tapered land thrust bearing.

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