JP6115994B2 - Bearing device - Google Patents

Description

  The present invention relates to a thrust bearing and a bearing device that receive 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 generally disposed on both end faces facing the axial direction of the half bearing.

  Then, the lubricating oil is fed 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, and then the half thrust bearing To be supplied.

  Conventionally, of the half thrust bearings on both end faces, the sliding surface of the half thrust bearing (I) disposed on the transmission side is adapted to support an axial force F that is input shockably from the crankshaft. Was composed. On the other hand, the sliding surface of the half thrust bearing (II) arranged on the side opposite to the transmission side was not affected by the axial force F.

JP-A-11-2011145

  In recent years, when the crankshaft and the transmission are connected by the clutch, the axial force F that is input shockably to the crankshaft tends to increase. For this reason, the amount of displacement of the crankshaft in the axial direction also tends to increase.

  Therefore, if foreign matter is mixed in the lubricating oil fed to the main bearing, the mixed foreign matter will be present at the moment when the shocking axial force F from the crankshaft is applied to the sliding surface of the half thrust bearing (I). Both the lubricating oil and the lubricating oil are easily pushed away between the sliding surface of the half thrust bearing (II) disposed on the opposite side of the transmission and the thrust collar surface of the crankshaft.

  For this reason, the foreign matter rolls between the sliding surface of the half thrust bearing and the thrust collar surface of the rotating crankshaft, and the sliding surface of the half thrust bearing is damaged by wear and seizure. It became easy to receive.

  Therefore, an object of the present invention is to provide a half thrust bearing that is excellent in discharging foreign matters and a bearing device including the half thrust bearing.

  In order to solve the above-described problems, a half thrust bearing according to the present invention is a half ring-shaped half thrust bearing that receives an axial force of a crankshaft of an internal combustion engine, and supports the crankshaft in the axial direction. And a reverse wedge surface formed so that the wall thickness becomes thinner toward the rotation direction of the crankshaft.

  Here, the crankshaft intends a member including a journal portion, a crankpin portion, and a crank arm portion. Further, the half thrust bearing is intended to be a member having a shape obtained by dividing an annular shape into approximately halves, but is not intended to be halved in a strict sense.

  As described above, the half thrust bearing of the present invention includes a sliding surface that supports the crankshaft in the axial direction, and a reverse wedge surface that is formed so that the wall thickness decreases in the rotation direction of the crankshaft. Provided on one side. For this reason, due to the reverse wedge gap formed by the reverse wedge surface, foreign matter mixed in the lubricating oil is discharged to the outside of the bearing, and the sliding surface of the half thrust bearing is less likely to be damaged.

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. It is a front view of the thrust bearing comprised combining a pair of half thrust bearing. It is sectional drawing of a bearing apparatus. It is sectional drawing explaining the effect | action of the half thrust bearing of Example 1. FIG. It is a front view explaining the effect | action of the half thrust bearing of Example 1. FIG. It is a front view of the half thrust bearing of another form. It is a front view of the half thrust bearing of Example 2. It is a side view of the half thrust bearing of another form. FIG. 10 is a Y2 arrow side view of the half thrust bearing of FIG. 9. FIG. 6 is a side view of the vicinity of an oil groove of a half thrust bearing according to another embodiment. It is sectional drawing explaining the effect | action of the half thrust bearing which has a wedge surface for the comparison.

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

(Configuration of bearing device)
First, the whole structure of the bearing apparatus 1 provided with the half thrust bearing 8 of this invention is demonstrated using FIG.1, FIG4 and FIG.5. As shown in FIGS. 1, 4, and 5, the bearing housing 4 configured by attaching the bearing cap 3 to the lower portion of the cylinder block 2 is formed with a bearing hole 5 that is a circular hole penetrating between both side surfaces. On the side of the bearing hole 5 on the side, receiving seats 6 and 6 that are annular recesses are formed. Half bearings 7 and 7 that rotatably support the journal portion 11 of the crankshaft are fitted in the bearing hole 5 in a cylindrical shape. Half thrust bearings 8 and 8 that receive an axial force F through a thrust collar 12 of the crankshaft are fitted in the seat 6 in an annular combination.

