JP7627170B2 - Engine bearing metal - Google Patents

Description

This disclosure relates to bearing metals for engines, and in particular to bearing metals that support piston pins, crank pins, crank journals, and the like that are equipped in engines.

The engine body (engine frame) is formed with a through hole in which the crankshaft is installed. A bearing metal (slide bearing) is installed on the inner circumferential surface of this through hole, and the crank journal (main journal) that constitutes the crankshaft is slidably supported by the bearing metal installed in this through hole. On the other hand, the small end and big end of the connecting rod also have through holes on their inner circumferential surfaces in which bearing metal is installed. The big end of the connecting rod is connected to the crankshaft by installing the crank pin that constitutes the crankshaft in the through hole of the big end via the bearing metal. The small end of the connecting rod is attached to the piston by the piston pin via the bearing metal installed on the inner circumferential surface of the through hole of the small end.

The bending rigidity of various shafts in engines, such as the crank journals, crank pins, and piston pins mentioned above, has become relatively low in the current trend toward lighter engines and higher power output. As a result, compared to the past, bearings are more prone to problems such as (1) localized high pressure on the bearing surface (bearing surface pressure), (2) increased uneven contact with the bearing end, and (3) a decrease in oil film thickness due to an increase in lubricating oil temperature. When these problems occur, they can cause wear, seizure, fatigue failure, and other problems on the bearing surface, preventing further weight reduction, higher power output, and longer life for engines.

As a countermeasure against this, for example, Patent Document 1 discloses that crowning is formed on the axial ends (both ends) of the sliding surface of the bearing metal (slide bearing) that supports the crankshaft. Patent Document 2 discloses that the sliding surface where the small end and the piston pin slide is coated with a fluororesin as an elastic lubricant to prevent the piston from tilting in the cylinder. Patent Document 3 discloses that the amount of lubricating oil is increased by providing multiple recesses in a specific area of the inner circumferential surface of the pin hole, thereby preventing seizure at the small end. Patent Document 4 discloses that a three-dimensional mesh structure (lattice structure) is formed on the wall surface of the small end to increase the surface area and improve heat dissipation and oil retention. Patent Document 5 discloses a part having the above-mentioned lattice structure.

International Publication No. 2008/072548 JP 2007-40137 A JP 2018-9634 A JP 2018-168895 A JP 2015-93461 A

As a countermeasure against the localized increase in bearing surface pressure, various materials have been developed to increase the strength of the bearing metal material, but this leads to the problem of increasing material costs. As a countermeasure against the increase in the degree of uneven contact with the bearing end, crowning or tapering the ends (both ends) of the bearing metal, as in Patent Document 1, is considered. However, since the area of the parallel part (part not machined) of the bearing metal is reduced by the amount of the machined area, the bearing surface pressure increases and this can be a factor in fatigue failure of the bearing metal. Furthermore, in the case of an engine that operates under various loads, when the amount of deformation on the shaft side is not constant, it is difficult to appropriately prevent the uneven contact described above according to the various engine loads using a method of performing processing such as crowning in advance.

It is also possible to make the underside of the bearing metal (the member forming the through hole) flexible by making it thin-walled or notched, but it may be difficult to achieve the desired flexible structure due to the constraints of stress concentration in the thin-walled or notched parts. Alternatively, it is possible to make the back surface (main body) of the bearing metal's sliding surface against the shaft flexible by making it notched. However, there are concerns that the effective bearing area will be reduced due to the notched part warping during metal crush (tight fit of the bearing metal) when the bearing metal is fitted into the through hole, that the stability of the bearing metal installation will be reduced due to the reduced contact area between the bearing metal and the member forming the through hole, and that this reduced stability will cause fretting at the contact surface.

One possible solution to the decrease in oil film thickness caused by rising lubricating oil temperature is to increase the bearing clearance and lubricating oil flow rate to remove heat. However, increasing the bearing clearance is detrimental to oil film formation, which can lead to an increase in maximum oil film pressure and a decrease in oil film thickness.
Furthermore, oil grooves may be formed to supply lubricating oil to the bearing surface, but cavitation erosion may occur at the ends of the oil grooves, which may shorten the bearing life and damage the bearing surface due to debris generated by cavitation erosion.

In view of the above circumstances, the present disclosure aims to provide a bearing metal that can prevent localized high surface pressure on the bearing surface of bearings that support shafts such as piston pins, crank pins, and crank journals, as well as increased uneven contact at the bearing ends and a decrease in oil film thickness due to an increase in lubricating oil temperature.

One aspect of the engine bearing metal according to the present disclosure is a bearing metal for connecting a connecting rod to a shaft, which is a piston pin, installed in a through hole formed in the small end of the connecting rod so that the connecting rod can swing, the bearing metal comprising: a main body portion installed on the inner circumferential surface of the through hole; and a bearing layer formed on the inner circumferential side of the main body portion, the bearing layer having a sliding surface configured to be slidable against the shaft, the main body portion including a lattice structure portion formed in at least a part of the main body portion, and the lattice structure portion configured to receive lubricating oil from a lubricating oil passage formed inside the connecting rod.

One aspect of the bearing metal according to the present disclosure is a bearing metal for rotatably connecting a connecting rod to an axis, which is a crank pin of a crankshaft, installed in a through hole formed in the big end of the connecting rod, the bearing metal comprising: a main body portion installed on the inner circumferential surface of the through hole; and a bearing layer formed on the inner circumferential side of the main body portion, the bearing layer having a sliding surface configured to be slidable against the axis, the main body portion including a lattice structure portion formed in at least a part of the main body portion, and the lattice structure portion configured to receive lubricating oil from a lubricating oil passage formed inside the engine body.

One aspect of the bearing metal according to the present disclosure is a bearing metal for rotatably supporting a shaft, which is a crank journal of a crankshaft, installed in a through hole formed in an engine body, comprising a main body portion installed on the inner circumferential surface of the through hole, and a bearing layer formed on the inner circumferential side of the main body portion, the bearing layer having a sliding surface configured to be slidable against the shaft, the main body portion including a lattice structure portion formed in at least a part of the main body portion, and the lattice structure portion configured to receive lubricating oil from a lubricating oil passage formed inside the engine body.

