JP2022174623A - Half-split bearing, internal combustion engine, and vehicle - Google Patents

Abstract

To provide a bearing having improved friction while suppressing the seizure due to one-side contact.SOLUTION: A half-split bearing (1) includes a semi-cylindrical bearing body (11) including an inner peripheral face (12) which slides with a mating shaft (9), and slopes (121, 122) formed on at least one end of the inner peripheral face (12) in the axial direction of the mating shaft (9) all over the circumference. In the half-split bearing (1), the depths of the slopes (121, 122) are different in the peripheral direction.SELECTED DRAWING: Figure 3

Description

The present invention relates to half bearings, internal combustion engines, and automobiles.

It is known to form a taper at the axial ends of a half bearing. For example, Patent Literature 1 discloses a connecting rod bearing in which crownings having different widths in the circumferential direction are formed in order to prevent uneven contact of the shaft due to elastic deformation while suppressing a decrease in load capacity.

Japanese Patent No. 3955737

Although the load applied to the bearing is not uniform in the circumferential direction, the crowning depth of the bearing described in Patent Document 1 is constant in the circumferential direction. The bearing described in Patent Document 1 has room for improvement in friction.

In contrast, the present invention provides a bearing that suppresses seizure due to uneven contact and improves friction.

The present invention comprises a bearing body having a semi-cylindrical shape including an inner peripheral surface that slides on a shaft, and an inclination formed along the entire circumference of at least one end of the inner peripheral surface in the axial direction of the shaft. and the depth of the inclination varies in the circumferential direction.

The depth of the inclination may be deeper in the vicinity of the mating surfaces than in the center in the axial direction.

The slope may be wider in the vicinity of the mating surface than at the center in the axial direction.

The inner peripheral surface may have the inclination at both ends in the axial direction.

The inclination may be formed at both ends of the inner peripheral surface in the axial direction, and the two inclinations may be connected at a boundary between the inner peripheral surface and the mating surface.

The half bearing may have a plurality of grooves formed on the inner peripheral surface and the inclination and extending over the entire circumference in the circumferential direction.

The present invention also provides an internal combustion engine using the half bearing according to any one of the above.

Furthermore, the present invention provides a motor vehicle having an internal combustion engine as described above.

ADVANTAGE OF THE INVENTION According to this invention, friction can be improved, suppressing seizure by uneven contact.

The figure which illustrates the structure of the bearing 10 which concerns on one Embodiment. The figure which illustrates the structure of the half bearing 1 which concerns on one Embodiment. FIG. 4 is a diagram illustrating shapes of slopes 121 and 122; 4A and 4B are diagrams illustrating the structure of a jig 90; FIG. 4A and 4B are diagrams showing a method of manufacturing the half bearing 1; 4A and 4B are diagrams showing a method of manufacturing the half bearing 1; 4A and 4B are diagrams showing a method of manufacturing the half bearing 1; 4A and 4B are diagrams showing a method of manufacturing the half bearing 1; 4A and 4B are diagrams showing a method of manufacturing the half bearing 1; 4 shows measurement results of surface profiles of Examples and Comparative Examples. The figure which illustrates the simulation result of stress distribution. The figure which illustrates the simulation result of contact pressure. FIG. 12 is a diagram showing another example of the shape of the slope 121 and the slope 122; FIG. 12 is a diagram showing another example of the shape of the slope 121 and the slope 122; FIG. 12 is a diagram showing another example of the shape of the slope 121 and the slope 122; The figure which illustrates the surface shape of the internal peripheral surface 12 which concerns on a modification.

1. Configuration In the bearing according to the present embodiment, crowning is formed on the sliding surface to suppress uneven contact of the shaft. Techniques for forming a crowning on the sliding surface of a bearing are conventionally known, but in the conventional technique, the depth of the crowning is constant in the circumferential direction. Moreover, traditionally, bearings that are expected to be subjected to higher loads due to engine specifications have employed designs with uniformly deeper crownings (than those used in low-load environments). Alternatively, there is a design concept of forming a crowning in a region where a high load is expected and not forming a crowning in a region where a low load is expected, as in the bearing of Patent Document 1.

Here, the friction F in a lubricating oil environment is generally expressed by the following equation.
F=μ・U/h
μ is the viscosity of the lubricating oil, U is the rotation speed of the mating shaft, and h is the distance between the sliding surface of the bearing and the mating shaft. In this way, from the viewpoint of improving friction, it is actually preferable to have a deeper crowning in a region where the load is assumed to be low. The present invention addresses this problem.

From the origin of the word, "crowning" may be understood to refer to those formed on both sides in the axial direction. It may be formed only on one side instead of on one side. Therefore, hereinafter, the surface shape corresponding to the crowning is expressed as "tilt".

