JP2020159531A - Half-split thrust bearing for crank shaft of internal combustion engine - Google Patents

Abstract

To provide a half-split thrust bearing for a crank shaft of an internal combustion engine hardly causing fatigue in an operation.SOLUTION: According to the present invention, a semi-annular half-split thrust bearing having an Fe alloy back metal layer defining a first surface and a second surface, and a bearing alloy layer disposed on the first surface and defining a sliding face, is provided. Two thrust relieves are formed in adjacent to both end faces in a circumferential direction of the half-split thrust bearing, and each thrust relief has a thrust relief surface formed so that a wall thickness of the half-split thrust bearing is gradually thinned from the sliding face toward a circumferential end face. The thrust relief surface is composed of the bearing alloy layer, the back metal layer is formed so that a thickness thereof is gradually thinned toward the circumferential end face in the thrust relief, and the circumferential end face has a back metal end face and a bearing alloy end face. A plurality of solid lubrication members composed of at least one of MoS2, WS2, graphite and h-BN are arranged in a scattered manner on the bearing alloy end face.SELECTED DRAWING: Figure 6

Description

The present invention relates to a half-thrust bearing that receives an axial force of a crankshaft of an internal combustion engine.

In its journal portion, the crankshaft of an internal combustion engine is rotatably supported under a cylinder block of an internal combustion engine via a main bearing formed by combining a pair of half bearings in a cylindrical shape.

One or both of the pair of half-split bearings are used in combination with half-split thrust bearings that receive axial force on the crankshaft. The half-split thrust bearing is arranged on one or both of the axial end faces of the half-split bearing.

The half-thrust bearing receives an axial force generated on the crankshaft. That is, it is arranged for the purpose of bearing the axial force input to the crankshaft when the crankshaft and the transmission are connected by the clutch.

Thrust relief is formed on the sliding surface side of the half-split thrust bearing near both ends in the circumferential direction so that the thickness of the bearing member decreases toward the end face in the circumferential direction. Generally, the thrust relief is formed so that the length from the circumferential end face to the sliding surface and the depth at the circumferential end face of the half-split thrust bearing are constant regardless of the radial position. The thrust relief is formed to absorb the misalignment between the end faces of the pair of half-split thrust bearings when the half-split thrust bearing is assembled in the split bearing housing (see FIG. 10 of Patent Document 1).

The crankshaft of the internal combustion engine is supported in the journal portion of the crankshaft of the internal combustion engine via a main bearing composed of a pair of half bearings under the cylinder block of the internal combustion engine. At this time, the lubricating oil is sent from the oil gallery in the cylinder block wall through the through hole in the wall of the main bearing into the lubricating oil groove formed along the inner peripheral surface of the main bearing. The lubricating oil is thus supplied into the lubricating oil groove of the main bearing and is supplied to the latter half thrust bearing. As the thrust bearing that receives the axial force of the crankshaft of the internal combustion engine, a laminated structure in which an aluminum bearing alloy layer or a copper bearing alloy layer is formed on one surface of a back metal layer made of Fe alloy is generally used.

JP-A-11-201145

When the axial force input to the crankshaft is applied to the sliding surface of the half-split thrust bearing by connecting the crankshaft and the transmission, etc., almost at the same time, it is near the circumferential end face of the half-split thrust bearing. Since an impact force is applied to the bearing alloy layer, fatigue (cracking or peeling) may occur in the thrust relief or the bearing alloy layer on the sliding surface adjacent to the thrust relief.
More specifically, the half-split thrust bearing is used by being fitted to a receiving seat (seat surface) provided on the side surface of the cylinder block and the bearing cap, and the inner diameter of the receiving seat is the outer diameter of the half-split thrust bearing. The half-thrust bearing is slightly movable in the circumferential direction because it is formed slightly larger than the above. On the other hand, when a pair of half-split thrust bearings are used in combination in an annular shape (see, for example, FIG. 10 of Patent Document 1), the crankshaft is at the moment when the axial force from the crankshaft is input to the sliding surface of the thrust bearing. The thrust collar surface of is not in contact with both sliding surfaces of a pair of half-split thrust bearings at the same time, but tends to come into contact with the sliding surfaces of one half-split thrust bearing first. Therefore, one half-split thrust bearing moves slightly in the circumferential direction with the rotation of the thrust collar surface, and the circumferential end face on the front side of the crankshaft of one half-thrust bearing in the rotation direction is the other half-split thrust. It collides with the circumferential end faces on the rear side of the bearing crankshaft in the rotational direction, and a shocking load is applied to the vicinity of the circumferential end faces of those half-thrust bearings. Due to the impact of this shocking load, which is repeatedly applied each time the crankshaft and transmission are connected, the thrust relief adjacent to the circumferential end face of the half-split thrust bearing or the bearing alloy layer on the sliding surface adjacent to the thrust relief Fatigue (cracking and peeling from the steel backing layer) is likely to occur.