According to some aspects of the engine bearing metal disclosed herein, when supporting shafts such as piston pins, crank pins, and crank journals, the pressure applied to the sliding surface (bearing surface) of the bearing metal can be made uniform, uneven contact at the bearing end can be prevented, and the oil film thickness on the sliding surface can be maintained by suppressing the temperature rise of the lubricating oil flowing on the sliding surface. Therefore, wear, seizure, fatigue failure, etc. on the sliding surface can be prevented, and further weight reduction, high output, and long life can be achieved for the engine.

FIG. 1 is a front view showing a connecting rod provided with a bearing metal according to an embodiment, with a part cut away; 2 is a side cross-sectional view taken along line AA in FIG. 1, showing a part thereof in an enlarged scale. 2 is a front cross-sectional view of a small end portion of the connecting rod in FIG. 1 , with a portion cut away. FIG. FIG. 1 is a perspective view showing an example of a lattice structure. FIG. 2 is an enlarged cross-sectional front view of a portion B in FIG. 1 . FIG. 3 is a cross-sectional view taken along line CC in FIG. 2. FIG. 7 is a front cross-sectional view corresponding to FIG. 5 , showing a bearing metal according to another embodiment. FIG. 2 is a cross-sectional side view showing a support portion of a crankshaft according to one embodiment. FIG. 2 is a front cross-sectional view showing a cross section of a portion of a bearing metal according to one embodiment. 9 is a cross-sectional view taken along line D-D in FIG. 8 . FIG. 10 is a front cross-sectional view corresponding to FIG. 9 , showing a bearing metal according to another embodiment. FIG. 7 is a cross-sectional view corresponding to FIG. 6 , showing a bearing metal according to another embodiment. This is a cross-sectional view taken along line E-E in FIG.

Below, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.

For example, expressions such as "same," "equal," and "homogeneous" that express a state in which things are equal do not only express a state in which they are strictly equal, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained.

For example, expressions describing shapes such as a square or cylindrical shape do not only refer to shapes such as a square or cylindrical shape in the strict geometric sense, but also to shapes that include uneven parts, chamfered parts, etc., to the extent that the same effect can be obtained.

On the other hand, the expressions "comprise," "include," "have," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

Fig. 1 is a partially cutaway front view of a connecting rod 20 according to one embodiment. Fig. 2 is a side cross-sectional view taken along line A-A in Fig. 1. Fig. 3 is a partially cutaway front cross-sectional view of a small end 22 of the connecting rod 20 shown in Fig. 1. Fig. 4 is a perspective view showing an example of a lattice structure.
A straight line passing through the center of the cross section of the small end 22 or the big end 24 of the connecting rod 20 and extending in the axial direction of the small end 22 or the big end 24 is called a center line CL. A front view is a view in which the center line CL appears dotted, as in FIG. 1, and a side view is a view in which a plane including the center line CL and a straight line extending in the axial direction of the connecting rod 26 of the connecting rod 20 (extending direction of the connecting rod 26), as in FIG. 2. When the bearing metal 10 (10A) according to the embodiment is installed in the piston pin hole 22a, the center line CL of the bearing metal 10 (10A) and the center line CL of the piston pin hole 22a coincide with each other. When the bearing metal 10 (10B) according to the embodiment is installed in the crank pin 32a, the center line CL of the bearing metal 10 (10B) and the center line CL of the crank pin 32a coincide with each other.

As shown in Figures 1 and 2, the connecting rod 20 is a component for converting the reciprocating motion of a piston (not shown) in an engine (internal combustion engine) into the rotational motion of a crankshaft 32. The connecting rod 20 has a small end 22, a big end 24, and a connecting rod 26 that connects the small end 22 and the big end 24. A piston pin 30 (shaft) is connected to the small end 22, and a crankshaft 32 (shaft) (see Figure 7) is connected to the big end 24, thereby connecting the piston (not shown) and the crankshaft 32 via the connecting rod 20.

8, which will be described later, the crankshaft 32 has a crank pin 32a (shaft) that is connected to the big end 24 of the connecting rod 20, and a crank journal 32b (shaft) that is supported by an engine body 40, such as a cylinder block or a crankcase. On the other hand, a main bearing portion 42 formed in the engine body 40 is formed with a main shaft hole 42a (through hole) for attaching the crank journal 32b.
In this specification, the term "engine body" refers to the casing of the engine, also known as the engine frame, crankcase, etc.

(Configuration of the bearing metal 10 (10A) provided at the small end 22 of the connecting rod 20)
As shown in FIG. 3, a bearing metal 10 (10A) according to one embodiment is provided in a piston pin hole 22a (through hole) formed in a small end 22 of a connecting rod 20, and connects a piston pin 30 (shaft) and the connecting rod 20 so as to be able to swing. The bearing metal 10 (10A) includes a main body 12 provided so as to contact the inner peripheral surface of the small end 22 forming the piston pin hole 22a, and a bearing layer 14 formed on the inner peripheral side of the main body 12. The inner peripheral surface 14a of the bearing layer 14 forms a sliding surface that can slide against the outer peripheral surface of the piston pin 30. The main body 12 includes a lattice structure 16 in at least a part of the main body 12. A lubricating oil passage is formed inside the connecting rod 20, and the lattice structure 16 is in communication with this lubricating oil passage, and lubricating oil is supplied to the lattice structure 16 from the lubricating oil passage.

In this specification, "lattice structure" refers to a structure described below. That is, a lattice structure has a three-dimensional grid or mesh structure in which multiple hollow or solid pillars (e.g., cylindrical) are connected in a predetermined connection pattern, and cavities that form continuous spaces are formed between the pillars. The pillars may have a constant cross-sectional area or may have a variable cross-sectional area. By changing the porosity (volume density) of the hollows, the material properties such as rigidity can be adjusted as desired.

Figure 4 is a perspective view showing an example of a lattice structure. As shown in Figure 4, a three-dimensional structure is formed in which multiple hollow or solid pillars 100 are connected in a predetermined connection pattern. Figure 4 shows an example of a minimum unit connection pattern. A cavity ca is formed between the pillars 100. Even if multiple connection patterns are connected, the cavity ca formed in each connection pattern forms a continuous space across the multiple connection patterns. Figure 4 is only one example of a lattice structure, and in other examples, the length, orientation, or number of the pillars 100 is changed, or the cross-sectional shape of the pillars 100 is changed. Since the lattice structure portion 16 has the cavity ca, it has a lower rigidity than the surrounding main body portion 12.

