JP2018112281A - Half-split thrust bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a half-split thrust bearing for receiving axial line direction force of a crank shaft of an internal combustion engine that is difficult to generate damage (fatigue) during operation of the internal combustion engine.SOLUTION: The present invention relates to a semi-annular half-split thrust bearing. The half-split thrust bearing has a slide face for receiving axial line direction force, and a back face at a side opposite to the slide face, and defines a reference face vertical to an axial line direction at a back face side. The slide face comprises two flat planes with a circumferential center part of the half-split thrust bearing as a border. An axial line direction distance from the reference face to the slide face is maximum at the circumferential center part at any radial position of the half-split thrust bearing, and becomes smaller toward both circumferential ends. Only one equal thickness part whose axial line direction distance is constant between a radial inside end and a radial outside end of the half-split thrust bearing at a position where a circumferential angle is 40°-50° from each circumferential direction end to the circumferential center part.SELECTED DRAWING: Figure 2

Description

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

  The crankshaft of the internal combustion engine is rotatably supported at the lower part of the cylinder block of the internal combustion engine via a main bearing configured by combining a pair of half bearings in a cylindrical shape at a journal portion thereof.

  One or both of the pair of half bearings are used in combination with a half thrust bearing that receives the axial force of the crankshaft. The half thrust bearing is disposed on one or both of axial end faces of the half bearing.

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

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

Conventionally, in consideration of bending deformation of the crankshaft during operation of the internal combustion engine, a curved crowning surface is provided on at least the outer diameter side of the sliding surface of the half thrust bearing, thereby sliding the half thrust bearing. It has also been proposed to reduce local contact stress between the surface and the crankshaft (Patent Document 2).
Furthermore, an inclined surface (thrust) extending from the circumferential end of the half thrust bearing to approximately half the height of the top (the outer diameter end at the center in the circumferential direction of the half thrust bearing) on the sliding surface of the half thrust bearing. It has also been proposed to form a relief and thereby reduce the inclination angle of the inclined surface with respect to the sliding surface (see Patent Document 3).

JP-A-11-2011145 JP 2013-19517 A JP 2013-238277 A

  In recent years, the shaft diameter of the crankshaft has been reduced in order to reduce the weight of the internal combustion engine, and the rigidity has become lower than that of the conventional crankshaft. The vibration tends to increase. For this reason, the thrust collar surface of the crankshaft is in sliding contact with the sliding surface of the half thrust bearing while inclining, and the inclination direction changes as the crankshaft rotates. Therefore, the sliding surfaces near both ends in the circumferential direction of the half thrust bearing are in direct contact with the thrust collar surface of the crankshaft, and damage (fatigue) is likely to occur.

  In addition, when a pair of half thrust bearings are assembled at each axial end of the main bearing consisting of a pair of half bearings, the end surfaces of the pair of half thrust bearings when assembled in the split bearing housing If the position is shifted, the gap between the sliding surface of one half thrust bearing and the thrust collar surface of the crankshaft is larger than the gap between the other half thrust bearing and the thrust collar surface of the crankshaft. Also grows. Alternatively, when only one half thrust bearing is assembled at each axial end of the main bearing, there is a large gap between the side surface of the split bearing housing where the half thrust bearing is not disposed and the thrust collar surface of the crankshaft. A gap is formed. When the internal combustion engine is operated in a state where such a gap is formed and the crankshaft is bent, the thrust collar surface of the crankshaft is further inclined toward the formed gap.

  When the crankshaft rotates with such a large inclination toward the gap, the inclination of the thrust collar surface with respect to the sliding surface of the half thrust bearing in the plane including both circumferential end surfaces of the half thrust bearing becomes larger. . Further, the inclination of the thrust collar surface is within the plane including both circumferential end surfaces of the half thrust bearing. (A) A sliding surface near the circumferential end of the half thrust bearing on the rear side in the rotational direction of the crankshaft. And the thrust collar surface are in contact with each other and the sliding surface near the circumferential end on the front side in the rotational direction of the crankshaft is separated from the thrust collar surface, and (b) rotation of the crankshaft of the half thrust bearing The sliding surface near the circumferential end on the front side in the direction and the thrust collar surface are in contact with each other, and the sliding surface near the circumferential end on the rear side in the rotation direction of the crankshaft is separated from the thrust collar surface. Is repeated as the crankshaft rotates. Since the half thrust bearing is always in direct contact with the thrust collar surface of the crankshaft, only the sliding surfaces near both ends in the circumferential direction are likely to be damaged (fatigue).