Therefore, an object of the present invention is to provide a half-thrust bearing for a crankshaft of an internal combustion engine, which is less likely to cause fatigue during operation.

In order to achieve the above object, according to the present invention
A semi-annular half-thrust bearing for receiving the axial force of the crank shaft of an internal combustion engine, which is made of an Fe alloy that defines a first surface and a second surface opposite to the first surface. It has a back metal layer and a bearing alloy layer provided on the first surface of the back metal layer, and the bearing alloy layer defines a sliding surface of a half-thrust bearing on the opposite side to the back metal layer, and is half. Two thrust reliefs were formed adjacent to both end faces in the circumferential direction of the split thrust bearing, and each thrust relief was formed so that the wall thickness of the half thrust bearing became thinner from the sliding surface toward the end face in the circumferential direction. In a half-thrust bearing with a thrust leaf surface,
The surface of the thrust relief is composed of a bearing alloy layer, and the back metal layer is formed in the thrust relief so as to become thinner toward the circumferential end face. Therefore, the peripheral end face is the back metal end face where the back metal layer is exposed and the bearing alloy. Has a bearing alloy end face with exposed layers
It further comprises a plurality of solid lubricating members interspersed on the end face of the bearing alloy, the solid lubricating member consisting of at least one of MoS ₂ , WS ₂ , graphite, and h-BN. Split thrust bearings are provided.

The area ratio (AR1) of the solid lubricating member on the end face of the bearing alloy can be 1 to 10%.

The thickness of the solid lubricating member on the end face of the bearing alloy can be 0.1 to 10 nm.

The axial length (T1) of the bearing alloy end face on the circumferential end face can be 30 to 60% of the axial length (TE) of the circumferential end face.

Solid lubricating members are arranged so as to be scattered within a range from the bearing alloy end face to a predetermined axial distance (T3) on the back metal end face, and the predetermined axial distance (T3) is set on the circumferential end face. It can be 25% to 50% of the axial length (T2) of the back metal end face.

The area ratio (AR2) of the solid lubricating member in the range from the bearing alloy end face to the predetermined axial distance (T3) on the back metal end face is 2 to 5 of the area ratio (AR1) of the solid lubricating member on the bearing alloy end face. It can be doubled (AR2 / AR1 = 1.5 to 2.5).

As described above, the half-split thrust bearing for the crankshaft receives the axial force of the crankshaft of the internal combustion engine, but according to the present invention, the bearing alloy end face of the circumferential end face of the half-split thrust bearing is solid. Since the lubricating members are provided so as to be scattered, minute slip occurs when the end face of the bearing alloy receives an impact load, and the load applied to the bearing alloy layer is alleviated.
Therefore, it is difficult for the impact load to propagate to the bearing alloy layer in the region of the thrust relief surface or the region of the sliding surface adjacent to the thrust relief, and therefore fatigue is unlikely to occur in the bearing alloy layer in these regions.