The bearing layer 14 is made of, for example, a soft material to improve sliding properties with respect to the shafts such as the piston pin 30, crank pin 32a, and crank journal 32b.

1 to 3 show an embodiment of the lubricating oil passage formed in the small end portion 22. In FIG. 1 to 3, a lubricating oil passage 50 is formed inside the connecting rod 26 along the axial direction of the connecting rod 26. In addition, a groove 52 is formed in the inner peripheral surface of the small end portion 22 that contacts the outer peripheral surface of the bearing metal 10 (10A) so as to surround the bearing metal 10 (10A) and extend along the circumferential direction of the bearing metal 10 (10A). The groove 52 is connected to the lubricating oil passage 50. Furthermore, a plurality of opening holes 54 are formed that are connected to the groove 52. The plurality of opening holes 54 are distributed along the circumferential direction of the bearing metal 10 (10A), extend radially inward of the bearing metal 10 (10A) so as to intersect with the bearing metal 10 (10A), penetrate the main body portion 12 of the bearing metal 10 (10A) and communicate with the lattice structure portion 16, and further open to the inner peripheral surface 14a of the bearing layer 14. The opening hole 54 communicates with a space formed in a cavity portion ca formed in the lattice structure portion 16. Furthermore, a recessed groove 56 is formed in a region including the opening of the opening hole 54 on the inner circumferential surface 14a.
In one embodiment, the openings 54 formed in the body 12 are filled with the lattice structure 16. However, in another embodiment, the openings 54 formed in the body 12 are not filled with the lattice structure 16.

As shown in FIG. 3, the lubricating oil o flows from the lubricating oil passage 50 through the groove 52 and the opening hole 54 on the outer circumferential side of the lattice structure 16 into the cavity ca of the lattice structure 16. The lubricating oil o that flows into the cavity ca flows through the opening hole 54 on the inner circumferential surface 14a side of the lattice structure 16 and flows from the groove 56 into the inner circumferential surface 14a (sliding surface) to lubricate the inner circumferential surface 14a.

As shown in FIG. 2, inside the main body 12, the lattice structure 16 extends to reach both axial end faces of the small end 22 (extending direction of the center line CL). The lubricating oil flows from the groove 52 through the opening hole 54 into the cavity ca, flows through the cavity ca in the axial direction of the bearing metal 10 (10A) to absorb heat from the main body 12, and then forms two flow paths: one that flows out from both axial end faces of the small end 22, and the other that flows out from the groove 52 through the opening hole 54 into the groove 56 to lubricate the sliding surface (bearing surface; inner circumferential surface 14a of the bearing layer 14) of the bearing metal 10 (10A). The flow rate of each of these two flows is adjusted by the structure of the lattice structure 16 and the porosity of the cavity ca.

With this configuration, the bearing metal 10 (10A) has a lattice structure 16 formed on at least a portion of the main body 12, and the lattice structure 16 has a lower rigidity than the surrounding main body 12, allowing the bearing metal 10 (10A) to elastically deform. This allows the bearing metal 10 (10A) to deform in response to the pressure applied to the sliding surface of the bearing metal 10 (10A) from the piston pin 30 and the uneven contact of the piston pin 30 with both axial ends of the bearing, making it possible to equalize the pressure applied to the sliding surface and suppress uneven contact with the bearing metal 10 (10A).

In the embodiment shown in FIG. 2, the lattice structure 16 extends to both axial end faces of the small end 22, so that the elastic deformation of the lattice structure 16 that reaches both end faces can effectively prevent the piston pin 30 from hitting one side.

The lattice structure 16 also forms a continuous cavity ca inside, and lubricating oil is supplied to the lattice structure 16 from the lubricating oil passage 50 formed in the connecting rod 20, forming a lubricating oil flow path in the cavity ca. In this way, the bearing metal 10 (10A) can be cooled by the lubricating oil steadily flowing through the cavity ca, so that the temperature rise of the bearing metal 10 (10A) can be suppressed, and at the same time, the temperature rise of the lubricating oil flowing on the sliding surface 14a can be suppressed, so the oil film thickness on the sliding surface 14a can be maintained.

This eliminates the need to widen the bearing clearance for the piston pin hole 22a to increase the amount of lubricating oil and provide a cooling function, as in the past, and allows the bearing clearance to be set to an optimal clearance for the bearing oil film characteristics. Also, the initial value of the bearing clearance can be narrowed, which results in an increase in the allowable amount of wear of the bearing and an extension of the bearing life.
Furthermore, since the lattice structure 16 can be manufactured using a three-dimensional modeling device such as a 3D printer, it can be manufactured with any stiffness distribution according to the expected bearing surface pressure and one-sided contact state. This makes it possible to realize a bearing metal that is both strong and flexible.
As a result, wear, seizure, fatigue damage, and the like of the sliding surface 14a (bearing surface) can be prevented, and further weight reduction, higher output, and longer life of the engine can be achieved.

In the above embodiment, the lattice structure 16 provided on the bearing metal 10 (10A) is provided over the entire axial area of the small end 22 and the entire circumferential area of the sliding surface 14a, but in another embodiment, it may be provided over a portion of the axial area of the small end 22 or a portion of the circumferential area of the sliding surface 14a.

In the above embodiment, as shown in FIG. 2, the lattice structure 16 is contained within the main body 12 except for both axial end faces of the small end 22. On the other hand, in another embodiment, the main body 12 between the inner circumferential surface of the piston pin hole 22a and the lattice structure 16 may be eliminated, and the inner circumferential surface of the piston pin hole 22a and the lattice structure 16 may be configured to be in direct contact with each other.

In one embodiment, as shown in FIG. 1, the lattice structure 16 is provided in a region (e.g., region R1 shown in FIG. 1) that is located toward the big end in the axial direction of the connecting rod 20 from the center line CL that passes through the cross-sectional center of the piston pin hole 22a and extends in the axial direction of the small end 22. Region R1 is a portion of the main body 12 of the bearing metal 10 (10A) where the piston pin 30 makes a large one-sided contact and is prone to one-sided contact. That is, the one-sided contact with the piston pin 30 is greater on the connecting rod 26 side of the piston pin hole 22a than on the opposite side. In this way, by forming the lattice structure 16 in a portion where one-sided contact is likely to occur, the effect of equalizing the bearing surface pressure and the effect of suppressing one-sided contact can be effectively achieved.