  When the inclination of the thrust collar surface to the gap side due to the bending of the crankshaft is large, and therefore the inclination of the thrust collar surface in the plane including both circumferential end faces of the half thrust bearing is large, Patent Document 2 and Patent Document Even when the technique described in No. 3 is employed, it is difficult to prevent only the sliding surfaces near the circumferential end portions of the half thrust bearing from always contacting the thrust collar surface of the crankshaft.

  Accordingly, an object of the present invention is to provide a half thrust bearing that is less susceptible to damage (fatigue) during operation of an internal combustion engine.

In order to achieve the above object, according to one aspect of the present invention, there is provided a semi-annular half thrust bearing for receiving an axial force of a crankshaft of an internal combustion engine, for receiving the axial force. And a half thrust bearing having a back surface opposite to the sliding surface and defining a reference surface perpendicular to the axial direction on the back surface side,
The sliding surface is composed of two planes with the center in the circumferential direction of the half thrust bearing as a boundary,
The axial distance from the reference surface to the sliding surface is the maximum at the center in the circumferential direction of the half thrust bearing at any radial position of the half thrust bearing, and toward the both ends of the half thrust bearing in the circumferential direction. Is getting smaller,
The axial distance is constant between the radially inner end and the radially outer end of the half thrust bearing at a circumferential angle of 40 ° to 50 ° from each circumferential end surface toward the circumferential central portion. Only one iso-thick part is formed,
In the region of the half thrust bearing on the circumferential end side from this equal thickness portion, the axial distance is maximum at the radially inner end portion and decreases toward the radially outer end portion, and from the equal thickness portion. In the area of the half thrust bearing on the center side in the circumferential direction, the half thrust bearing is characterized in that the axial distance is the smallest at the radially inner end and increases towards the radially outer end. Is done.
Here, the axial distance is the smallest on the outer peripheral side of the half thrust bearing in any cross section parallel to the surface including both end faces in the circumferential direction of the half thrust bearing, and toward the center in the circumferential direction. It is getting bigger.
The back surface of the half thrust bearing may be flat and located in the reference plane.
When the half thrust bearing is viewed from the direction perpendicular to the circumferential end face of the half thrust bearing, the sliding surface may have a convex contour that protrudes most at the center in the circumferential direction. The outline of the sliding surface can be composed of a curve.
Further, the difference between the maximum axial direction distance of the half thrust bearing at the radially outer end of the circumferential central portion and the axial distance of the radially outer end of both circumferential ends may be 50 to 800 μm. .
The two planes constituting the sliding surface may be axisymmetric with respect to the center line of the half thrust bearing extending in the circumferential center.
One equal-thickness part may be formed at a position at a circumferential angle of 45 ° from each circumferential end face toward the circumferential central part.

  Here, the crankshaft is a member having a journal portion, a crankpin portion, and a crank arm portion. Further, the half thrust bearing is a member having a shape obtained by dividing an annular ring into approximately half, but is not intended to be strictly half.

According to the half thrust bearing of the present invention having the above-described configuration, the inclination angle of the thrust collar surface of the srank shaft with respect to the sliding surface of the half thrust bearing is increased due to the bending of the crankshaft during operation of the internal combustion engine. Even in this case, the contact position between the sliding surface and the thrust collar surface sequentially moves in the circumferential direction as the crankshaft rotates, so that only the sliding surfaces near both circumferential ends of the half thrust bearing are always connected to the crankshaft. This prevents contact with the thrust collar surface, and damage to the sliding surface of the half thrust bearing hardly occurs.
Further, in the thrust bearing of the present invention, the axial distance is the smallest at the radially inner end portion and the outer end portion in the region in the circumferential central portion side of the position of the equal thickness portion where the axial distance is constant over the radial direction. It is getting bigger towards the department. For this reason, even when the thrust collar surface is largely inclined toward the gap due to the deflection of the crankshaft during the operation of the internal combustion engine, the sliding surface in the region on the circumferential center side of the half thrust bearing is thrust over the entire length in the radial direction. Since it contacts the collar surface and supports the axial load f of the crankshaft, damage is unlikely to occur.
On the other hand, in the conventional half thrust bearing, the sliding surface near the central portion in the circumferential direction is formed so that the axial distance is constant over the radial direction. If it is greatly inclined to the side, only the sliding surface on the radially inner end side comes into contact with the thrust collar surface in the region near the center in the circumferential direction, and damage may occur.