It is an exploded perspective view of a bearing device. It is a front view of the bearing device. It is sectional drawing of the bearing device. It is a front view of the half-thrust bearing of Example 1. FIG. It is sectional drawing parallel to the axial direction of the circumferential end portion of the half-split thrust bearing of Example 1. FIG. It is an enlarged side view of the peripheral end portion shown in FIG. It is a front view of a half bearing. It is a bottom view which looked at the half bearing shown in FIG. 7 from the inside in the radial direction. It is a front view of the half-thrust bearing of Example 3. FIG. It is a side view of the peripheral end portion of the half-split thrust bearing of Example 3. FIG. It is a side view of the peripheral end portion of the half-split thrust bearing of Example 4. FIG. It is a front view of the end face in the circumferential direction of the half-split thrust bearing of Example 1. FIG. FIG. 5 is an enlarged side view of the circumferential end surface of the half-split thrust bearing of the first embodiment as viewed from the direction of the ZI arrow in FIG. FIG. 5 is an enlarged front view of the circumferential end surface of the half-split thrust bearing of the first embodiment as viewed from the direction of arrow ZII in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Overall configuration of bearing device)
First, the overall configuration of the bearing device 1 according to the first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 to 3, the bearing housing 4 formed by attaching the bearing cap 3 to the lower portion of the cylinder block 2 is formed with bearing holes (holding holes) 5 which are circular holes penetrating between both side surfaces. The bearing holes 6 and 6 which are annular recesses are formed on the peripheral edge of the bearing hole 5 on the side surface. Half-split bearings 7 and 7 that rotatably support the journal portion 11 of the crankshaft are combined and fitted in the bearing hole 5 in a cylindrical shape. Half-split thrust bearings 8 and 8 that receive an axial force f (see FIG. 3) via a thrust collar 12 of a crankshaft are combined and fitted to the receiving seats 6 and 6 in an annular shape.

As shown in FIG. 2, of the half-split bearings 7 constituting the main bearing, a lubricating oil groove 71 is formed on the inner peripheral surface of the half-split bearing 7 on the cylinder block 2 side (upper side), and the lubricating oil groove 71 is also formed. A through hole 72 penetrating the outer peripheral surface is formed inside (see also FIGS. 7 and 8). The lubricating oil groove can also be formed in both the upper and lower half bearings.

Further, the half-split bearing 7 is formed with crash reliefs 73 and 73 at both ends in the circumferential direction adjacent to the contact surface between the half-split bearings 7 (see FIG. 2). The crush relief 73 is a wall thickness reduction region formed so that the wall thickness of the region adjacent to the circumferential end face of the half bearing 7 gradually becomes thinner toward the circumferential end face. The crash relief 73 is formed by planning to absorb the misalignment and deformation of the butt surface when the pair of half bearings 7 and 7 are assembled.

(Composition of half-thrust bearing)
Next, the configuration of the half-split thrust bearing 8 of the first embodiment will be described with reference to FIGS. 2 to 6. The half-split thrust bearing 8 of this embodiment is formed in a semi-annular flat plate using a bimetal in which a thin bearing alloy layer 85 is bonded to a back metal layer 84 made of Fe alloy. As the Fe alloy of the back metal layer 84, steel, stainless steel, or the like can be used. Further, as the bearing alloy layer 85, a Cu bearing alloy, an Al bearing alloy, or the like can be used. The bearing alloy layer 85 has a lower hardness (softer) than the back metal layer 84 made of Fe alloy, and therefore has a large amount of elastic deformation when subjected to an external force.
The half-split thrust bearing 8 has a sliding surface 81 (bearing surface) composed of a bearing alloy layer 85 in the central region in the circumferential direction, and thrust reliefs 82 and 82 in regions adjacent to both end surfaces 83 and 83 in the circumferential direction. However, the thrust relief 82 has a flat thrust relief surface (flat surface) 82s. Two oil grooves 81a and 81a are formed on the sliding surface 81 between the thrust reliefs 82 and 82 on both sides in order to improve the oil retention property of the lubricating oil.

The thrust relief 82 is formed in a region on the sliding surface 81 side adjacent to both end faces 83 and 83 in the circumferential direction so that the wall thickness T of the half-split thrust bearing 8 gradually becomes thinner toward the end face. It is a region and extends over the entire radial direction of the circumferential end face 83 of the half-split thrust bearing 8. The thrust relief 82 is misaligned between the circumferential end faces 83, 83 of the pair of half-thrust bearings 8, 8 due to misalignment when the half-split thrust bearing 8 is assembled in the split type bearing housing 4. Is formed to alleviate.