  That is, the bearing device 1 according to the present embodiment includes a journal portion 11 as a crankshaft of an internal combustion engine, a pair of half bearings 7 and 7 that support the radial force of the crankshaft, and an axial force of the crankshaft. Two pairs (four) of half thrust bearings 8, 8, 8, 8, and a bearing hole 5 and a half thrust bearing as a holding hole penetratingly formed to hold the pair of half bearings 7, 7 A bearing housing 4 having receiving seats 6 and 6 formed on both side surfaces for arranging 8, 8, 8, and 8 is provided.

  Of the seats 6, 6 on both sides of the bearing housing, the seat 6 on the side opposite to the side to which the axial force of the crankshaft is input (the left side in FIG. 5) has a reverse wedge described later. Two half thrust bearings 8, 8 having a surface 82 are arranged in an annular combination.

  Thus, in the bearing device 1 of the present embodiment, of the seats 6 and 6 on both side surfaces of the bearing housing 4, the side opposite to the side where the axial force F is input, in other words, far from the transmission. One or two half thrust bearings 8 having a reverse wedge surface 82 to be described later are arranged on the seat 6 on the side or on the side opposite to the output side of the rotational force of the crankshaft.

(Configuration of half thrust bearing)
Next, the structure of the half thrust bearing 8 of an Example is demonstrated using FIGS. The half thrust bearing 8 of the present embodiment is formed into a semi-annular flat plate by a bimetal in which a thin bearing alloy layer is bonded to a steel back metal layer. The half thrust bearing 8 has a sliding surface 81 (that is, a bearing surface) which is a side surface constituted by a bearing alloy layer, and a rotation direction of the journal portion 11 of the crankshaft (FIG. 2) on the same side surface as the sliding surface 81. And a reverse wedge surface 82 formed so that the wall thickness becomes thinner in the direction of the arc of the arrow). In addition, the half thrust bearing 8 can also have a thrust relief (not shown) near both ends.

  As shown in the front view of FIG. 2, one reverse wedge surface 82 according to the present embodiment is disposed substantially at the center of both end surfaces in the circumferential direction of the half thrust bearing 8. However, the position of the reverse wedge surface 82 is not limited to the substantially center, and may be arranged at any position other than the vicinity of both ends.

  Further, at least one reverse wedge surface 82 may be disposed on one half thrust bearing 8 and a plurality of reverse wedge surfaces 82 may be disposed on one half thrust bearing 8. As shown in FIG. 8, it is preferable to arrange at least three reverse wedge surfaces 82,. In FIG. 8, three reverse wedge surfaces 82,... Are arranged at positions of 45 degrees, 90 degrees, and 135 degrees, respectively.

  The front shape of the reverse wedge surface 82 of the present embodiment is formed in a fan shape (fan surface shape) surrounded by two radii and two large and small circular arcs forming concentric circles therebetween. The circumferential angle (center angle) θ that defines the circumferential range of the reverse wedge surface 82 is preferably 5 ° to 35 °. In addition, when arrange | positioning several reverse wedge surfaces 82 and ..., it is preferable to make each reverse wedge surface 82 into the said range.

  Here, the front shape of the reverse wedge surface 82 does not have to be a fan shape as described above. For example, the reverse wedge surface 82 is surrounded by two parallel line segments and two large and small circular arcs forming concentric circles therebetween. It may be a shape.

  As shown in the side view of FIG. 3, the reverse wedge surface 82 is formed so that the wall thickness of the half thrust bearing 8 decreases linearly (linearly) in the rotation direction of the crankshaft. However, the reverse wedge surface 82 may be curved so that the wall thickness decreases in a curved manner toward the rotation direction of the crankshaft. The reverse wedge surface 82 is formed such that the depth from the sliding surface 81 is constant in the radial direction over the entire length from the inner diameter side to the outer diameter side. The depth D1 of the deepest portion of the reverse wedge surface 82 from the sliding surface 81 is preferably 0.005 mm to 0.075 mm.

  In the half thrust bearing 8 of the present embodiment, a stepped surface 83 is formed between the end of the reverse wedge surface 82 in the rotational direction of the crankshaft and the sliding surface 81. In other words, the wall thickness of the half thrust bearing 8 gradually decreases at the reverse wedge surface 82 in the rotational direction of the crankshaft, and increases discontinuously through the step surface 83. Return to the thickness of the bearing 8. Since the step surface 83 is formed so as to be substantially orthogonal to the sliding surface 81, it forms an acute angle with respect to the reverse wedge surface 82.