It is a disassembled perspective view of a bearing apparatus. 1 is a front view of a half thrust bearing of Example 1. FIG. FIG. 3 is a side view of the half thrust bearing of FIG. FIG. 3 is a side view of the half thrust bearing of FIG. It is A1-A1 sectional drawing of the half thrust bearing of FIG. It is A2-A2 sectional drawing of the half thrust bearing of FIG. It is A3-A3 sectional drawing of the half thrust bearing of FIG. It is a front view of a half bearing and a thrust bearing. It is sectional drawing of a bearing apparatus. FIG. 9 is a front view of the upper half bearing of FIG. 8. It is the bottom view which looked at the half bearing of Drawing 10 from the inner side of the diameter direction. It is sectional drawing which shows the contact state of the thrust collar surface in operation and a pair of half thrust bearing. It is a figure which shows the change of the inclination with respect to the sliding surface of the thrust collar surface in driving | operation seen from the circumferential direction both end surface side. It is a figure which shows the inclination with respect to the sliding surface of the thrust collar surface in driving | operation seen from the circumferential direction both end surface side. It is a figure which shows the inclination with respect to the sliding surface of the thrust collar surface in driving | operation seen from the circumferential direction both end surface side. It is a figure which shows the inclination with respect to the sliding surface of the thrust collar surface in driving | operation seen from the circumferential direction both end surface side. It is a figure which shows the inclination with respect to the sliding surface of the thrust collar surface in driving | operation seen from the circumferential direction both end surface side. It is a figure which shows the contact position of the sliding surface and thrust collar surface which looked at the sliding surface from the front side corresponding to FIG. 13A. It is a figure which shows the contact position of the sliding surface and thrust collar surface which looked at the sliding surface from the front side corresponding to FIG. 13B. It is a figure which shows the contact position of the sliding surface and thrust collar surface which looked at the sliding surface from the front side corresponding to FIG. 13C. It is a figure which shows the contact position of the sliding surface and thrust collar surface which looked at the sliding surface from the front side corresponding to FIG. 13D. It is a figure which shows the contact position of the sliding surface and thrust collar surface which looked at the sliding surface from the front side corresponding to FIG. 13E. It is a front view of the half thrust bearing of other forms of the present invention. FIG. 16 is a side view of the vicinity of a circumferential end of the half thrust bearing of FIG. 15.

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

(Overall configuration of bearing device)
First, the whole structure of the bearing device 1 having the half thrust bearing 8 of the present invention will be described with reference to FIGS. As shown in FIGS. 1, 8 and 9, a bearing housing 4 configured by attaching a bearing cap 3 to the lower part of the cylinder block 2 has a bearing hole (holding hole) 5 which is a circular hole penetrating between both side surfaces. Receiving seats 6 and 6 which are annular recesses are formed on the peripheral edge of the bearing hole 5 on the side surface. Half bearings 7 and 7 that rotatably support the journal portion 11 of the crankshaft are fitted into the bearing hole 5 in a cylindrical shape. Half thrust bearings 8 and 8 that receive an axial force f (see FIG. 9) via the thrust collar surface 12 of the crankshaft are fitted into the receiving seats 6 and 6 in an annular shape.

  As shown in FIG. 8, a lubricating oil groove 71 is formed on the inner peripheral surface of the half bearing 7 on the cylinder block 2 side (upper side) of the half bearing 7 constituting the main bearing, and the lubricating oil groove 71. A through hole 72 penetrating the outer peripheral surface is formed inside (see also FIGS. 10 and 11). The lubricating oil groove 71 can also be formed in both upper and lower half bearings. The half bearing 7 also has a crush relief 73 on a sliding surface 75 adjacent to the circumferential end surfaces 74.