As shown in FIG. 4, the thrust relief 82 of the present embodiment has a constant thrust leaf length L1 between the radial inner end portion and the radial outer end portion of the half-split thrust bearing 8.
When used for the crankshaft of a small internal combustion engine for passenger cars (the diameter of the journal portion is about 30 to 100 mm), the thrust relief length L1 from the circumferential end face 83 of the half-split thrust bearing 8 is set to 3 to 25 mm. Ru.

Here, the thrust relief length L1 is defined as a length measured in the vertical direction from a plane (thrust bearing division plane HP) passing through both end faces 83 in the circumferential direction of the half-split thrust bearing 8. In particular, the thrust relief length L1 at the radial inner end is defined as the vertical length from the circumferential end surface 83 of the half-split thrust bearing 8 to the point where the thrust leaf surface 82s intersects the inner peripheral edge of the sliding surface 81. Defined.

Further, the thrust leaf 82 of the half-split thrust bearing 8 has a constant axial depth RD1 between the radial inner end portion and the radial outer end portion of the half-split thrust bearing 8 on the circumferential end surface 83. It is formed.
The axial depth RD1 of the thrust relief 82 can be 0.1 to 1 mm.

Here, the axial depth means the axial distance from the plane including the sliding surface 81 of the half-split thrust bearing 8 to the thrust relief surface 82s. In other words, the axial depth is the distance measured vertically from the virtual sliding surface extending the sliding surface 81 onto the thrust relief 82 to the thrust relief surface 82s. Therefore, the axial depth RD1 is specifically defined as the depth from the thrust relief surface 82s to the virtual sliding surface on the circumferential end surface 83 of the half-split thrust bearing 8.

As shown in FIG. 5, the back metal layer 84 defines two surfaces, that is, a first surface 84a to which the bearing alloy layer 85 is adhered and a second surface 84b forming the back surface of the half-thrust bearing 8. are doing.

From the viewpoint of actual production, the shape of the thrust relief surface 82s may be a slightly curved curve with a circumferential cross section perpendicular to the sliding surface 81, and similarly, the back metal layer 84 of the thrust relief 82. The shape of the first surface 84a may be a slightly curved curve with a circumferential cross section perpendicular to the sliding surface 81.

The bearing alloy layer 85 covers the first surface 84a of the back metal layer 84 and extends to the peripheral end surface 83 so that the thrust relief surface 82s is composed of the bearing alloy layer 85. Therefore, as shown in FIGS. 5 and 6, the circumferential end surface 83 of the half-split thrust bearing 8 has a bearing alloy end surface 86 in which the bearing alloy layer 85 is exposed and a back metal end surface 87 in which the back metal layer 84 is exposed.

FIG. 12 is a view of the circumferential end surface 83 (that is, the bearing alloy end surface 86 and the back metal end surface 87) viewed from the front surface (ZII arrow direction in FIG. 6). Further, FIG. 13A is an enlarged view of the circumferential end surface 83 viewed from the side, that is, from the thrust relief surface 82s side (ZI arrow viewing direction in FIG. 6), and FIG. 13B shows the bearing alloy end surface 86 in front of the thrust relief surface 86. It is an enlarged view seen from the ZII arrow view direction of FIG. In particular, as shown in FIGS. 13A and 13B, the bearing alloy end face 86 is provided so that a plurality of solid lubricating members 88 are scattered, and therefore, the bearing alloy end face 86 is provided with a portion where the bearing alloy layer 85 is exposed and a solid. It is understood that the lubricating member 88 is mixed (FIG. 13B). The solid lubricating member 88 is composed of at least one of MoS ₂ , WS ₂ , graphite, and h-BN, and the area ratio of the entire solid lubricating member 88 to the surface area of the bearing alloy end face 86 is 1 to 10%. Is.

In the first embodiment, the thickness T4 of the solid lubricating member 88, that is, the vertical height T4 from the bearing alloy end face 86 is 0.1 to 10 nm.
If the thickness T4 of the solid lubricating member 88 is less than 0.1 nm, the action of alleviating the impact load applied to the bearing alloy 85 when an impact load is applied is insufficient, but if the thickness T4 exceeds 10 nm. When the solid lubricating member 88 is subjected to an impact load, the solid lubricating member 88 may be cracked or easily sheared from the bearing alloy end face 86.