(Function)
Next, the effect | action of the half thrust bearing 8 of a present Example is demonstrated using FIGS.

(Lubrication action)
In the bearing device 1, the lubricating oil pressurized and discharged from an oil pump (not shown) passes through the through hole 72 passing through the wall of the half bearing 7 from the internal oil passage of the cylinder block 2, and the half bearing. 7 is supplied to the lubricating oil groove 71 on the inner peripheral surface of the roller 7. A part of the lubricating oil supplied into the lubricating oil groove 71 is supplied to the inner peripheral surface of the main bearing, and a part of the lubricating oil enters the opening of the internal oil passage of the crankshaft (not shown) on the surface of the journal portion and enters the crankpin side. Partly flows out from both ends in the width direction of the main bearing through the gap between the surface of the crash relief 73 of the pair of half bearings 7 and 7 constituting the main bearing and the surface of the journal portion 11 of the crankshaft. To do.

  Lubricating oil that has flowed to the outside from both ends in the width direction of the main bearing (half bearing 7) mainly flows in a gap between the sliding surface 81 of the half thrust bearing 8 and the thrust collar 12 surface of the crankshaft.

  Immediately after the crankshaft and the transmission are connected from the state where they are disconnected by the clutch, an axial torque reaction force is generated, and the axial force F is applied to the crankshaft from the output side end of the rotational force of the crankshaft. Input is made shockingly, and the crankshaft is displaced in the opposite direction to the output side. The sliding surface 81 of the half thrust bearing 8 receives this axial force F as a maximum load.

  At this time, if foreign matter is mixed in the lubricating oil, the moment between the axial force F from the crankshaft and the sliding surface of the half thrust bearing 8 is impacted between the main bearing surface and the journal portion surface. The foreign matter mixed in the lubricating oil is pushed away between the sliding surface 81 of the half thrust bearing 8 and the thrust collar 12 surface of the crankshaft that are disposed on the side surface opposite to the transmission together with the lubricating oil.

(Foreign matter discharge action)
As shown in FIGS. 6 and 7, the foreign matter sent to the gap between the sliding surface 81 and the thrust collar 12 together with the lubricating oil forms a reverse wedge gap (between the extension line of the sliding surface 81 and the reverse wedge surface 82. Invade the gap. Foreign matter that has entered the reverse wedge gap (indicated by black circles in FIGS. 6 and 7) is the front side in the rotation direction along with the lubricating oil flowing along the reverse wedge gap along the surface of the crankshaft (the surface of the thrust collar 12). It flows toward.

  As shown in FIG. 6, the reverse wedge surface 82 moves away from the surface of the thrust collar 12 toward the front side in the rotation direction, and therefore the oil flow of the lubricating oil flowing along the surface of the reverse wedge surface 82 in the reverse wedge gap Is gradually weaker toward the front side in the rotation direction. For this reason, as shown in FIG. 7, foreign matter mixed in the lubricating oil is discharged to the outside together with the lubricating oil flowing out from the outer diameter side end of the half thrust bearing 8 while flowing in the reverse wedge gap. Will come to be.

  Although a part of the foreign matter reaches the end of the reverse wedge gap in the rotational direction, a step surface 83 is formed between the reverse wedge surface 82 and the sliding surface 81. The stepped surface 83 prevents foreign matter from entering the sliding surface 81 on the front side, and the foreign matter is discharged together with the lubricating oil from the gap at the end portion on the outer diameter side of the half thrust bearing 8.

  Unlike this embodiment, as shown in FIG. 13, a “wedge surface” having a structure gradually approaching the virtual sliding surface toward the front side in the rotation direction of the crankshaft is formed and adjacent to the sliding surface. Then, when a `` wedge gap '' in which the volume gradually decreases toward the front side in the rotation direction of the crankshaft, the lubricating oil flowing in the gap is subjected to a hydrodynamic wedge action and the pressure rises, The flow to the front side in the circumferential direction is strengthened. For this reason, when such a “wedge gap” is formed, if foreign matter is mixed in, the foreign matter is sent to the sliding surface together with the lubricating oil even when compared with a conventional half thrust bearing with a smooth sliding surface. It can be said that it becomes easy to be done.