(Configuration of half thrust bearing)
Next, the structure of the half thrust bearing 8 of Example 1 is demonstrated using FIGS. The half thrust bearing 8 of the present embodiment is formed into a semi-annular flat plate by a bimetal obtained by bonding a thin bearing alloy layer to a steel back metal layer. The half thrust bearing 8 includes a sliding surface 81 (bearing surface) facing in the axial direction, and the sliding surface 8 is composed of a bearing alloy layer. The sliding surface 81 is composed of two flat surfaces with the central portion 85 in the circumferential direction of the half thrust bearing 8 as a boundary. These two planes are preferably axisymmetric with respect to a center line (boundary) extending through the circumferential central portion 85 of the half thrust bearing 8. In addition, two oil grooves 81a and 81a are formed between the circumferential end surfaces 83 and 83 in the sliding surface 81 in order to improve the oil retaining property of the lubricating oil.

  The half thrust bearing 8 defines a reference surface 84 that is perpendicular to the axial direction, and within this reference surface 84 is a substantially flat back surface 84a adapted to be placed on the seat 6 of the cylinder block 2. (See FIG. 3). Further, the half thrust bearing 8 has a sliding surface 81 that is axially separated from the reference surface 84 (back surface 84a), and the sliding surface 81 receives an axial force f through the thrust collar surface 12 of the crankshaft. (See FIG. 9). The half thrust bearing 8 has a maximum axial distance from the reference surface 84 to the sliding surface 81 at the circumferential central portion 85 of the half thrust bearing 8 at any radial position of the half thrust bearing 8. The half thrust bearing is formed so as to decrease toward both ends in the circumferential direction. Therefore, for example, even in the radial center position of the half thrust bearing 8 (the one-dot chain line position in FIG. 2), the axial distance from the reference surface 84 to the sliding surface 81 is the maximum (TC) in the circumferential center portion 85. It will be appreciated that the circumferential end 86 is the smallest (TE).

In the present embodiment, the axial distance from the reference surface 84 (back surface 84 a) to the sliding surface 81 matches the bearing wall thickness T of the half thrust bearing 8.
In the present embodiment, between each circumferential end face 83 and the circumferential central portion 85, a constant thickness portion M (see FIG. 5) in which the bearing wall thickness is constant between the radially outer end and the radially inner end. 5) is formed. More specifically, the equal-thickness portion M is disposed at a circumferential angle of 45 ° from each circumferential end surface 83 of the half thrust bearing 8 toward the circumferential central portion 85. In the region XE on the direction end face 83 side, the bearing wall thickness is maximum at the radially inner end (thickness TI) and decreases toward the radially outer end (thickness TO) (see FIG. 6). On the other hand, in the region XC on the circumferential central portion 85 side with respect to the equal thickness portion M, the bearing wall thickness is minimum at the radially inner end portion (thickness TI) and increases toward the radially outer end portion (thickness TO). (See FIG. 7).
In other words, the sliding surface 81 (two planes) having the above-described configuration has a bearing wall thickness from the radially outer end of the circumferential central portion of the half thrust bearing 8 toward the radially outer end of both circumferential ends. It consists of a plane inclined with respect to the back surface 83 so that the number of Therefore, the bearing wall thickness is the surface including the circumferential end surfaces 83 in both the region XC on the circumferential center 85 side of the uniform thickness portion M and the region XE on the circumferential end surfaces 83 side of the uniform thickness portion M. It will be understood from FIG. 4 that, in any parallel cross section, it is the smallest on the outer peripheral side of the half thrust bearing 8 and increases toward the central portion 85 in the circumferential direction.
In the portion of the sliding surface 81 where the oil groove 81a is formed, the axial distance from the rear surface 84a to the virtual sliding surface (the extended surface of the sliding surface 81) when the oil groove 81a is not formed is The half thrust bearing 8 is formed so as to satisfy the above relationship.
Further, the arrangement position of the equal-thickness portion M is not limited to a position at a circumferential angle of 45 ° from each circumferential end surface 83 of the half thrust bearing 8 toward the circumferential central portion 85, One equal thickness portion M may be arranged in a range of a circumferential angle of 40 ° to 50 ° toward the direction center portion 85.