Further, in the first embodiment, the axial length T1 of the bearing alloy end face 86 in the circumferential end face 83 is 30 to 60% with respect to the axial length (thickness) TE of the circumferential end face 83. The reason is that when the axial length T1 of the bearing alloy end face 86 in the circumferential end face 83 exceeds 60% with respect to the axial length TE of the circumferential end face 83, the ratio of the back metal end face 87 in the circumferential end face 83. Is too small, and the back metal layer 87 near the peripheral end face 83 may be plastically deformed.

In FIG. 6, the connection portion between the thrust relief surface 82s and the bearing alloy end surface 86 and the connection portion between the first surface 84a of the back metal layer 84 and the back metal end surface 87 in the thrust relief 82 are formed linearly (that is,). Although they form corners), these connections may be curved (ie, rounded).

(Action according to Example 1)
As described above, almost at the same time that the axial force f from the crankshaft is input to the sliding surface 81 of the half-split thrust bearing 8, the circumferential end surface 83 of one half-thrust bearing 8 and the other half-thrust bearing 8 are input. The circumferential end faces 83 of 8 collide with each other, whereby a shocking load is applied to the vicinity of the circumferential end faces 83 of the half-split thrust bearings 8. In addition, unlike the configuration of this embodiment, of the bearing housing 4 configured by attaching the bearing cap 3 to the lower part of the cylinder block 2 shown in FIG. 1, the annular shape of the peripheral edge of the bearing hole 5 is provided only on the side surface of the cylinder block 2. When a recess 6 is formed and therefore only one half-thrust bearing is arranged on one side of the bearing housing 4, the circumferential end face 83 of the half-thrust bearing 8 is the bearing cap 3. It collides with the end face (split surface), and as a result, a shocking load is applied to the vicinity of the circumferential end face 83 of the half-split thrust bearing 8.

In this embodiment, since the solid lubricating members 88 are provided so as to be scattered on the bearing alloy end face 86 of the circumferential end face 83 of the half-split thrust bearing, the bearing alloy end face 86 slips slightly when an impact load is applied. Is generated, and the load applied to the bearing alloy layer 85 is alleviated. Therefore, it is difficult for the impact load to propagate to the bearing alloy layer 85 in the region of the thrust relief surface 82s and the region of the sliding surface 81 adjacent to the thrust relief 82, and therefore fatigue is unlikely to occur in the bearing alloy layer 85 in these regions. ..

Further, in the present invention, since the solid lubricating members 88 are scattered on the bearing alloy end face 86, when an impact load is applied to the circumferential end face 83 of the thrust bearing 8, each solid lubricating member is placed in the bearing alloy end face 86. Since it is pushed in and surrounded by the bearing alloy and restrained, the solid lubricating member 88 is unlikely to be deformed in the direction parallel to the bearing alloy end face 86, and the solid lubricating member 88 is unlikely to be sheared from the bearing alloy end face 86.
On the other hand, unlike the present invention, when the solid lubricating member is provided on the entire surface of the end face 86 of the bearing alloy, the solid lubricating member is greatly deformed and the solid lubricating member is cracked because the above-mentioned bearing alloy does not have a peripheral restraining action. It is generated and easily sheared from the bearing alloy end face 86.
Alternatively, if the particles of the solid lubricating member are embedded so as to be flush with the end face 86 of the bearing alloy, the bearing alloy of the half-split thrust bearing 8 is formed from the solid lubricating member 88 by the heat generated when the internal combustion engine is operated. Since a large amount of thermal expansion occurs, the surface of the solid lubricating member is recessed with respect to the bearing alloy end face 86, and the same operation as that of the present invention cannot be obtained.

Unlike this embodiment, if the area ratio of the solid lubricating member 88 on the bearing alloy end face 86 is less than 1%, a minute slip occurs when an impact load is applied, and the action of alleviating the impact load is ineffective. On the other hand, if the area ratio exceeds 30%, the solid lubricating member 88 may be easily sheared from the bearing alloy end face 86.