(Configuration of the bearing metal 10 (10B) provided at the big end 24 of the connecting rod 20)
Fig. 5 is an enlarged view (front cross-sectional view) of part B in Fig. 1, and Fig. 6 is a cross-sectional view taken along line CC in Fig. 2. As shown in Fig. 1, a bearing metal 10 (10B) according to one embodiment is a bearing metal for rotatably connecting a crankshaft 32 installed in a crankpin hole 24a (through hole) formed in a big end 24 of a connecting rod 20, as described below, to a connecting rod.

As shown in Figs. 5 and 6, the bearing metal 10 (10B) includes a main body 12 provided to contact the inner peripheral surface of the big end 24 that forms the crankpin hole 24a, and a bearing layer 14 formed on the inner peripheral side of the main body 12. The inner peripheral surface 14a of the bearing layer 14 forms a sliding surface that can slide against the outer peripheral surface of the crankpin 32a. The main body 12 includes at least a lattice structure 16. As shown in Fig. 8, which will be described later, a lubricating oil passage 70 is formed in the engine body 40, and the lubricating oil o supplied from the lubricating oil passage 70 is supplied to the cavity ca formed inside the lattice structure 16 through the lubricating oil passage formed in the crankpin 32a, etc., and the recessed groove 64 formed in the inner peripheral surface 14a, as will be described later.

The lubricating oil passage formed in the big end 24 has a groove 60 formed along the circumferential direction of the bearing metal 10 (10B) so as to surround the bearing metal 10 (10B) on the inner peripheral surface 24a of the big end 24 that contacts the outer peripheral surface of the bearing metal 10 (10B). The groove 60 is connected to the lubricating oil passage 50 formed in the connecting rod 26. In addition, a plurality of opening holes 62 are formed that communicate with the groove 60, and the plurality of opening holes 62 are distributed along the circumferential direction of the bearing metal 10 (10B), extend in the radial direction of the bearing metal 10 (10B) so as to intersect with the bearing metal 10 (10B), penetrate the main body portion 12 of the bearing metal 10 (10B) and communicate with the lattice structure portion 16, and further open to the inner peripheral surface 14a of the bearing layer 14. The opening holes 62 are connected to a space formed in a cavity portion ca formed in the lattice structure portion 16. Furthermore, a recessed groove 64 is formed in the inner circumferential surface 14a, and the opening hole 62 opens in the region of the inner circumferential surface 14a where the recessed groove 64 is formed.
5, the openings 62 formed in the body 12 are filled with the lattice structure 16. On the other hand, in another embodiment, the openings 62 formed in the body 12 are not filled with the lattice structure 16.

As shown in FIG. 6, inside the main body 12, the lattice structure 16 extends until it reaches both end faces of the big end 24 in the axial direction (extension direction of the center line CL). The lubricating oil o flows from the lubricating oil passage 70 through the lubricating oil passage described later into the groove 64. The lubricating oil o then forms two flow paths: one for lubricating the sliding surface (bearing surface, inner surface 14a of the bearing layer 14) of the bearing metal 10 (10B), and the other for flowing from the groove 64 through the opening hole 62 into the cavity ca of the lattice structure 16, flowing in the axial direction of the bearing metal 10 (10B) in the cavity ca to absorb heat from the main body 12, and then flowing out from both axial end faces of the big end 24. The flow rate of each of these two flows is adjusted by the structure of the lattice structure 16 and the porosity of the cavity ca.

According to this configuration, the bearing metal 10 (10B) has a lattice structure 16 formed on at least a part of the main body 12, and the lattice structure 16 has a lower rigidity than the surrounding part of the main body 12, so that the bearing metal 10 (10B) can be elastically deformed. As a result, the bearing metal 10 (10B) can deform in response to the bearing surface pressure received from the crank pin 32a and the uneven contact of the crank pin 32a with the bearing end, so that the bearing surface pressure can be made uniform and uneven contact can be suppressed. Furthermore, by supplying lubricating oil to the continuous cavity ca formed in the lattice structure 16, a lubricating oil passage can be formed in the cavity ca, and the cooling effect of the bearing metal 10 (10B) can be improved. In addition, the same action and effect as the bearing metal 10 (10A) described above can be obtained.

In the embodiment shown in FIG. 6, the lattice structure 16 extends to both axial end faces of the big end 24, so that the elastic deformation of the lattice structure 16 that reaches both end faces can effectively prevent the crank pin 32a from hitting one side.

In this embodiment, the lattice structure 16 provided on the bearing metal 10 (10B) is provided over the entire axial area of the big end 24 and the entire circumferential area of the sliding surface 14a, but in other embodiments, it may be provided over only a portion of the axial area of the big end 24 or a portion of the circumferential area of the sliding surface 14a.

In the above embodiment, as shown in FIG. 6, the lattice structure 16 is contained within the main body 12, except for both axial end faces of the big end 24. However, in another embodiment, the main body 12 between the inner circumferential surface of the crank pin 32a and the lattice structure 16 may be eliminated, and the inner circumferential surface of the crank pin 32a and the lattice structure 16 may be configured to be in direct contact with each other.

Figure 7 shows another embodiment of the bearing metal 10 (10B). In this embodiment, the bearing metal 10 (10B) is formed in two pieces, and a pair of semicircular bearing metal pieces are assembled by contacting the mating surfaces 25. In this embodiment, as shown in Figure 7, the lattice structure portion 16 does not extend to the mating surfaces 25 in the circumferential direction of the bearing metal 10 (10B). Therefore, when the pair of bearing metal pieces are assembled by contacting the mating surfaces 25, stable assembly is possible.

In one embodiment, the lattice structure portion 16 of the bearing metal 10 (10B) is provided toward the small end 22 in the axial direction of the connecting rod 20, from the center line CL that passes through the cross-sectional center of the crankpin hole 24a of the big end 24, for example, in the region R2 in FIG. 1.
In the big end 24, the crank pin 32a makes large one-sided contact with the big end 24 in region R2, and therefore one-sided contact is likely to occur in the above region. By forming the lattice structure portion 16 in this manner in the area where one-sided contact is likely to occur, it is possible to effectively achieve the effects of equalizing the bearing surface pressure and suppressing one-sided contact.

(Configuration of the bearing metal 10 (10C) provided on the crank journal)
Fig. 8 is a side cross-sectional view showing a support portion of the crankshaft 32. Fig. 9 is a front cross-sectional view showing an enlarged portion of the bearing metal 10 (10C). Fig. 10 is a cross-sectional view taken along line D-D in Fig. 8.