(effect)
Next, the effects of the half thrust bearing 8 of this embodiment will be listed and described.

(1) The half thrust bearing 8 of the present embodiment is a half ring-shaped half thrust bearing 8 that receives the axial force of the crankshaft of the internal combustion engine, and is a sliding surface that supports the crankshaft in the axial direction. 81 and an inverted wedge surface 82 formed on one side surface so that the wall thickness decreases toward the rotation direction of the crankshaft.

  For this reason, due to the reverse wedge gap formed by the reverse wedge surface 82, foreign matter mixed in the lubricating oil is discharged to the outside of the bearing, and the sliding surface 81 of the half thrust bearing 8 is less likely to be damaged.

(2) A stepped surface 83 is formed between the end of the reverse wedge surface 82 in the rotational direction of the crankshaft and the sliding surface 81, so that the foreign material that has reached the stepped surface 83 has a front side. It becomes easy to prevent the penetration to the sliding surface 81 and to discharge.

(3) The depth D1 from the sliding surface 81 at the deepest part of the reverse wedge surface 82 is set to 0.005 mm to 0.075 mm, thereby improving the discharge of foreign matters while suppressing the amount of leakage of the lubricating oil. be able to.

  That is, when the depth D1 of the reverse wedge surface 82 is less than 0.005 mm, the separation between the crankshaft surface and the reverse wedge surface 82 becomes insufficient, and the effect of weakening the oil flow flowing through the reverse wedge gap becomes insufficient. . On the other hand, when the depth D1 exceeds 0.075 mm, the amount of oil leaking outside from the end portion on the outer diameter side of the half thrust bearing 8 in the reverse wedge gap increases excessively.

(4) By setting the circumferential angle θ that defines the circumferential range of the reverse wedge surface 82 to 5 ° to 35 °, the foreign matter discharge performance is improved.

  That is, when the circumferential angle θ is less than 5 °, the length of the reverse wedge surface 82 (reverse wedge gap) is too short, so that the effect of weakening the oil flow including foreign matter that has entered the reverse wedge gap tends to be insufficient. On the other hand, if the circumferential angle θ exceeds 35 °, the length of the reverse wedge surface 82 becomes long, and the region near the rear side in the axial rotation direction of the reverse wedge surface 82 is too close to the shaft surface. The effect of weakening the oil flow of the lubricating oil entering the wedge gap is almost lost, and the area of the sliding surface of the half thrust bearing is simply reduced.

  Here, when the depth of the reverse wedge surface 82 is D1 and the circumferential angle is θ, the wall thickness decrease rate (D1 / θ) (depth increase rate) for each circumferential angle θ is 0. It is particularly preferable to satisfy .0075 to 0.015 (mm / °) because the amount of excessive lubricating oil leakage can be reduced while having foreign matter discharging ability.

(5) The bearing device 1 of the present embodiment receives a journal portion 11 as a crankshaft of an internal combustion engine, a pair of half bearings 7 and 7 that receive a radial force of the crankshaft, and an axial force of the crankshaft. The half thrust bearings 8, 8, 8, 8 and the bearing hole 5 and the half thrust bearings 8, 8, 8, 8 as holding holes formed through to hold the pair of half bearings 7, 7 are provided. A bearing housing 4 having seats 6, 6 formed on both sides for placement. Of the receiving seats 6 and 6 on both side surfaces of the bearing housing 4, the receiving seat 6 on the side opposite to the side to which the axial force of the crankshaft is input is included in any one or two of the above. Two half thrust bearings 8 are arranged.

  As described above, if any one or two half thrust bearings 8 described above are arranged on the seat 6 on the side opposite to the side on which the axial force of the crankshaft is input, the reverse wedge surface. Due to the reverse wedge gap formed by 82, foreign matter mixed in the lubricating oil is discharged to the outside of the bearing, and the sliding surface 81 of the half thrust bearing 8 is less likely to be damaged.

  Here, on the input side of the axial force F of the crankshaft, the half thrust bearing 8 having the reverse wedge surface 82 of the present invention may be arranged, or the conventional half thrust without the reverse wedge surface. A bearing may be arranged.

  The half thrust bearing having the same shape as the half thrust bearing 8 of the present invention is also fitted into the side seat 6 on the side where the axial force F of the crankshaft of the bearing housing 4 is input. The half thrust bearing can be configured in a common manner, and it is possible to prevent erroneous assembly.