(Dimensions of bearing alloy layer and back metal layer)
FIG. 5 is a cross-sectional view of a side surface of the half-split thrust bearing 8 as viewed from the inside (YI arrow direction in FIG. 4) in the vicinity of the circumferential end 83.
When used for the crankshaft of a small internal combustion engine for passenger cars (the diameter of the journal portion is about 30 to 100 mm), the thickness T of the half-split thrust bearing 8 is 1.5 in the region where the sliding surface 81 is formed. The thickness of the back metal layer 84 is 1.1 to 3.2 mm, and the thickness TA of the bearing alloy layer 85 is 0.1 mm to 0.7 mm. In the region where the sliding surface 81 is formed, the thickness TB of the back metal layer 84 and the thickness TA of the bearing alloy layer 85 are preferably constant.
Further, as shown in FIGS. 5 and 6, in the region where the thrust relief 82 is formed, the thickness of the bearing alloy layer 85 and the back metal layer 84 decreases from the central side in the circumferential direction toward the end surface 83 in the circumferential direction. The axial length (thickness) T2 of the bearing alloy end face 86 on the circumferential end face 83 is preferably 0.05 to 0.6 mm.

(Material of bearing alloy layer)
As the bearing alloy, conventionally known Cu bearing alloys and Al bearing alloys can be used. For example, the Cu bearing alloy may be a Cu alloy containing one or more components selected from Sn, P, Ni, Zn, Fe, Ag, Bi, and Pb. The Al bearing alloy may be an Al alloy containing at least one component selected from Si, Sn, Cu, Fe, Cr, Mg, Mn, Zr, Ti, and V. The Cu bearing alloy and the Al bearing alloy may contain components other than those shown above.

(Material of back metal layer)
For the back metal layer, an Fe alloy containing 0.03 to 0.35% by mass of carbon can be used.
Further, the composition of the back metal layer is 0.03 to 0.35% by mass of C, 0.4% by mass or less of Si, 1% by mass or less of Mn, 0.04% by mass or less of P, 0.05% by mass. It is preferable that the following S is contained and the balance is Fe and unavoidable impurities.
The composition of the back metal layer is not limited to the above composition, and may be another Fe alloy.

(Measurement of area ratio of solid lubrication member)
The area ratio of the solid lubricating member 88 in the bearing alloy end face 86 of the circumferential end face 83 of the half-split thrust bearing 8 is a plurality of places (for example, 3 places) of the bearing alloy end face 86 at a magnification of 5000 times using EPMA (electron microanalyzer). The above) can be confirmed by performing a quantitative analysis of the components. Elements constituting the solid lubricating member (for example, Mo element and S element in the case of MoS ₂ ) and component elements contained in the bearing alloy (for example, Al element and Si element in the case of Al bearing alloy) as detection elements in the quantitative analysis. , Sn element, etc.), and after converting the characteristic X-ray intensity of these elements into mass concentration by the ZAF correction calculation method, it is converted into volume concentration. The total volume concentration of the elements constituting the solid lubricating member at each measurement point is the volume concentration of the solid lubricating member, and the value of this volume concentration at each measurement point is arithmetically averaged to determine the area ratio of the solid lubricating member 88. Can be confirmed. When the bearing alloy has a composition containing the same element as the solid lubricating member, the volume concentration of the same element as the solid lubricating member contained in the bearing alloy is excluded from the value of the volume concentration of the element of the solid lubricating member. The value is the area ratio of the solid lubricating member 88. This quantitative analysis is not limited to 5000 times, and may be performed at a magnification exceeding 5000 times, for example.
The area ratio of the solid lubricating member 88 on the back metal end surface 87 adjacent to the bearing alloy end surface 86 of the circumferential end surface 83 of the half-split thrust bearing 8 described later can also be measured by the same method.

(Coating method of solid lubricating member)
As a coating method for the solid lubricating member, it is possible to coat the bearing alloy end face 86 with the solid lubricating member 88 by using a general projection method or the like. A solid lubricant is coated by using a general projection method in which the solid lubricant particles of the solid lubricant member 88 are heated to room temperature or a temperature at which the solid lubricant does not decompose and then collide with the peripheral end face 86 by the force of a compressed gas to cover the solid lubricant. By adjusting conditions such as particle size, projection speed, projection time, and compressed gas pressure, the bearing alloy end face 86 of the circumferential end face 83 of the half-split thrust bearing 8 or the bearing alloy end face 86 and the back metal end face 87 adjacent thereto A predetermined area can also be coated with the solid lubricant so as to be scattered.

