JP2013148136A - Thrust sliding bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust sliding bearing capable of increasing oil film pressure even at low rotational speed and capable of suppressing occurrence of wear or an increase in frictional resistance.SOLUTION: In a thrust sliding bearing 1 for supporting the axial load of a rotary shaft 4, the bearing surface 1a of a thrust bearing plate 2 is divided into a plurality of fan-shaped thrust pad surfaces 7 by radially formed oil supply grooves 6. In each thrust pad surface 7, a U-shaped first projection 11 is formed along the circumferential edge of the pad surface, the projection having a predetermined width and a given predetermined height (6 μm) and opening toward the oil supply groove 6; and a second projection 12 having a height (5.5 μm) lower than the above predetermined height is formed in the rear part of a region enclosed by the first projection 11.

Description

  The present invention relates to a thrust slide bearing that supports an axial load of a rotating shaft.

  A thrust plain bearing is generally composed of a bearing base having an annular bearing surface, or a bearing base and an annular thrust bearing plate mounted on the bearing base, and is transmitted from a thrust collar of a rotating shaft arranged oppositely. The axial load is supported by the bearing surface of the bearing member (bearing base or thrust bearing plate). In fluid lubricated bearings that use lubricating oil, in order to ensure the reliable supply of lubricating oil to the bearing surface and increase the load capacity by improving the oil film pressure, radial oil supply grooves are formed to form a plurality of fan-shaped bearing surfaces. Many of these are divided into thrust pad surfaces.

  To improve the oil film pressure, lubricate by forming a thrust pad surface so that the oil film thickness is large on the front side (lubricating oil inlet side) and the oil film thickness is small on the rear side (lubricating oil outlet side). It is necessary to exert a wedge effect on the oil. As such a thrust slide bearing, there is a taper land bearing having a tapered wedge shape (for example, Patent Document 1). Further, the land surface having the smallest oil film thickness in the taper land bearing is formed in a U-shape extending to a predetermined width along the peripheral edge of the thrust pad surface and opening toward the front oil supply groove. A thrust slide bearing in which the inside of the surface is a tapered surface inclined in a direction in which the oil film thickness on the front side increases is known (Patent Document 2).

Japanese Examined Patent Publication No. 62-12305 JP-A-6-288411

  The wedge action has such a characteristic that it becomes smaller as the ratio (B / L) of the width B of the thrust pad surface to the circumferential length L becomes smaller. However, as in Patent Document 2, the land surface has a U-shape. With this configuration, it is expected that the wedge effect is effectively worked without increasing B / L, that is, without increasing the outer diameter of the thrust pad surface.

  However, if a tapered surface is formed on the thrust pad surface as in the prior art, it is difficult to taper a minute dimension, so the height of the tapered surface (depth from the land surface) increases. Therefore, when a bearing is applied to support a rotating shaft or the like for an automobile engine whose rotation speed changes frequently, the oil film pressure increases according to the rotation speed in the high-speed rotation range, so there is no problem of wear or friction resistance. However, since the oil film pressure does not increase in the relatively low speed normal rotation region, the oil film thickness on the outlet side tends to be thin. When the thrust load is increased and mixed lubrication is performed, wear occurs and a boundary frictional force is added in addition to the shearing force of the lubricating oil, resulting in an increase in frictional resistance.

Here, the wedge shape is made into a step shape that can be easily machined into minute dimensions, and the step is set to a relatively small size so that the oil film pressure becomes high in the normal rotation range, thereby enabling mixed lubrication during engine operation. It is possible to prevent it. However, when the engine rotates at a low speed such as at the start (when it is equal to or less than the idling speed), the oil film pressure decreases and the oil film thickness at the pad outlet decreases. The performance factor K of the wedge effect is determined by the ratio (h ₁ / h ₂ ) between the oil film thickness h ₁ (maximum oil film thickness) at the inlet and the oil film thickness h ₂ (minimum oil film thickness) at the outlet. becomes maximum at 2.2, since it has a characteristic to decrease this ratio is too large, the oil film thickness h ₂ at the outlet becomes smaller, so that also decreases the wedge effect at the same time. Therefore, oil film thickness h _2, and the oil film pressure at the outlet as the rotation speed is at low speed suddenly decreases, the frictional resistance increases with wear occurs during low-speed rotation such as when starting up and stopping.

  The present invention has been devised to solve the problems included in the prior art, and a thrust slide that can increase the oil film pressure even during low-speed rotation and suppress the occurrence of wear and increase in frictional resistance. An object is to provide a bearing.