  If a half thrust bearing having the same shape as the half thrust bearing 8 of the present invention is also applied to the input side, the rotation direction of the crankshaft is opposite to that described in the above-described embodiment. For this reason, the reverse wedge surface of the half thrust bearing of the same shape forms a “wedge surface” whose wall thickness increases in the rotational direction. However, since the half thrust bearing on the input side of the axial force F has a structure in which foreign matter is difficult to be sent, the possibility of damage to the sliding surface is low. Furthermore, the “wedge surface” also has the effect of increasing the amount of lubricating oil supplied to the sliding surface of the half thrust bearing on the input side of the axial force F.

  Hereinafter, the half thrust bearings 8B and 8C, which are different from the first embodiment, will be described with reference to FIGS. In addition, the description which attaches | subjects the same code | symbol about the description of the same thru | or equivalent part as the content demonstrated in Example 1, and demonstrates.

(Constitution)
The half thrust bearing 8B (8C) of the present embodiment, like the half thrust bearing 8 of the first embodiment, receives at least the axial force of the crankshaft among the seats 6 and 6 on both side surfaces of the bearing housing. It is arrange | positioned at the receiving seat 6 of the side surface on the opposite side to the side made. As shown in FIGS. 11 and 12, the cross-sectional shape of the reverse wedge surface 82 of the half thrust bearings 8B and 8C is also linearly thinned in the direction of rotation of the crankshaft.

  In the half thrust bearings 8B and 8C of the present embodiment, an arcuate oil groove surface 84 is formed between the end of the reverse wedge surface 82 in the rotational direction of the crankshaft and the sliding surface 81. Has been.

  The oil groove surface 84 is formed on the front side of the reverse wedge surface 82 in the axial rotation direction so as not to affect the foreign matter discharge performance of the reverse wedge surface 82. In addition, although the present Example demonstrated the case where the oil groove surface 84 was formed in circular arc shape, it is not limited to this, Other shapes may be sufficient.

  The half thrust bearing 8B shown in FIG. 11 and the half thrust bearing 8C shown in FIG. In the half thrust bearing 8 </ b> B of FIG. 11, the deepest portion on the farthest side of the reverse wedge surface 82 is disposed so as to coincide with the deepest portion of the oil groove surface 84. In the half thrust bearing 8 </ b> C of FIG. 12, the deepest portion of the reverse wedge surface 82 and the deepest portion of the oil groove surface 84 do not coincide with each other, and the deepest portion of the oil groove surface 84 is at a deeper position.

  The depth GD from the sliding surface 81 to the deepest portion DP of the oil groove surface 84 is at least the depth D1 of the reverse wedge surface 82 and at most 1 mm. That is, when the depth GD is less than the depth D1 of the reverse wedge surface 82, foreign matter is easily sent to the sliding surface along with the oil flow flowing in the circumferential direction of the half thrust bearings 8B and 8C in the oil groove. . On the other hand, when the depth GD exceeds 1 mm, the amount of lubricating oil leaking to the outside from the end portions on the outer diameter side of the half thrust bearings 8B and 8C of the oil grooves increases. The circumferential length GL of the oil groove surface 84 is 1 mm to 5 mm.

  Further, the depth GD from the deepest portion DP of the oil groove surface 84 to the deepest portion DP of the oil groove surface 84 and the length between the deepest portion DP of the oil groove surface 84 and the end portion on the sliding surface side of the oil groove (position DP and sliding surface side). GL ′ (in the configuration of FIG. 11 of the third embodiment, GL ′ = GL), not the linear distance of the end portion of the shaft, but the circumferential length on the virtual sliding surface of the half thrust bearings 8B and 8C. Is preferably GL ′ / GD = 0.5 to 1.0.

(Action / Effect)
Next, actions and effects of the half thrust bearings 8B and 8C of the present embodiment will be listed and described.

  An oil groove surface 84 for supplying lubricating oil is formed between the end portion of the reverse wedge surface 82 in the rotational direction of the crankshaft and the sliding surface 81, thereby improving foreign matter discharge performance. , The supply of lubricating oil can be enhanced. That is, the oil groove surface 84 makes it easy to supply the lubricating oil from the inner peripheral side of the half thrust bearing 8B (8C), and the reverse wedge surface 82 discharges foreign matter from the outer peripheral side of the half thrust bearing 8B (8C). It becomes easy.