FIG. 1 is a diagram illustrating the structure of a bearing 10 according to one embodiment. The bearing 10 is, for example, a bearing used as a main bearing in an internal combustion engine of an automobile. The bearing 10 slides on the mating shaft 9 and supports the mating shaft. A bearing 10 is fixed to the housing 8 . FIG. 1 shows a cross section parallel to the axial direction of the mating shaft 9 and passing through the radial center of the mating shaft 9 . The bearing 10 consists of two half bearings, specifically half bearing 1 and half bearing 2 . In one example, the housing 8 is the cylinder block of an automobile engine (i.e. internal combustion engine) and the mating shaft 9 is the crankshaft (specifically the main journal or crankpin of the crankshaft).

FIG. 2 is a diagram illustrating the structure of the half bearing 1 according to one embodiment. FIG. 2A shows a top view, and FIG. 2B shows a side view. The half bearing 1 has a semi-cylindrical bearing body 11 . A semi-cylindrical shape refers to a shape obtained by dividing a cylinder in half along a plane parallel to the axial direction. The bearing body 11 is made of a material that satisfies the properties required in the environment in which it is used, such as metal, resin, or a composite material thereof. As the metal material, for example, an iron-based alloy (such as steel or cast iron), an aluminum-based alloy, or a copper-based alloy is used. As the resin material, for example, polyamideimide (PAI), polyimide (PI), polyamide (PA), polyetheretherketone (PEEK), or a composite material thereof is used. These resins may be used as binder resins, and additives may be dispersed in the binder resins. Additives include solid lubricants (polytetrafluoroethylene (PTFE), MoS2, graphite, etc.), hard substances (SiC, Al2O3, Si3N4, etc.), and soft substances (Sn, Al, Bi, etc.). Includes 1 species. In one example, the bearing body 11 is made of metal and does not have a resin coating layer. Furthermore, as a composite material, a coating layer of a resin material (for example, the resin coating layer described above) is used on a metal material (for example, a bearing layer of an aluminum-based alloy or a copper-based alloy laminated on a steel base layer). may As another composite material, a soft metal material (e.g. Sn, Sn alloy, Bi, Bi A coating layer of a metal plating layer such as an alloy) may be used.

The bearing body 11 has an inner peripheral surface 12 , an outer peripheral surface 13 , a mating surface 14 and a mating surface 15 . The inner peripheral surface 12 slides on the mating shaft 9 . The inner peripheral surface 12 has slopes 121 and 122 at one end and the other end (that is, both ends) in the axial direction of the mating shaft 9 . The slopes 121 and 122 will be described later. The outer peripheral surface 13 contacts the housing 8 . The outer peripheral surface 13 may have a surface structure (eg, protrusions or pawls) that restrains the half bearing 1 from slipping relative to the housing 8 . The mating surfaces 14 and 15 are in contact with the mating surfaces of the half bearing 2 . A cylindrical bearing 10 is constructed by combining the half bearing 1 and the half bearing 2 . In this example, half bearing 2 has a structure similar to half bearing 1, except that it does not have slopes corresponding to slopes 121 and 122. FIG.

For the following explanation, polar coordinates are defined with the center C of the arc drawn by the outer peripheral surface 13 as the origin. A line connecting the center of the outer peripheral surface 13 in the circumferential direction and the center C is defined as an angle θ=0, and the clockwise direction in the drawing is defined as the positive direction, and the counterclockwise direction is defined as the negative direction. The angle θ is called the bearing angle.

FIG. 3 is a diagram illustrating the shapes of the slopes 121 and 122. FIG. FIGS. 3A, 3B, and 3C respectively show the AA cross section, the BB cross section, and the CC cross section in the top view of FIG. 2A. Note that in these drawings, the magnitudes of the slopes 121 and 122 are exaggerated for ease of explanation. The slopes 121 and 122 are also exaggerated in aspect ratio and shown deeper than they actually are. The slopes 121 and 122 are surface shapes corresponding to crowning as described above, and refer to gently sloped surface shapes. Specifically, the depth of the tilt (the radial length of the bearing, d1 and d2 in the figure) is several orders of magnitude smaller than the width of the tilt (the axial length, w1 and w2 in the figure). In one example, the width of the slope is a few mm and the depth is a few μm, the depth being on the order of 1/1000 of the width. In the related art, bearings with chamfered sliding surfaces are known. "Chamfering" refers to a surface shape having approximately the same width and depth. In one example, the chamfer is on the order of several millimeters in width and depth. In addition, in the AA cross section or the BB cross section, the angle formed by the inclination 121 and the inclination 122 with the reference plane (eg, the outer peripheral surface 13) is preferably less than 0.6°, and less than 0.15°. is more preferably less than 0.06°. In contrast, the chamfer angle is about 30-60°. In these meanings, the term "tilt" in this embodiment refers to a surface shape different from chamfering.