  In order to solve such a problem, according to one aspect of the present invention, there is provided a thrust slide bearing (1, 21) for supporting an axial load of the rotating shaft (4), and the thrust bearing member (2) The thrust receiving surface (1a, 21a) is divided into a plurality of fan-shaped thrust pad surfaces (7) by radially formed oil supply grooves (6), and the thrust pad surface has a predetermined width along the periphery. And it is set as the structure in which the U-shaped 1st convex part (11) which protrudes to a fixed predetermined height and opens toward the oil supply groove | channel of the front side was formed.

  According to this configuration, it is possible to configure a step bearing in which the first convex portion forms a flat surface, and by configuring the first convex portion to be small, the oil film pressure is increased even during low-speed rotation, and the friction is increased. Increase in resistance and wear can be suppressed.

  According to another aspect of the present invention, the thrust pad surface is provided with a second convex portion (12) lower than the predetermined height in a rear portion of a region surrounded by the first convex portion. Can be configured.

  According to this configuration, the oil film pressure during rotation at a lower speed can be increased, and an increase in frictional resistance and wear can be more effectively suppressed.

  Moreover, according to one aspect of the present invention, the first convex portion and the second convex portion can be configured by a resin coating layer. Thereby, a convex part can be formed easily.

  Moreover, according to one aspect of the present invention, the first convex portion and the second convex portion can be made of metal plating. Thereby, a convex part with high abrasion resistance can be formed.

  Further, according to one aspect of the present invention, the thrust receiving surface of the thrust bearing member is formed with a machined streak (3a), and the first convex part and the second convex part are on the streak. It can be set as the formed structure.

  According to this structure, the adhesive force of the convex part with respect to a thrust bearing surface can be improved. In addition, even if the protrusions are worn, the molecules of the protrusions remain in the valleys of the streaks, and the oil film thickness can be reduced by the average thickness of the streaks, that is, the protrusions remain. Since the same state can be achieved, the effect can be maintained when the convex portion is formed of a material that easily wears or when the eccentric amount of the rotating shaft is large.

  As described above, according to the present invention, it is possible to provide a thrust slide bearing capable of increasing the buoyancy and securing an oil film having a sufficient thickness.

Front view of thrust sliding bearing according to the embodiment Sectional view along the line II-II in FIG. Front view of a thrust plain bearing according to a modified embodiment Sectional view along line IV-IV in FIG. The graph which shows the relationship between the rotation speed and oil film thickness in the bearing which concerns on embodiment Conceptual diagram showing a change in state of the convex portion shown in FIG.

  Hereinafter, an embodiment of a thrust slide bearing (hereinafter simply referred to as a bearing) 1 according to the present invention will be described in detail with reference to the drawings. 2 and 4, the vertical dimension of the paper surface is exaggerated.

  As shown in FIGS. 1 and 2, the bearing 1 has an annular plate shape and is made of a metal thrust bearing plate 2 having a flat surface, and a metal provided on the surface of the thrust bearing plate 2. The first coating layer 3 is provided as a main component. The bearing 1 is disposed such that the front surface (hereinafter referred to as a bearing surface 1a) on the first coating layer 3 side is opposed to the thrust collar 5 of the rotating shaft 4, and the axial load transmitted from the thrust collar 5 is a bearing surface. Support with la. The thrust collar 5 is integrated with the rotary shaft 4 and rotates clockwise in FIG. 1 as indicated by an arrow.

  On the first coating layer 3, a streak 3 a (see FIG. 6) is formed by machining. The streak 3a may be formed by boring, or may be formed by microgroove finishing by pressing or the like.

  Eight oil supply grooves 6 extending radially at equal angular intervals are formed in the bearing 1, and the bearing surface 1 a is divided into eight fan-shaped thrust pad surfaces 7. The oil supply groove 6 is formed to a depth that opens to the bearing surface 1a and reaches the thrust bearing plate 2, and supplies lubricating oil to the thrust pad surface 7 on the rear side, that is, on the downstream side in the rotational direction.

  In each thrust pad surface 7, a U-shaped second coating layer 8 that protrudes along the periphery to a predetermined width and a constant predetermined height and opens toward the front oil supply groove 6 is a surface of the first coating layer 3. Is formed. The second coating layer 8 is an arc-shaped inner portion extending in the circumferential direction along the radially inner edge, an arc-shaped outer portion extending in the circumferential direction along the radially outer edge, and a lubricant outlet. It is comprised from the linear rear-end part extended in radial direction along an edge. Here, the width of the inner part and the outer part are both 1.5 mm, the width of the rear end part (peripheral length at the center position in the radial direction) is 6 mm, and the inner part, the outer part and the rear end part are Both heights are set to 5.5 μm.