  As described above, the bearing wall thickness TE at both circumferential ends of the half thrust bearing 8 is formed smaller than the bearing wall thickness TC at the circumferential central portion (see FIG. 3). Therefore, the sliding surface 81 of the half thrust bearing 8 has a convex outline with the circumferential center portion 85 protruding most when viewed from a direction perpendicular to the surfaces including both circumferential end surfaces of the half thrust bearing 8. (See FIG. 3). More specifically, when used for a crankshaft of a small internal combustion engine for a passenger car or the like (having a journal portion having a diameter of about 30 to 100 mm), the radially outer end of the circumferential central portion 85 of the half thrust bearing 8 The difference between the bearing wall thickness at the portion and the bearing wall thickness at the radially outer end portion at both ends in the circumferential direction is, for example, 50 to 800 μm, and more preferably 200 to 400 μm. However, these dimensions are only examples, and the difference in bearing wall thickness is not limited to this dimension range.

(Function)
Next, the operation of the conventional half thrust bearing 8 will be described with reference to FIGS.

  Generally, the half bearing 7 is concentric with the half thrust bearing 8, and the plane including the circumferential end faces 74 of the half bearing 7 constituting the main bearing includes the circumferential end faces 83 of the half thrust bearing 8. It arrange | positions so that it may correspond with a plane substantially.

  During operation of the internal combustion engine, particularly under operating conditions in which the crankshaft rotates at a high speed, the crankshaft is bent (bending in the axial direction), and the vibration of the crankshaft increases. Due to this large vibration, an axial force f toward the sliding surface 81 of the half thrust bearing 8 is periodically generated on the crankshaft. The sliding surface 81 of the half thrust bearing 8 receives this axial force f.

When a pair of half thrust bearings 8, 8 is assembled to each axial end portion of the main bearing consisting of a pair of half bearings 7, 7, a pair of half thrust bearings are assembled when assembled to the split bearing housing 4. If the positions of the end surfaces 83 of the 8, 8 are shifted in the axial direction, the gap between the sliding surface 81 of one half thrust bearing 8 and the thrust collar surface 12 of the crankshaft becomes the other half. The clearance becomes larger than the gap between the sliding surface 81 of the split thrust bearing 8 and the thrust collar surface 12 (see FIG. 12). Alternatively, when only one half thrust bearing 8 is assembled at each end in the axial direction of the main bearing, the side surface of the split bearing housing 4 on which the half thrust bearing 8 is not disposed and the thrust collar surface 12 of the crankshaft. A large gap is formed between the two. When the internal combustion engine is operated in a state where such a gap is formed and the crankshaft is bent, the thrust collar surface 12 of the crankshaft is further inclined toward the larger gap. When the crankshaft rotates with such a large inclination toward the gap side, the inclination of the thrust collar surface 12 with respect to the half thrust bearing 8 in the plane including both circumferential end faces 83 of the half thrust bearing 8 becomes larger. In addition, since only the sliding surfaces 81 near both ends in the circumferential direction of the half thrust bearing 8 are always in direct contact with the thrust collar surface 12 of the crankshaft, damage (fatigue) is likely to occur as described above.
More specifically, when the half thrust bearing 8 is viewed from a direction perpendicular to the surface including both circumferential end faces 83, the thrust collar surface 12 of the crankshaft is (1) rotation of the crankshaft of the half thrust bearing 8. The rear side in the rotational direction of the crankshaft of the half thrust bearing 8 is from the state of being inclined toward the circumferential end on the rear side in the direction until being parallel to the sliding surface 81 of the half thrust bearing 8. (2) Immediately after being in parallel with the sliding surface 81, (2) the circumferential end surface on the front side in the rotational direction of the crankshaft of the half thrust bearing 8 Is inclined only to the sliding surface 81 near the circumferential end on the front side in the rotational direction of the crankshaft of the half thrust bearing 8.