In this embodiment, the bearing device 1 of the type in which the half-split bearing 7 and the half-split thrust bearing 8 are separated has been described, but the present invention is not limited to this, and the half-split bearing 7 and the half-split thrust are not limited to this. It can also be applied to a bearing device 1 of a type in which a bearing 8 is integrated. Further, the half-split thrust bearing 8 may cover the sliding surface 81 of the bearing alloy layer 85, the thrust relief surface 82s and / or the second surface 84b of the back metal layer 84 so that the solid lubricating members are scattered. it can.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes to the extent that the gist of the present invention is not deviated from the present invention. Included in the invention.

In the half-thrust bearing 8 of the second embodiment, the solid lubricating members are formed so as to be scattered in the region 89 of the back metal end face 87 adjacent to the bearing alloy end face 86, and the other configurations are the same as those of the first embodiment. Is.
Specifically, in this embodiment, in addition to the bearing alloy end face 86, the solid lubricating member 88 is scattered in the range 89 of the back metal end face 87 from the bearing alloy end face 86 to the predetermined axial distance T3. The axial distance T3 is 25% to 50% of the axial length T2 of the back metal end surface 87 in the circumferential end surface (FIG. 12).
By forming the solid lubricating member 88 on the thrust relief surface 82s side of the back metal end surface 87 of the back metal layer 84, minute slip occurs, and the impact load is alleviated also in the region 89 of the back metal end surface 87 adjacent to the bearing alloy end surface 86. To.
On the other hand, on the back side of the back metal end surface 87 of the back metal layer 84 (the side opposite to the thrust relief surface 82s), only the back metal end surface 87 is exposed, so that the impact load is mainly from the bearing alloy layer 85 of the back metal end surface 87. Join a distant area. Therefore, it is difficult for the impact load to propagate to the bearing alloy layer 85 in the region of the thrust relief surface 82s and the region of the sliding surface 81 adjacent to the thrust relief 82, and therefore fatigue is unlikely to occur in the bearing alloy layer 85 in these regions. ..
Further, the surface of the back metal layer 84 (back metal end surface 87) has a higher frictional force when it comes into impact contact with the mating member than the surface of the bearing alloy layer 85 (bearing alloy end surface 86). Therefore, the area ratio of the solid lubricating member 88 within the range 89 from the bearing alloy end face to the predetermined axial distance T3 on the back metal end face 87 so that minute slip is likely to occur when an impact load is applied. AR2) is preferably 1.5 to 2.5 times (AR2 / AR1 = 2 to 5) the area ratio (AR1) of the solid lubricating member 88 on the bearing alloy end face 86.
The area ratio of the solid lubricating member 88 on the back metal end surface 87 within the range 89 from the bearing alloy end surface to the predetermined axial distance T3 is less than 1.5 times the area ratio of the solid lubricating member 88 on the bearing alloy end surface 86. In some cases, it may be difficult to sufficiently obtain the effect of alleviating the impact load on the back metal end surface 87, and if it exceeds 2.5 times, the solid lubricating member 88 may be easily sheared from the back metal end surface 87.

For example, as shown in FIGS. 9 and 10, the present invention can also be applied to a half-thrust bearing 8'with a protruding portion 8p protruding outward in the radial direction for positioning and rotation stop. Further, the circumferential length of the half-split thrust bearing 8'may be shorter than the half-split thrust bearing 8 shown in the first embodiment by a predetermined length S1. Further, the half-split thrust bearing 8'can also have an inner peripheral surface cut out in the vicinity of the peripheral end portion 83 in an arc shape having a radius R. Similarly, chamfers may be formed in the radial outer edge portion and the radial inner edge portion on the sliding surface side of the half-split thrust bearing 8'over the circumferential direction.