As shown in FIG. 8, the bearing metal 10 (10C) according to one embodiment is a bearing metal for rotatably supporting the crank journal 32b (shaft) of the crankshaft 32 installed in the main shaft hole 42a (through hole) formed in the main bearing portion 42 of the engine body 40. The crank journal 32b is inserted into the main shaft hole 42a in which the bearing metal 10 (10C) is installed, thereby supporting the crankshaft 32 on the engine body 40.

As shown in FIG. 9, the bearing metal 10 (10C) comprises a main body 12 installed on the inner circumferential surface of the main shaft hole 42a and a bearing layer 14 formed on the inner circumferential side of the main body 12, and the inner circumferential surface 14a of the bearing layer 14 forms a sliding surface that can slide against the crank journal 32b. A lattice structure 16 is formed on at least a part of the main body 12, and lubricating oil can be supplied to the cavity ca of the lattice structure 16 from a lubricating oil passage 70 formed inside the engine body 40.

A groove 72 is formed in the circumferential direction of the bearing metal 10 (10C) surrounding the bearing metal 10 (10C) on the inner peripheral surface of the main bearing portion 42 that contacts the outer peripheral surface of the bearing metal 10 (10C), and the groove 72 is connected to the lubricating oil passage 70. In addition, a plurality of opening holes 74 are formed that are distributed along the circumferential direction of the bearing metal 10 (10C) and communicate with the groove 72. Each of the plurality of opening holes 74 extends in the radial direction of the bearing metal 10 (10C) so as to intersect with the bearing metal 10 (10C), penetrates the main body portion 12, communicates with the lattice structure portion 16, and further opens to the inner peripheral surface 14a of the bearing layer 14. The opening hole 74 is connected to a space formed in a cavity portion ca formed in the lattice structure portion 16.
9, the openings 74 formed in the body 12 are filled with the lattice structure 16. On the other hand, in another embodiment, the openings 74 formed in the body 12 are not filled with the lattice structure 16.
Furthermore, as shown in FIG. 10 , a groove 76 extending circumferentially of the inner circumferential surface 14a of the bearing layer 14 is formed, and the opening hole 74 opens within the region of the sliding surface 14a in which the groove 76 is formed.

As shown in FIG. 9, the lubricating oil o supplied from the lubricating oil passage 70 flows into the cavity ca of the lattice structure portion 16 through the groove 72 and the opening hole 74 on the outer periphery side of the lattice structure portion 16. After flowing into the cavity ca, the lubricating oil o circulates around the cavity ca, then flows out of the opening hole 74 on the inner periphery side of the lattice structure portion 16, and flows out of the groove 76 onto the sliding surface 14a, lubricating the sliding surface 14a.

As shown in FIG. 10, inside the main body 12, the lattice structure 16 extends until it reaches both end faces of the axial direction (extension direction of the center line CL) of the main bearing 42. The lubricating oil o supplied from the lubricating oil passage 70 flows from the groove 72 through the opening hole 74 into the cavity ca. After that, the lubricating oil o flows in the axial direction of the bearing metal 10 (10C) in the cavity ca to absorb the heat of the main body 12, and then forms two flow paths: one that flows out from both axial end faces of the main bearing 42, and one that flows out from the cavity ca to the groove 76 to lubricate the sliding surface (bearing surface; inner peripheral surface 14a of the bearing layer 14) of the bearing metal 10 (10C). The flow rate of each of these two flows is adjusted by the structure of the lattice structure 16 and the porosity of the cavity ca.

The flow path of the lubricating oil o supplied to the bearing metal 10 (10A-10C) will be described below as one embodiment. As shown in FIG. 8, the lubricating oil o that has reached the groove 76 from the lubricating oil passage 70 through the bearing metal 10 (10C) flows from the groove 76 into the lubricating oil passage 80 formed in the main bearing portion 42. Inside the crank pin 32a, a lubricating oil passage 82 is formed, one end of which is connected to the lubricating oil passage 80, and a lubricating oil passage 84 is formed, one end of which is connected to the lubricating oil passage 82 and the other end of which is connected to the groove 64. The lubricating oil o travels from the lubricating oil passage 80 through the lubricating oil passages 82, 84 and the groove 64 to reach the lattice structure portion 16 of the bearing metal 10 (10B) provided in the big end 24. Furthermore, as shown in FIG. 5, the flow path is divided into a flow path that is supplied from the cavity ca of the lattice structure 16 of the bearing metal 10 (10B) to the inner circumferential surface 14a (sliding surface) of the bearing layer 14, and a flow path that flows into the lubricating oil passage 50 formed in the connecting rod 26 through the opening hole 62 and the groove 60. The lubricating oil o that flows into the lubricating oil passage 50 is supplied to the sliding surface (bearing surface) 14a of the bearing metal 10 (10A) through the groove 52, the opening hole 54, and the groove 56 as described above.

According to this embodiment, the bearing metal 10 (10C) has a lattice structure 16 formed on at least a part of the main body 12, and the lattice structure 16 has a lower rigidity than the surrounding main body 12, so that the bearing metal 10 (10C) can be elastically deformed. As a result, the bearing metal 10 (10C) can deform in response to the bearing surface pressure received from the crankshaft 32 and the uneven contact at the bearing end by the crankshaft 32, so that the bearing surface pressure can be made uniform and uneven contact can be suppressed. Furthermore, by supplying lubricating oil to the cavity ca formed in the lattice structure 16, the cooling effect of the lubricating oil can be improved. In addition, the same effects as those of the above-mentioned bearing metal 10 (10A, 10B) can be obtained.

In the embodiment shown in Figures 8 to 10, the lattice structure 16 of the bearing metal 10 (10C) extends to both axial end faces of the main bearing portion 42, so that the elastic deformation ability of the lattice structure 16 that reaches both end faces can effectively suppress uneven contact of the crank journal 32b.

In this embodiment, the lattice structure 16 provided on the bearing metal 10 (10C) is provided over the entire axial area of the crank journal 32b and the entire circumferential area of the sliding surface 14a, but in other embodiments, it may be provided over a portion of the axial area of the crank journal 32b or a portion of the circumferential area of the sliding surface 14a.