  Here, as described in Patent Document 2, even if a crowning surface composed of a curved surface is provided on the outer diameter side of the sliding surface of the half thrust bearing, the axial direction from the reference surface 84 to the sliding surface 81 In the case where the half thrust bearing 8 is not formed so that the distance is maximum at the center in the circumferential direction at any radial position, in other words, it is half from the direction perpendicular to the surface including the circumferential end surfaces 83. When the thrust bearing 8 is viewed, when the contour of the sliding surface 81 of the half thrust bearing 8 is not the most protruding convex shape at the center in the circumferential direction (for example, half from the direction perpendicular to the surface including the circumferential end surfaces 83) When the split thrust bearing 8 is viewed, the outline of the sliding surface 81 is a straight line). For the above reason, the sliding surface 81 in the vicinity of the circumferential end of the half thrust bearing 8 and the thrust collar surface of the crankshaft. 12 in direct contact with damage Kiyasui.

Alternatively, as described in Patent Document 3, an inclined surface (thrust relief) is formed on the sliding surface of the half thrust bearing, extending from the circumferential end of the half thrust bearing to approximately the half of the height to the top. Even if the inclination angle of the inclined surface with respect to the sliding surface is thereby reduced, the sliding surface of the half thrust bearing 8 when viewed from the direction perpendicular to the surfaces including the circumferential end surfaces 83 of the half thrust bearing 8 is obtained. When the contour of 81 is not the most protruding convex shape in the central portion in the circumferential direction, the sliding surface 81 (inclined surface) near the circumferential end of the half thrust bearing and the thrust collar surface 12 of the crankshaft are also particularly for the above reasons. Are in direct contact with each other and damage is likely to occur.
Furthermore, in the half thrust bearing described in Patent Document 3, the bearing wall thickness of the inclined surface is such that the outer end in the radial direction from the inner end in the radial direction of the thrust bearing except the circumferential end of the half thrust bearing. Therefore, the sliding surface (inclined surface) on the outer diameter side in the vicinity of the circumferential end of the half thrust bearing and the thrust collar surface 12 of the crankshaft are in direct contact with each other, and damage is more likely to occur.

(effect)
Next, the effect of the half thrust bearing 8 of the present embodiment will be described with reference to FIGS.