  Further, on each thrust pad surface 7, a U-shaped third coating layer 9 that protrudes along the periphery to a predetermined width and a constant predetermined height and opens toward the front oil supply groove 6 is a second coating layer 8. Is formed on the surface. The third coating layer 9 is an arc-shaped inner portion extending in the circumferential direction along the radially inner edge, an arc-shaped outer portion extending in the circumferential direction along the radially outer edge, and the lubricant coating outlet. It is comprised from the linear rear-end part extended in radial direction along an edge. Here, both the width of the inner portion and the outer portion is 1.5 mm, which is the same as that of the second coating layer 8, and the width of the rear end portion (circumferential length at the center position in the radial direction) is 2 mm. Both the outer portion and the rear end have a height of 0.5 μm. In addition, the thickness of the 3rd coating layer 9 is thinner than the thickness of the 2nd coating layer 8, and 1 micrometer or less is preferable.

  That is, in the second coating layer 8, only the front side 4 mm portion of the rear end portion is exposed to form the bearing surface 1 a, and the other portions are covered by the third coating layer 9. In other words, the thrust pad surface 7 is formed with a U-shaped first convex portion 11 that protrudes to a height of 6 μm along the periphery by the third coating layer 9 and opens toward the front oil supply groove 6. At the same time, a second convex portion 12 protruding to a height of 5.5 μm is formed in the rear portion of the region surrounded by the first convex portion 11. In addition, as for the width | variety of the inner side part and the outer side part of the 1st convex part 11, 1 mm-2 mm are preferable.

  The second coating layer 8 and the third coating layer 9 can be formed as a resin coating layer made of a single resin having bottom friction resistance and high heat resistance. Or you may form as a resin film layer which consists of composite resin which contains a solid lubricant in single synthetic resin. The resin coating layer is formed, for example, by degreasing, washing, and preheating the first coating layer 3, applying a coating material that becomes a resin coating layer to the surface by spray coating or screen printing, and curing the coating material at a high temperature. The

  Examples of the resin that is the main material of the second coating layer 8 and the third coating layer 9 include polyamide resin (PA), polyphenylene sulfide (PPS), epoxy resin, phenol resin, silicone resin, polyamideimide resin (PAI), and polyimide resin. (PI), polytetrafluoroethylene (PTFE), or the like can be used. Two or more composite resins selected from these resins may be used. The “composite resin” includes a resin blend, a polymer alloy, and a copolymerization.

On the other hand, as solid lubricants, inorganic solid lubricants such as transition metal sulfides such as molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS ₂ ), graphite, hexagonal boron nitride, synthetic mica, and talc filler. And fillers made of fluorine-based resins such as polytetrafluoroethylene (PTFE) and tetrafluoroethylene perfluoroalkyl vinyl ether (PFA). These may be used alone or in combination of two or more.

  Alternatively, the second coating layer 8 and the third coating layer 9 may be formed of a metal plating layer. As the main material of the metal plating layer, soft metals such as tin, copper, silver, and alloys thereof can be used. The metal plating layer can be formed, for example, by plating or vapor deposition.

  According to the bearing 1 configured as described above, the buoyancy can be increased and an oil film having a sufficient thickness can be secured. That is, the flat first protrusion 11 constitutes the first step D1 in the step bearing, and the height of the first step D1 is set to a small value of 6 μm, so that the oil film pressure is high even at low speed rotation. Thus, an increase in frictional resistance and wear is suppressed. And the 2nd convex part 12 which makes a plane constitutes the 2nd level difference D2 in a step bearing, and the height of the 2nd level difference D2 is 0.5 micrometer which is 1/2 or less of the 1st level difference D1. By setting it to a small value, the oil film pressure during rotation at a lower speed becomes higher, and the increase in frictional resistance and wear is more effectively suppressed.

<Modified Embodiment>
Next, a bearing 21 according to a modified embodiment will be described with reference to FIGS. 3 and 4. In addition, the same code | symbol is attached | subjected to the member and site | part similar to embodiment, and the description about the structure and effect is abbreviate | omitted.

  The bearing 21 according to the modified embodiment includes the thrust bearing plate 2 and the first coating layer 3 as main components as in the above embodiment. On the other hand, in each thrust pad surface 7, only the second coating layer 28 is formed on the surface (bearing surface 21 a) of the first coating layer 3. In the second coating layer 28, the width of the inner part and the outer part are both 1.5 mm, the width of the rear end part (the circumferential length at the center position in the radial direction) is 6 mm, Both the outer portion and the rear end are 6 μm in height. In other words, only the first U-shaped convex portion 11 that protrudes to the height of 6 μm along the peripheral edge and opens toward the front oil supply groove 6 is formed on the thrust pad surface 7 by the second coating layer 28. ing.