In the above embodiment, as shown in FIG. 10, the lattice structure 16 is contained within the body 12 except for both axial end surfaces of the main bearing 42. However, in another embodiment, the body 12 between the inner peripheral surface of the main bearing 42 that forms the main shaft hole 42a and the lattice structure 16 may be eliminated, and the inner peripheral surface of the main bearing 42 and the lattice structure 16 may be in direct contact with each other.

In one embodiment, the lattice structure 16 is provided in a region located below the center line CL passing through the cross-sectional center of the through hole 14a on the engine body 40. For example, as shown in FIG. 8, it is provided in regions R3 and R4. That is, regions R3 and R4 are areas where uneven contact of the crank journal 32b is large and uneven contact is likely to occur, and the lattice structure 16 is formed in the area where such uneven contact is likely to occur. In this way, by forming the lattice structure 16 in the area where uneven contact is likely to occur, it is possible to effectively achieve the effects of equalizing the bearing surface pressure and suppressing uneven contact.

Also, like regions R3 and R4, the lattice structure 16 may be formed on both axial end sides of the bearing metal 10 (10C), or on at least one end side. That is, the lattice structure 16 is provided in an area of the sliding surface 14a of the bearing metal 10 (10C) that receives partial contact with the crank journal 32b.
When the lattice structure portion 16 is provided in a portion where the crank journal 32b is likely to make one-sided contact in this manner, the lattice structure portion 16 elastically deforms in the direction of the one-sided contact caused by the bending of the crank journal 32b, according to the magnitude of the one-sided contact. That is, as shown in Fig. 8, the lattice structure portion 16 elastically deforms in response to the bending of the crank journal 32b (dash line). The sliding surface 14a also elastically deforms in response to the elastic deformation of the lattice structure portion 16. This makes it possible to prevent the occurrence of regions where the oil film pressure on the sliding surface 14a becomes locally high or the oil film thickness becomes locally thin, due to the one-sided contact of the crank journal 32b.

In addition, in the bearing metal 10 (10C), the areas where the uneven contact is large differ depending on the type of engine. Therefore, in another embodiment, the areas where the uneven contact is large depending on the type of engine are predicted by calculation, and the lattice structure portion 16 is provided in the predicted areas.

Figure 11 shows another embodiment of the bearing metal 10 (10C). In this embodiment, the bearing metal 10 (10C) is formed in two pieces, and a pair of semicircular bearing metal pieces are assembled by contacting the mating surfaces 25. In this embodiment, as shown in Figure 11, the lattice structure 16 does not extend to the mating surfaces 25. Therefore, when the pair of bearing metal pieces are assembled by contacting the mating surfaces 25, stable assembly is possible.

Fig. 12 relates to yet another embodiment and is a cross-sectional view corresponding to Fig. 6. Fig. 13 is a cross-sectional view taken along line EE in Fig. 12.
In this embodiment, in the bearing metal 10 (10B) provided on the inner peripheral surface 14a of the big end 24, a groove 64 is formed in the inner peripheral surface 14a of the bearing layer 14, and further, in the inner region of the groove 64, a notch 14b is formed in which the bearing layer 14 is removed to expose the lattice structure portion 16. The notch 14b exposes the lattice structure portion 16 on the inner peripheral side. The lubricating oil o is supplied to the sliding surface 14a from the lubricating oil passage 70 through the above-mentioned lubricating oil passages 80, 82, and 84, and is further supplied from the groove 64 through the notch 14b to the cavity portion ca of the lattice structure portion 16. A part of the lubricating oil o supplied to the cavity portion ca flows out from both axial end faces of the bearing metal 10 (10B), and a part flows out into the groove 60.

The lattice structure portion 16 has a first lattice structure portion 16 (16a) having a first porosity P1 and a second lattice structure portion 16 (16b) having a second porosity P2 larger than the first porosity P1. The second lattice structure portion 16 (16b) is disposed to face the cutout portion 14b and is exposed on the inner peripheral side.

In the embodiment shown in Fig. 13, the bearing layer 14 is formed on the bottom surface of the groove 64 excluding the cutout portion 14b (region R5 shown in Fig. 13). The bearing layer 14 is formed to a constant thickness. On the other hand, in another embodiment, the bearing layer 14 may not be formed on the bottom surface of the groove 64, and the main body portion 12 may be exposed to the inner periphery.
In the embodiment shown in FIG. 13, the cross section of the groove 64 has an arc shape whose bottom surface smoothly becomes deeper toward the lattice structure portion 16 (16b).

In this way, the second lattice structure portion 16 (16b) having a large porosity is arranged facing the cutout portion 14b, so the amount of lubricating oil flowing from the sliding surface 14a to the second lattice structure portion 16 (16b) can be increased. Therefore, the amount of lubricating oil flowing on the sliding surface (bearing surface) 14a of the bearing metal 10 (10B) can be increased, so that the temperature rise of the lubricating oil o flowing on the sliding surface 14a can be suppressed and the oil film thickness on the sliding surface 14a can be effectively maintained.

Furthermore, by adjusting the size and shape of the notch 14b or the porosity of the second lattice structure portion 16 (16b) exposed from the notch 14b, the amount of lubricating oil o flowing into the groove 64 can be adjusted, improving the cooling effect of the bearing metal 10 (10B) and suppressing cavitation that occurs around the groove 64. This makes it possible to prevent seizure and extend the life of the sliding surface 14a of the bearing metal 10 (10B).

In the embodiment shown in FIG. 13, the arrangement area of the notch 14b coincides with the arrangement area of the second lattice structure portion 16 (16b), so that the amount of lubricating oil flowing from the sliding surface 14a to the second lattice structure portion 16 (16b) can be increased and the effect of suppressing cavitation around the groove 64 can be further improved.

The above embodiment is an embodiment in which the notch 14b is provided in the bearing metal 10 (10B), but it goes without saying that this embodiment can also be applied to the bearing metal 10 (10A, 10C).

Regarding each embodiment shown in Figures 1 to 11, the through holes such as the piston pin hole 22a, the crank pin hole 24a, and the crank journal 32b have a cylindrical shape that has a perfectly circular cross section. The engine is a multi-cylinder engine, and the crankshaft 32 has multiple crank pins 32a and multiple crank journals 32b. It is also a V-type engine, and each crank pin 32a is connected to two connecting rods 20 that are connected to pistons (not shown) in each cylinder of each bank of the V.