AA cross section in FIG. 3A is a cross section parallel to the axial direction at the center of the bearing body 11 in the circumferential direction. At the center in the circumferential direction, ramps 121 and 122 have width w1 and depth d1. The BB cross section in FIG. 3B is a cross section parallel to the axial direction at the circumferential end of the bearing body 11 (that is, the boundary with the mating surface). At the circumferential ends, ramps 121 and 122 have width w2 and depth d2. Comparing the circumferential ends of the slopes 121 and 122 with the circumferential center, the circumferential ends are wider and deeper. That is, w2>w1 and d2>d1.

The CC cross section in FIG. 3C actually has a semi-cylindrical shape, but here, in order to clarify the depth profile of the slopes 121 and 122, the outer peripheral surface 13 is linearly developed. Shows an exploded view. The slopes 121 and 122 are formed over the entire circumference. That is, one end of each of the slopes 121 and 122 in the circumferential direction reaches (that is, connects to) the mating surface 14 , and the other end reaches (that is, connects to) the mating surface 15 . The depths of the slopes 121 and 122 are different in the circumferential direction. In the range of θ1<θ<θ2, the depths of the slopes 121 and 122 are substantially constant. The values of θ1 and θ2 are designed according to the environment in which the bearing 10 is used (for example, engine type). In one example, assuming a V-type engine, it is preferable that θ1<−60° and θ2>60°.

In the range of θ<θ1, the depths of the slopes 121 and 122 gradually increase toward the mating surface 14 . Similarly, the depths of the slopes 121 and 122 gradually increase toward the mating surface 14 in the range of θ>θ2. The relationship between depth d2 and depth d1 is
d2=kd1
can be expressed as The coefficient k is preferably greater than 1.2, more preferably greater than 1.5, and even more preferably greater than 2.0.

Although the description is omitted here, the half bearing 1 may have a crush relief. The crush relief is a relief formed in the vicinity of the mating surface along the circumferential direction on the inner peripheral surface 12 . The depth of the crush relief is greater than the depth of the slopes 121 and 122 . θ1 and θ2 may be inside or outside the crush relief.

Although FIG. 3 shows the depth profiles of slopes 121 and 122, the same applies to widths. That is, the widths of the slopes 121 and 122 are substantially constant in the range of θ1<θ<θ2 (θ1 and θ2 are common to the depth profile). In the range of θ<θ1, the depths of the slopes 121 and 122 gradually widen toward the mating surface 14 . In the range of θ>θ2, the depths of the slopes 121 and 122 gradually widen toward the mating surface 14 .

2. Manufacturing Method A method of manufacturing the half bearing 1, particularly a method of forming the slopes 121 and 122 will be described. First, an operator prepares the jig 90 . A jig 90 is a device that supports the half bearing during the following steps.

FIG. 4 is a diagram illustrating the structure of the jig 90. As shown in FIG. 4A shows a top view, FIG. 4B shows a front view, and FIG. 4C shows a DD cross section. When describing the mutual positional relationship of the constituent elements of the jig 90, the coordinate system used when describing the half bearing 1 will be used. The jig 90 has a semi-cylindrical inner peripheral surface 91 . Jig 90 supports the half bearing on inner peripheral surface 91 . The inner peripheral surface 91 has projections 92 and projections 93 . The protrusions 92 and 93 are formed on both axial ends of the inner peripheral surface 91 . The protrusions 92 and 93 are formed along the entire circumference of the inner peripheral surface 91 . The shapes of the protrusions 92 and 93 are designed according to the desired slope shape. In one example, the protrusions 92 and 93 are protrusions having a height of several μm and a width of several μm. The protrusions 92 and 93 are formed by cutting, welding, plating, or the like.

A method of forming the slopes 121 and 122 will now be described with reference to FIGS. The operator attaches the half bearing (with slopes 121 and 122 not yet formed) to jig 90 (FIG. 5). The half bearing is attached so that the outer peripheral surface 13 is in contact with the protrusions 92 and 93 . With the half bearing attached to the jig 90, the operator applies pressure to the half bearing (FIG. 6). In one example, the operator applies pressure to mating surfaces 14 and 15 .