13A to 13E show sliding when the half thrust bearing 8 is viewed from a direction perpendicular to the surface including the circumferential end faces 83 of the half thrust bearing 8 (that is, in the plane including the circumferential end faces 83). FIGS. 14A to 14E correspond to FIGS. 13A to 13E when the sliding surface 81 of the half thrust bearing 8 is viewed from the front side. The change of the contact position of the sliding surface 81 and the thrust collar surface 12 is shown. 14A to 14E indicate contact portions between the sliding surface 81 of the half thrust bearing 8 and the thrust collar surface 12 (the position of the sliding surface that receives the load most by the contact). For example, from FIG. 13B and the corresponding FIG. 14B, even after the contact portion between the sliding surface 81 and the thrust collar surface 12 is separated from the vicinity of the circumferential end portion shown in FIG. 14A, the circumferential central portion shown in FIG. It will be understood that the thrust collar surface 12 is inclined with respect to the sliding surface 81 in a plane including both circumferential end surfaces 83 until reaching.
In the half thrust bearing 8 of the present embodiment, the axial distance T from the back surface 84 a (reference surface 84) to the sliding surface 81 is the circumferential central portion 85 at any radial position of the half thrust bearing 8. At the maximum, it decreases toward both ends in the circumferential direction. In addition, between each circumferential end face 83 and the circumferential central portion 85, only one constant thickness portion M having a constant axial distance between the radially outer end and the radially inner end is formed. The equal thickness portion M is arranged at a circumferential angle of 45 ° from each circumferential end of the half thrust bearing 8 toward the circumferential central portion. The axial distance is maximum at the radially inner end (thickness TI) in the region XE closer to the circumferential end than the uniform thickness M, and decreases toward the radially outer end (thickness TO). Further, in the region XC on the circumferential center side with respect to the equal thickness portion M, the radial inner end portion (thickness TI) is the smallest and increases toward the radially outer end portion (thickness TO).
With this configuration, the axial distance is the smallest on the outer circumferential side of the half thrust bearing 8 and increases toward the circumferential central portion 85 in an arbitrary cross section parallel to the plane including the circumferential end faces 83. It will be understood that
13A to 13E, even if the inclination change of the thrust collar surface 12 with respect to the back surface 84a of the half thrust bearing 8 occurs as shown in FIGS. 13A to 13E, the sliding surface 81 and the thrust collar surface 12 as shown in FIGS. Of the half thrust bearing 8 from the circumferential end on the rear side in the rotational direction of the crankshaft (FIGS. 13A and 14A) to the circumferential end on the front side in the rotational direction of the crankshaft (FIGS. 13E and 14E). As the crankshaft rotates, it moves sequentially in the circumferential direction. For this reason, in the half thrust bearing 8 of the present embodiment, only the sliding surfaces 81 near both ends in the circumferential direction are always in direct contact with the thrust collar surface 12 of the crankshaft and are prevented from being damaged (fatigue).
Further, in the half thrust bearing 8 of this embodiment, the axial distance T is maximum at the radially inner end of the half thrust bearing 8 in the region XE on the circumferential end face 83 side of the equal thickness portion M as described above. The slanking shaft is formed by the deflection of the crankshaft generated during operation of the internal combustion engine in a plane including both circumferential end surfaces of the half thrust bearing. Even when the thrust collar surface 12 is inclined to the sliding surface of the half thrust bearing, the region on the outer diameter side of the sliding surface 81 near both ends in the circumferential direction of the half thrust bearing 8 is in strong contact with the thrust collar surface 12. Is prevented.
Further, in the thrust bearing 8 of the present embodiment, the axial distance is minimum at the radially inner end in the region XC on the circumferential center side with respect to the position of the equal thickness portion M where the axial distance is constant in the radial direction. Thus, it is formed so as to increase toward the radially outer end (see FIG. 7). For this reason, even when the thrust collar surface 12 is largely inclined toward the gap due to the deflection of the crankshaft that occurs during operation of the internal combustion engine (see FIG. 12), the sliding surface in the circumferential central region of the half thrust bearing 8 Since it is in contact with the thrust collar surface over the entire length in the radial direction and supports the axial load f of the crankshaft, damage is unlikely to occur.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and design changes that do not depart from the gist of the present invention are included in the present invention. Should be understood.

  For example, in the embodiment, the bearing device 1 of the type in which the half bearing and the half thrust bearing are separated has been described, but the present invention is not limited to this, and the half bearing and the half thrust bearing are integrated. The present invention can also be applied to a bearing device 1 of a simplified type.

As shown in FIG. 15, the present invention can also be applied to a half thrust bearing 108 having a protruding portion 88 protruding radially outward for positioning and rotation prevention. In addition, the protrusion part 88 does not need to satisfy the structure of the axial direction distance T mentioned above. Further, as shown in FIGS. 15 and 16, a thrust relief 82 may be provided in the vicinity of both ends in the circumferential direction of the sliding surface 81 of the half thrust bearing. Further, as shown in FIG. 16, the back surface relief 87 can be formed by providing tapers at both ends in the circumferential direction of the back surface 84 a opposite to the sliding surface 81 of the half thrust bearing 108. In addition, when the thrust relief 82 and the back surface relief 87 are provided, the bearing wall thickness TE at the radially outer end portion at both circumferential ends of the above-described half thrust bearing is the case where the thrust relief 82 and the back surface relief 87 are not provided. Is defined by an axial distance between an imaginary sliding surface 81 (a surface obtained by extending the sliding surface 81 to both ends in the circumferential direction) and a virtual back surface 84a (a surface obtained by extending the back surface 84a to both ends in the circumferential direction). .
Further, as shown in FIGS. 15 and 16, the circumferential length of the half thrust bearing 108 is formed shorter than the position HR of the circumferential end face of the normal half thrust bearing 8 shown in Embodiment 1 by a predetermined length S1. May be. Further, the half thrust bearing 108 may be cut out in an arc shape with a radius R in the vicinity of both ends in the circumferential direction. In that case, the bearing wall thickness T at the circumferential end of the half thrust bearing can be expressed by the length S1 or the bearing wall thickness at the circumferential end of the half thrust bearing when notches are not formed. it can.