In each embodiment shown in Figures 1 to 11, the small end 22 and the connecting rod 26 are integrally manufactured (formed), and the connecting rod 26 and the big end 24 are configured to be fastened with a bolt 90, but at least two of the big end 24, the small end 22, and the connecting rod 26 may be integrally manufactured.

The bearing metal according to the present disclosure is not limited to the above-mentioned embodiment, but also includes modifications to the above-mentioned embodiment and appropriate combinations of these embodiments.

The contents described in each of the above embodiments can be understood, for example, as follows:

1) In one embodiment, the engine bearing metal (10) is a bearing metal (10 (10A)) for connecting a connecting rod (20) to an axis, which is a piston pin (30) installed in a through hole (22a) formed in the small end (22) of the connecting rod (20) so that the connecting rod (20) can swing, and includes a main body (12) installed on the inner peripheral surface of the through hole (22a) and a bearing layer (14) formed on the inner peripheral side of the main body (12) and having a sliding surface (14a) configured to be slidable against the axis, the main body (12) includes a lattice structure (16) formed in at least a part of the main body (12), and the lattice structure (16) is configured to be supplied with lubricating oil (o) from a lubricating oil passage (50) formed inside the connecting rod (20).

With this configuration, the lattice structure has a lower rigidity than the surrounding area of the main body, allowing the bearing metal to deform elastically. This allows the bearing metal to deform in response to the pressure applied from the piston pin (shaft) to the sliding surface (bearing surface) of the bearing metal and the uneven contact of the piston pin with the bearing end, making it possible to equalize the pressure applied to the sliding surface and suppress uneven contact with the bearing metal.

In addition, the lattice structure has a continuous cavity formed therein, and the lubricating oil is supplied to this cavity from the lubricating oil passage formed inside the connecting rod, forming a lubricating oil flow path through which the lubricating oil flows, so that the bearing metal can be cooled by the lubricating oil flowing through the cavity. This makes it possible to suppress a rise in temperature of the bearing metal, and at the same time, to suppress a rise in temperature of the lubricating oil flowing on the sliding surface of the bearing metal, thereby maintaining the oil film thickness on the sliding surface.
In addition, since it is no longer necessary to widen the bearing clearance to increase the amount of lubricating oil and provide a cooling function as in the past, the bearing clearance can be set to an optimal clearance for the bearing oil film characteristics.In addition, since the initial value of the bearing clearance can be narrowed, the allowable amount of wear of the bearing is increased as a result, and the bearing life can be extended.

Furthermore, because the lattice structure can be manufactured using a three-dimensional modeling device such as a 3D printer, it can be manufactured with any stiffness distribution according to the expected bearing surface pressure and one-sided contact state. This makes it possible to realize a bearing metal that is both strong and flexible.
As described above, according to one embodiment of the bearing metal of the present disclosure, wear, seizure, fatigue failure, etc. of the sliding surface (bearing surface) can be prevented, thereby achieving further weight reduction, higher output, and longer life of the engine.

2) Another embodiment of the bearing metal (10) is the bearing metal (10 (10A)) described in 1), in which the lattice structure portion (16) is disposed toward the big end (24) side in the axial direction of the connecting rod (20) from the center line (CL) passing through the cross-sectional center of the through hole (22a).

With this configuration, the lattice structure is provided in areas where uneven contact is likely to occur, such as areas where the piston pin makes large uneven contact with the bearing metal. In other words, the uneven contact of the piston pin (shaft) is greater on the large end side of the through hole at the small end than on the opposite side. Therefore, by forming a lattice structure in an area where uneven contact is likely to occur, it is possible to effectively achieve the effects of equalizing the bearing surface pressure and suppressing uneven contact.

3) A bearing metal (10) according to yet another embodiment is a bearing metal (10 (10B)) for rotatably connecting an axis, which is a crank pin (32a) of a crankshaft (32) installed in a through hole (24a) formed in the big end (24) of a connecting rod (20), to the connecting rod (20), and includes a main body portion (12) installed on the inner peripheral surface of the through hole (24a), and a bearing layer (14) formed on the inner peripheral side of the main body portion (!2), the bearing layer having a sliding surface (14a) configured to be slidable against the axis, the main body portion (12) includes a lattice structure portion (16) formed in at least a part of the main body portion (12), and the lattice structure portion (16) is configured to be supplied with lubricating oil (o) from a lubricating oil passage (70) formed inside the engine body (40).

With this configuration, the lattice structure has a lower rigidity than the surrounding portion of the main body, allowing the bearing metal to elastically deform. This allows the bearing metal to deform in response to the bearing surface pressure received from the crank pin (shaft) and uneven contact at the bearing end by the crank pin, making it possible to equalize the bearing surface pressure and suppress uneven contact. Furthermore, by supplying lubricating oil to the continuous hollow portions of the lattice structure, a lubricating oil passage can be formed in the hollow portions, thereby enhancing the cooling effect of the bearing metal. In addition, the same action and effect can be obtained as with the bearing metal having the configuration of (1).

4) A further embodiment of the bearing metal is the bearing metal (10 (10B)) described in 3), in which the lattice structure portion (16) is disposed toward the small end portion (22) of the connecting rod (20) in the axial direction, away from the center line (CL) passing through the center of the cross section of the through hole (24a).

With this configuration, the lattice structure is provided in areas where uneven contact is likely to occur, such as areas where the crank pin makes large uneven contact with the bearing metal, i.e., toward the small end in the axial direction of the connecting rod. In this way, by forming the lattice structure in areas where uneven contact is likely to occur, it is possible to effectively achieve the effects of equalizing the bearing surface pressure and suppressing uneven contact.

5) A bearing metal (10) according to yet another embodiment is a bearing metal (10 (10C)) for rotatably supporting an axis, which is a crank journal (32b) of a crankshaft (32) installed in a through hole (42a) formed in an engine body (40), and includes a main body portion (12) installed on the inner peripheral surface of the through hole (42a), and a bearing layer (14) formed on the inner peripheral side of the main body portion (12), the bearing layer having a sliding surface (14a) configured to be slidable against the axis, the main body portion (12) includes a lattice structure portion (16) formed on at least a part of the main body portion (12), and the lattice structure portion (16) is configured to be supplied with lubricating oil (o) from a lubricating oil passage (70) formed inside the engine body (40).