When no pressure is applied, the outer peripheral surface 13 of the half bearing is parallel to the inner peripheral surface 91 of the jig 90 (FIG. 7, and FIGS. 7 to 9 correspond to the DD section). When pressure is applied to the half bearing, the half bearing elastically deforms (that is, bends) according to the heights of the protrusions 92 and 93 so that the vicinity of the center in the axial direction protrudes toward the outer periphery (Fig. 8). . The operator cuts the inner peripheral surface 12 of the half bearing while applying pressure. Cutting is performed with a blade that rotates about the center C of the bearing. The cutting surface by this blade is parallel to the axial direction (dashed line in FIG. 8). This process cuts the axial ends of the half bearing more than the center (Fig. 9). Since pressure is applied from the mating surfaces 14 and 15, the amount of elastic deformation is greater near the mating surfaces 14 and 15, and is smaller at the center in the circumferential direction. Therefore, by cutting with the rotary blade, a wider and deeper slope is formed in the vicinity of the mating surfaces 14 and 15 .

3. EXAMPLES The inventors of the present application conducted a half bearing 1 (Example), a half bearing without crowning (Comparative Example 1), and a half bearing in which a uniform crowning was formed in the circumferential direction (Comparative Example 2). ) was fabricated and its surface profile was measured.

FIG. 10 shows the measurement results of the surface profiles of Example and Comparative Examples 1 and 2. FIG. In the embodiment, a slope of about 3 to 4 mm wide and about 2 to 3 μm deep is formed in the center and about 4.5 to 9 mm wide and about 3 to 4 μm deep in the vicinity of the mating surface. No inclination is observed in Comparative Example 1 (for the convenience of the experiment, the surface of Example 1 has large irregularities because the surface cutting conditions are different from those of the others). In Comparative Example 2, a slope with a width of about 3.5 mm and a depth of about 5 μm is formed regardless of the position in the circumferential direction. In this way, when the surface profile is measured, half bearings in which inclinations having different widths and depths depending on the position in the circumferential direction, such as half bearing 1, are formed. It can be seen that this is different from half bearings in which no or a uniform inclination is formed.

FIG. 11 is a diagram illustrating simulation results of stress distribution in a lower half bearing of a main bearing in a V6 engine. The simulation of FIG. 11 was performed under the following conditions using not the half bearing 1 according to the present embodiment but the half bearing according to the related art (half bearing without crowning at the ends in the axial direction).
Analysis conditions: EHL (elastohydrodynamic lubrication) analysis Model: V6 supercharged engine Rotational speed: 6,000 rpm
As the simulation results show, in the V6 engine lower half bearing, a large load is applied near the center in the circumferential direction (although there are differences depending on the position of the bearing), and the load near the mating surface is relatively small. I understand. Therefore, if the half bearing 1 according to the embodiment is used, the load is applied with a narrow slope (that is, a wide sliding surface) in the area where the load is large, and the area where the load is small has a deeper inclination, thereby improving the friction. be able to.

FIG. 12 is a diagram illustrating simulation results of contact pressure on the #3 journal in a V6 engine. In addition, in the half bearing 1 according to the present embodiment, the load applied to each cross section (for example, the AA cross section, the BB cross section, and the CC cross section in FIG. 3) is different, so the comparison should be made under the same conditions. difficult to do. Therefore, here, the dependency of the contact pressure on the crowning width is shown when it is assumed that the crowning of the same width is formed on the entire circumference. From FIG. 12, it can be seen that contact pressure decreases (that is, friction improves) as the crowning width increases. According to the simulation results of FIG. 12, in Comparative Example 1 (crowning width: equivalent to zero mm), the contact pressure is about twice as high as in the case where the crowning is provided. In Comparative Example 2, since the crowning is formed uniformly in the circumferential direction, there is room for improvement in the friction in areas where the load is small, such as the vicinity of the mating surfaces.

4. Modifications The present invention is not limited to the above-described embodiments, and various modifications are possible. Some modifications will be described below. Two or more of the items described in the following modified examples may be applied in combination.

13A and 13B are diagrams showing examples of other shapes of the slopes 121 and 122. FIG. 13 to 15 show top views of the half bearing 1. FIG. In this example, the slopes 121 and 122 are connected at the boundary between the mating surface 14 and the inner peripheral surface 12 (that is, the inner peripheral surface 12 has no flat portion). As already explained, since the load is small in the vicinity of the mating surfaces, there is no problem even if the inner peripheral surface 12 is inclined over the entire axial direction. As a result, the slopes 121 and 122 in the vicinity of the mating surfaces can be made deeper, and friction can be further improved.