  Further, chamfering can be formed along the circumferential direction at the radially outer edge and / or the radially inner edge of the sliding surface of the half thrust bearing. In this case, the bearing wall thickness TI at the radially inner end of the half thrust bearing and the bearing wall thickness TO at the radially outer end are the radially inner end of the half thrust bearing when no chamfer is formed. It can be represented by the bearing wall thickness at the end portion and the outer diameter side end.

  The above embodiment relates to a half thrust bearing in which two oil grooves 181a are formed on the sliding surface. However, the present invention is not limited to this, and the half thrust bearing has one or more oil grooves. May be. Alternatively, the oil groove 181a may be formed so as to correspond to the equal thickness portion M at a circumferential angle of 45 ° as shown in FIG.

  The sliding surface 81 is composed of two flat surfaces with the circumferential central portion 85 of the half thrust bearing 8 as a boundary, but the corner portion formed at the boundary between the two flat surfaces has a smooth curved surface. You can also.

  Moreover, although the said Example demonstrated the case where four half thrust bearings were used for a bearing apparatus, this invention is not limited to this, At least one half thrust bearing by this invention is used. By doing so, a desired effect can be obtained. In the bearing device, the half thrust bearing of the present invention may be integrally formed on one or both end surfaces in the axial direction of the half bearing that rotatably supports the crankshaft.

DESCRIPTION OF SYMBOLS 1 Bearing apparatus 11 Journal part 12 Thrust collar surface 2 Cylinder block 3 Bearing cap 4 Bearing housing 5 Bearing hole (holding hole)
6 Seat 7 Half bearing 71 Lubricating oil groove 72 Through hole 73 Crush relief 74 Both ends in the circumferential direction 75 Sliding surface 8 Half thrust bearing 81 Sliding surface 81a Oil groove 82 Thrust relief 83 Both ends in the circumferential direction 84 Reference surface 84a Back face 85 Circumferential center part 86 Circumferential end parts 87 Rear relief 88 Projection part 108 Half thrust bearing 181a Oil groove f Axial force T Bearing wall thickness M Constant thickness part XC Central part side area XE End part side area

Claims (6)

A semi-annular half thrust bearing for receiving an axial force of a crankshaft of an internal combustion engine, comprising a sliding surface for receiving the axial force and a back surface opposite to the sliding surface A half thrust bearing having a reference surface perpendicular to the axial direction on the back side,
The sliding surface is composed of two planes with the center in the circumferential direction of the half thrust bearing as a boundary,
The axial distance from the reference surface to the sliding surface is the largest in the circumferential center of the half thrust bearing at any radial position of the half thrust bearing, and the circumferential direction of the half thrust bearing It becomes smaller toward both ends,
The axial direction between the radially inner end and the radially outer end of the half thrust bearing at a circumferential angle of 40 ° to 50 ° from each circumferential end surface toward the circumferential central portion. Only one iso-thick part with a constant distance is formed,
In the region of the half thrust bearing on the circumferential end side from the equal thickness part, the axial distance is maximum at the radially inner end and decreases toward the radially outer end. Further, in the region of the half thrust bearing closer to the circumferential central portion than the equal thickness portion, the axial distance is minimum at the radially inner end portion and increases toward the radially outer end portion. A half thrust bearing characterized by that.   The half thrust bearing according to claim 1, wherein the back surface is flat and is located in the reference plane.   When the half thrust bearing is viewed from a direction perpendicular to the circumferential end face of the half thrust bearing, the contour of the convex shape in which the sliding surface of the half thrust bearing protrudes most at the circumferential central portion. The half thrust bearing according to claim 1 or 2, wherein   The difference between the maximum axial direction distance of the half thrust bearing at the radially outer end of the circumferential central portion and the axial distance of the radially outer ends of both circumferential ends is 50 to 800 μm. The half thrust bearing according to any one of Items 1 to 3.   5. The half thrust bearing according to claim 1, wherein the two planes are line symmetric with respect to a center line of the half thrust bearing extending in the circumferential central portion.   6. The half according to claim 1, wherein the one equal-thickness portion is formed at a circumferential angle of 45 ° from each circumferential end face toward the circumferential central portion. Split thrust bearing.