  Even if the bearing 21 is configured in this way, the first convex portion 11 forming a flat surface constitutes the first step D1 of the step bearing, and the height of the first step D1 is set to a small value of 6 μm. As a result, the oil film pressure increases even during low-speed rotation, and the increase in frictional resistance and wear is suppressed.

<Effect>
Next, the effects of the embodiment and the modified embodiment will be described in more detail with reference to FIG. FIG. 5 is a graph in which the horizontal axis represents the rotation speed of the rotary shaft 4 and the vertical axis represents the oil film thickness at the outlet, and (B) shows an enlarged view of a portion B in (A). In the graph, the solid line indicates the two-step bearing 1 according to the above-described embodiment, the one-point difference line indicates the one-step bearing 21 according to the above-described modified embodiment, and the broken line indicates the first configuration with the same configuration as in the above-described modified embodiment. A conventional one-step step bearing in which a step is formed as small as possible by machining so that the oil film pressure is increased only in the height of the convex portion 11 in the normal rotation region is shown.

  As shown in the drawing, in the conventional one-step bearing, the oil film thickness at the pad outlet is small during low speed rotation such as at the time of starting. On the other hand, in the one-step bearing 21 according to the modified embodiment, the oil film thickness at the outlet is larger than that of the conventional one-step bearing. Further, in the two-step bearing 1 according to the embodiment, the oil film thickness at the outlet is larger in the lower speed rotation region than the one-step bearing 21 according to the modified embodiment.

  As described above, as the oil film thickness at the outlet decreases, the wedge effect also decreases, but in the present invention, since the oil film thickness at the outlet can be increased, the oil film thickness rapidly decreases in the low speed rotation region. It can be seen that the increase in frictional resistance and wear can be suppressed.

  And in the said embodiment, as shown in the upper left of FIG. 6, the streak 3a is formed in the surface of the 1st coating layer 3, and the 2nd coating layer 8 (the 1st convex part 11, the 2nd convex part 12) is formed. Since it forms on the stripe 3a, the adhesive force with respect to the 1st coating layer 3 of the 2nd coating layer 8 is high. Further, as shown in the lower left of FIG. 6, even if the second and third coating layers 8 and 9 are worn, the molecules of the second coating layer 8 remain in the valleys of the stripes 3a, thereby causing the stripes 3a. Thus, the oil film thickness is reduced by the average thickness of the second coating layer 8 as shown in the lower right of FIG. The effect is maintained even when the coating layers 8 and 9 are formed or when the thrust load of the rotating shaft 4 is large.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above embodiment, the bearing 1 supports the thrust collar 5 of the rotating shaft 4, but the bearing is provided integrally with the rotating shaft so as to face the bearing wall, and between the thrust receiving surface of the bearing wall. An axial load may be supported. Moreover, in the said embodiment, although the bearing 1 is made into the annular plate shape, it is good also as a fan-shaped semicircular disk shape. In addition, the specific configuration, arrangement, and quantity of each member and part can be changed as long as they do not depart from the spirit of the present invention. On the other hand, all the components of the bearing 1 according to the present invention shown in the above embodiment are not necessarily essential, and can be appropriately selected as long as they do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1,21 Bearing 1a, 21a Bearing surface 2 Thrust bearing plate 3 1st coating layer 3a Streak 4 Rotating shaft 6 Oil supply groove 7 Thrust pad surface 8, 28 2nd coating layer 9 3rd coating layer 11 1st convex part 12 1st 2 convex parts

Claims (5)

  A thrust slide bearing for supporting an axial load of a rotating shaft, wherein a thrust receiving surface of a thrust bearing member is divided into a plurality of sector-shaped thrust pad surfaces by radially formed oil supply grooves, and the thrust pad surface The thrust sliding bearing is characterized in that a U-shaped first convex portion is formed that protrudes along the periphery to a predetermined width and a predetermined height and opens toward the front oil supply groove.   2. The thrust according to claim 1, wherein a second convex portion lower than the predetermined height is formed on a rear side portion of a region surrounded by the first convex portion on the thrust pad surface. Slide bearing.   The thrust sliding bearing according to claim 1 or 2, wherein the first convex portion and the second convex portion are made of a resin coating layer.   The thrust sliding bearing according to claim 1 or 2, wherein the first convex portion and the second convex portion are made of metal plating.   The thrust bearing surface of the thrust bearing member is formed with a machined streak, and the first convex part and the second convex part are formed on the streak. Item 5. The thrust slide bearing according to any one of Items 4 to 4.

Images