FIG. 14 is a diagram showing still another shape example of the slopes 121 and 122. In FIG. In this example, the depths of the slopes 121 and 122 gradually increase from the center in the circumferential direction toward the mating surfaces (the illustrated profile is the width profile of the slopes 121 and 122, but the depth profile). For example, in an environment (for example, an L-type engine) in which the load is expected to be more concentrated at the center in the circumferential direction, adopting such a structure can further improve friction.

FIG. 15 is a diagram showing still another shape example of the slopes 121 and 122. FIG. In this example, only the slope 121 is formed on the inner peripheral surface 12 and the slope 122 is not formed. That is, the inclination is formed only on one side in the axial direction. For example, such a structure is effective in an environment where it is assumed that the mating shaft will have uneven contact on only one side in the axial direction.

FIG. 16 is a diagram illustrating the surface shape of the inner peripheral surface 12 according to the modification. In this example, the inner peripheral surface 12 is formed with a plurality of grooves 123 . The groove 123 is a groove extending along the entire circumference of the inner peripheral surface 12 along the circumferential direction. These plurality of grooves 123 are formed with an interval p between adjacent grooves. Each groove 123 is of width wg and height h. Although the figures exaggerate the height h, the height h is on the order of 1/100, 1/1000 or even less of the spacing p. Width wg is the distance between the tops of individual grooves 123 . Assuming that the maximum depth of the slopes 121 and 122 is dmax, h≧dmax. In this example wg=p in the unused state. When the half bearing 1 of this example is used, the apex of the groove 123 wears with use and the width wg and height h decrease. In use, wear begins first with the grooves 123 on the slopes 121 and 122 . Although the amount of wear varies depending on the environment, when it wears to a certain extent, the portions other than the slopes 121 and 122 (referred to as land portions) serve as plateau surfaces, the load capacity increases, and the wear stops. In a low or moderate load environment, the line connecting the tops of the grooves 123 wears flat (in the cross-section of FIG. 16) (i.e. the slopes 121 and 122 have a higher height h than the lands). high). In a high load environment, the tops of grooves 123 on ramps 121 and/or ramps 122 wear more, and grooves 123 on ramps 121 and 122 wear as much or more than grooves 123 on lands. Since the half bearing 1 of this example utilizes the wear of the grooves 123, it is possible to obtain the effect of improving the friction even with an engine of any load.

The shapes of the slopes 121 and 122 described in the embodiment are merely examples, and the present invention is not limited to these. For example, the slopes 121 and 122 may be deepest at the circumferential center and shallower as they approach the mating surfaces. Also, the slopes 121 and 122 may not be symmetrical upstream and downstream in the rotational direction with respect to the center in the circumferential direction. The slopes 121 and 122 may deepen only upstream or only downstream in the direction of rotation. Furthermore, the widths of the slopes 121 and 122 are not limited to increasing or decreasing according to the depth. Ramp 121 and ramp 122 may have a constant width and vary in depth in the circumferential direction. The slopes 121 and 122 can be adjusted in shape and position by adjusting the shape and/or position of the protrusions 92 and 93 of the jig 90, for example. The method of forming the slopes 121 and 122 described in the embodiment is merely an example, and the slopes 121 and 122 may be formed by press working, for example.

DESCRIPTION OF SYMBOLS 1... Half bearing, 2... Half bearing, 8... Housing, 9... Mating shaft, 10... Bearing, 11... Bearing main body, 12... Inner peripheral surface, 13... Outer peripheral surface, 14... Mating surface, 15... Mating surface , 90... jig, 91... inner peripheral surface, 92... protrusion, 93... protrusion, 121... inclination, 122... inclination, 123... groove

Claims (8)

a bearing body having a semi-cylindrical shape including an inner peripheral surface that slides on the shaft;
a slope formed along the entire circumference of at least one end of the inner peripheral surface in the axial direction of the shaft;
A half bearing in which the depth of the inclination differs in the circumferential direction. 2. The half bearing according to claim 1, wherein the depth of said inclination is deeper in the vicinity of the mating surfaces than in the center in the axial direction. 3. The half bearing according to claim 1, wherein the inclination is wider in the vicinity of the mating surfaces than in the center in the axial direction. The half bearing according to any one of claims 1 to 3, wherein the inner peripheral surface has the inclination at both ends in the axial direction. The halves according to any one of claims 1 to 4, wherein the slopes are formed at both ends of the inner peripheral surface in the axial direction, and the two slopes are connected at the boundary between the inner peripheral surface and the mating surface. bearing. 6. The half bearing according to any one of claims 1 to 5, further comprising a plurality of grooves formed in said inner peripheral surface and said inclination and extending all around in said circumferential direction. An internal combustion engine using the half bearing according to any one of claims 1 to 6. A motor vehicle having an internal combustion engine according to claim 7.

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