As shown in FIG. 11, the half-split thrust bearing 8 ″ according to the fourth embodiment also has thrust relief on both ends in the circumferential direction of the back surface (second surface 84b of the back metal layer 84) opposite to the sliding surface 81. It can have a back relief 90 with a similar shape. In this case, the thickness of the back metal layer 84 is defined as the thickness measured from the second surface 84b when the back surface relief 90 is not formed.
Alternatively, the back relief 90 may be configured to have a plane parallel to the sliding surface 81.
As shown in FIG. 11, the relief length L3 of the back relief 90 is larger than the thrust relief length L1 of the above-mentioned thrust relief 82, but is not limited to this, and is the same as the thrust relief length L1. It may be present, or it may be smaller than the thrust relief length L1.

Further, in the first embodiment, four half-split thrust bearings 8 are used in the bearing device 1, but the present invention is not limited to this, and at least one half-split thrust bearing 8 according to the present invention is used. This makes it possible to obtain the desired effect. Further, a ring-shaped thrust bearing composed of a half-split thrust bearing 8 according to the present invention and a conventional thrust bearing as a pair may be used. Further, in the bearing device 1 of the present invention, the half-split thrust bearing 8 may be integrally formed on one or both end faces in the axial direction of the half-split bearing 7 that rotatably supports the crankshaft.

L1 Thrust relief length at the inner end in the radial direction RD1 Depth of thrust leaf at the end face in the circumferential direction 1 Bearing device 4 Bearing housing 7 Half bearing 8 Half thrust bearing 11 Journal part 12 Thrust collar 71 Lubricating oil groove 72 Through hole 73 Crash Relief 81 Sliding surface 82 Thrust relief 82s Thrust relief surface 83 Circumferential end face 84 Back metal layer 84a First surface 84b Second surface 85 Bearing alloy layer 86 Bearing alloy end face 87 Back metal end face 88 Solid lubricating member 89 Predetermined back metal end face Range 90 back relief

Claims (6)

A semi-annular half-thrust bearing for receiving axial force of the crank shaft of an internal combustion engine, which is an Fe alloy that defines a first surface and a second surface opposite to the first surface. The back metal layer is provided with a bearing alloy layer provided on the first surface of the back metal layer, and the bearing alloy layer is a sliding surface of the half-thrust bearing on the opposite side to the back metal layer. Two thrust reliefs are formed adjacent to both end faces in the circumferential direction of the half-split thrust bearing, and each thrust relief is formed from the sliding surface toward the end face in the circumferential direction of the half-split thrust bearing. In a half-thrust bearing having a thrust relief surface formed so that the wall thickness is thin,
The surface of the thrust leaf is made of the bearing alloy layer, and the back metal layer is formed in the thrust leaf so as to become thinner toward the peripheral end face, so that the back metal layer is exposed on the peripheral end face. It has a back metal end face and a bearing alloy end face from which the bearing alloy layer is exposed.
It further has a plurality of solid lubricating members arranged so as to be scattered on the end face of the bearing alloy, and the solid lubricating member comprises at least one of MoS ₂ , WS ₂ , graphite, and h-BN. Half-split thrust bearing. The half-thrust bearing according to claim 1, wherein the area ratio (AR1) of the solid lubricating member on the end face of the bearing alloy is 1 to 10%. The half-thrust bearing according to claim 1 or 2, wherein the solid lubricating member on the end face of the bearing alloy has a thickness of 0.1 to 10 nm. Any one of claims 1 to 3, wherein the axial length (T1) of the bearing alloy end face on the circumferential end face is 30 to 60% of the axial length (TE) of the circumferential end face. Half-split thrust bearing described in. The solid lubricating members are arranged so as to be scattered within a range from the bearing alloy end face to a predetermined axial distance (T3) on the back metal end face, and the predetermined axial distance (T3) is the circumference. The half-split thrust bearing according to any one of claims 1 to 4, which is 25% to 50% of the axial length (T2) of the back metal end face in the direction end face. The area ratio (AR2) of the fixed lubricating member within the range from the bearing alloy end face to the predetermined axial distance (T3) on the back metal end face is the area ratio of the solid lubricating member on the bearing alloy end face (T3). The half-split thrust bearing according to claim 5, which is 1.5 to 2.5 times that of A1).