  In this case, the relationship between the depth GD of the oil groove surface 84 to the deepest portion DP and the length GL ′ between the deepest portion DP of the oil groove surface 84 and the end portion on the sliding surface side of the oil groove is By setting in the range of GL ′ / GD = 0.5 to 1.0, the lubricating oil flowing in the oil groove is not easily affected by the hydrodynamic wedge action, and foreign matter that has entered the oil groove slides on the sliding surface. Can be suppressed.

  As shown in FIGS. 9 and 10, the present invention can be applied to a half thrust bearing 8 </ b> B having a protruding portion 89 protruding radially outward for positioning and rotation prevention. In addition, the back surface relief can be formed by attaching a taper T to both ends in the circumferential direction of the back surface opposite to the sliding surface 81 of the half thrust bearing 8B. Furthermore, thrust reliefs can be formed at both ends in the circumferential direction of the sliding surface 81 of the half thrust bearings 8B and 8C. The circumferential lengths of the half thrust bearings 8B and 8C can be made shorter by a predetermined length S1 than the normal half thrust bearing 8 shown in the first embodiment. Can be cut out in an arc shape with a radius R.

  Other configurations and operational effects are substantially the same as those in the first embodiment, and thus description thereof is omitted.

  As described above, the first and second embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the first and second embodiments, and the design does not depart from the gist of the present invention. Such modifications are included in the present invention.

  For example, the half thrust bearing 8 of the present invention is preferably arranged on the side opposite to the input side (transmission side) of the axial force of the crankshaft. It can be arranged on both the input side (transmission side) of the axial force of the shaft and the opposite side of the input side, or can be arranged only on the input side (transmission side) of the axial force F of the crankshaft. .

D1 Depth of reverse wedge surface θ Circumferential angle of reverse wedge surface GL, GL ′ Length of oil groove surface in circumferential direction GD Depth of oil groove surface from sliding surface 1 Bearing device 2 Cylinder block 4 Bearing housing 5 Bearing Hole (holding hole)
6 Seat 7 Half bearing 8 Half thrust bearing 11 Journal portion 12 Thrust collar 81 Sliding surface 82 Reverse wedge surface 83 Step surface 84 Oil groove surface

Claims (6)

A bearing device,
A crankshaft of an internal combustion engine;
A pair of half bearings for receiving a radial force of the crankshaft;
A half thrust bearing for receiving an axial force of the crankshaft;
A bearing housing having a holding hole penetratingly formed to hold the pair of half bearings and receiving seats formed on both side surfaces for arranging the half thrust bearing;
In a bearing device having
Among the seats on both side surfaces of the bearing housing, one or two half thrust bearings are provided on the side seats on the side opposite to the side on which the axial force of the crankshaft is input. Each has a sliding surface for supporting the crankshaft in the axial direction and a reverse wedge surface formed so that the wall thickness becomes thinner toward the rotation direction of the crankshaft on one side surface. One or two half thrust bearings are arranged,
Among the seats on both side surfaces of the bearing housing, one or two half thrust bearings are provided on the side seats on the side where the axial force of the crankshaft is input. One or two of the sliding surfaces for supporting the crankshaft in the axial direction and a wedge surface formed so that the wall thickness increases toward the rotation direction of the crankshaft. A bearing device in which a half thrust bearing is arranged. The bearing device according to claim 1, wherein each of the half thrust bearings includes at least three reverse wedge surfaces or wedge surfaces . An oil groove surface for supplying lubricating oil is formed between the reverse wedge surface on the thin wall side or the circumferential end of the wedge surface and the sliding surface. Item 3. The bearing device according to Item 2. The bearing device according to claim 1 , wherein a stepped surface is formed between the reverse wedge surface on the side where the wall thickness is thin or an end portion in the circumferential direction of the wedge surface and the sliding surface. The bearing device according to any one of claims 1 to 4, wherein a depth of the reverse wedge surface or the wedge surface from the sliding surface is 0.005 mm to 0.075 mm. The bearing device according to any one of claims 1 to 5, wherein a circumferential angle defining a circumferential direction of the reverse wedge surface or the wedge surface is set to 5 ° to 35 °.