With this configuration, the lattice structure has a lower rigidity than the surrounding portion inside the main body, allowing the bearing metal to elastically deform. This allows the bearing metal to deform in response to the bearing surface pressure received from the crankshaft (axis) and uneven contact at the bearing end by the crankshaft, making it possible to equalize the bearing surface pressure and suppress uneven contact. Furthermore, by supplying lubricating oil to the hollow portion of the lattice structure, the cooling effect of the lubricating oil can be improved. In addition, the same effects as those of the bearing metal having the configuration of (1) or (3) can be obtained.

6) A further embodiment of the bearing metal (10) is the bearing metal (10 (10C)) described in 5), in which the lattice structure portion (16) is provided below the center line (CL) passing through the cross-sectional center of the through hole (42a) on the engine body (40).

According to this configuration, the lattice structure is provided on the lower side of the crankcase from the center line passing through the cross-sectional center of the through hole in the part where uneven contact is likely to occur, such as the part where the crank journal (shaft) is in large uneven contact in the main body of the bearing metal installed in the through hole formed in the crankcase. In this way, by forming the lattice structure in the part where uneven contact is likely to occur, it is possible to effectively achieve the effect of equalizing the bearing surface pressure and the effect of suppressing uneven contact.

7) A further embodiment of the bearing metal (10) is the bearing metal (10) according to any one of 1) to 6), in which the bearing layer (14) has a notch (14b) through which the lattice structure portion (16) is exposed on the inner periphery side, the lattice structure portion (16) includes a first lattice structure portion (16 (16a)) having a first porosity (P1) and a second lattice structure portion (16 (16b)) having a second porosity (P2) greater than the first porosity (P1), and the second lattice structure portion (16 (16b)) is arranged facing the notch (14b) and is configured to be exposed on the inner periphery side.

With this configuration, the second lattice structure portion with a large porosity is disposed facing the notch portion, so the amount of lubricating oil flowing on the bearing surface of the bearing metal can be increased. This increases the cooling effect of the bearing metal and also suppresses the rise in temperature of the lubricating oil flowing on the sliding surface (bearing surface) of the bearing metal, so the oil film thickness on the sliding surface can be maintained. In addition, by adjusting the shape or size of the notch portion or the porosity of the second lattice structure portion, the amount of lubricating oil flowing into the groove can be adjusted, so the cooling effect of the bearing metal can be improved and cavitation that occurs around the groove can be suppressed. This makes it possible to prevent seizure on the sliding surface of the bearing metal and to achieve a longer life.

10 (10A, 10B, 10C) Bearing metal 12 Body portion 14 Bearing layer 14a Inner peripheral surface (sliding surface)
14b Cutout portion 16 Lattice structure portion 16 (16a) First lattice structure portion 16 (16b) Second lattice structure portion 20 Connecting rod 22 Small end portion 22a Piston pin hole 24 Big end portion 24a Crank pin hole 25 Mating surface 26 Connecting rod 30 Piston pin (shaft)
32 Crankshaft 32a Crankpin (shaft)
32b Crank journal (shaft)
Reference Signs List 40 Engine body 42 Main bearing portion 42a Main shaft hole 50, 70, 80, 82, 84 Lubricating oil passage 52, 56, 60, 64, 72, 76 Groove 54, 62, 74 Opening hole 90 Bolt 100 Columnar body CL Center line P1 First porosity P2 Second porosity R1, R2, R3, R4 Region where lattice structure portion 16 is arranged ca Cavity o Lubricating oil

Claims (6)

A bearing metal for connecting a connecting rod to a shaft, which is a piston pin, in a through hole formed in a small end of the connecting rod so as to be able to swing,
A main body portion is installed on an inner circumferential surface of the through hole;
a bearing layer formed on an inner circumferential side of the main body, the bearing layer having a sliding surface configured to be slidable relative to the shaft;
Equipped with
the body portion includes a lattice structure formed on at least a portion of the body portion;
The lattice structure is configured to receive lubricating oil from a lubricating oil passage formed inside the connecting rod,
the bearing layer is formed with a notch through which the lattice structure is exposed to an inner circumferential side,
The lattice structure includes a first lattice structure having a first porosity and a second lattice structure having a second porosity greater than the first porosity;
The second lattice structure portion is arranged facing the cutout portion and is configured to be exposed on the inner circumferential side. 2. The engine bearing metal according to claim 1, wherein the lattice structure portion is provided toward the big end side in the axial direction of the connecting rod with respect to a center line passing through a cross-sectional center of the through hole. A bearing metal for rotatably connecting a connecting rod to a shaft, which is a crank pin of a crankshaft, disposed in a through hole formed in a big end of the connecting rod,
A main body portion is installed on an inner circumferential surface of the through hole;
a bearing layer formed on an inner circumferential side of the main body, the bearing layer having a sliding surface configured to be slidable relative to the shaft;
Equipped with
the body portion includes a lattice structure formed on at least a portion of the body portion;
The lattice structure is configured to receive lubricating oil from a lubricating oil passage formed inside the engine body,
the bearing layer is formed with a notch through which the lattice structure is exposed to an inner circumferential side,
The lattice structure includes a first lattice structure having a first porosity and a second lattice structure having a second porosity greater than the first porosity;
The second lattice structure portion is arranged facing the cutout portion and is configured to be exposed on the inner circumferential side. The engine bearing metal according to claim 3, wherein the lattice structure is disposed toward the small end of the connecting rod in the axial direction from a center line passing through the cross-sectional center of the through hole. A bearing metal for rotatably supporting a shaft, which is a crank journal of a crankshaft, installed in a through hole formed in an engine body, comprising:
A main body portion is installed on an inner circumferential surface of the through hole;
a bearing layer formed on an inner circumferential side of the main body, the bearing layer having a sliding surface configured to be slidable relative to the shaft;
Equipped with
the body portion includes a lattice structure formed on at least a portion of the body portion;
The lattice structure is configured to receive lubricating oil from a lubricating oil passage formed inside the engine body,
the bearing layer is formed with a notch through which the lattice structure is exposed to an inner circumferential side,
The lattice structure includes a first lattice structure having a first porosity and a second lattice structure having a second porosity greater than the first porosity;
The second lattice structure portion is arranged facing the cutout portion and is configured to be exposed on the inner circumferential side. 6. The engine bearing metal according to claim 5, wherein the lattice structure portion is provided on a lower side of the engine body than a center line passing through a cross-sectional center of the through hole.

Images