WO2025166808A1

WO2025166808A1 - Crankshaft thrust bearing

Info

Publication number: WO2025166808A1
Application number: PCT/CN2024/077100
Authority: WO
Inventors: Yun Gao; Qing Zhang; Chang Liu
Original assignee: Cummins Inc
Current assignee: Cummins Inc
Priority date: 2024-02-09
Filing date: 2024-02-09
Publication date: 2025-08-14
Anticipated expiration: 2026-08-09

Abstract

A semi-annularly shaped half thrust bearing configured to receive an axial force of a crankshaft of an internal combustion engine. The half thrust bearing includes a slide surface configured to receive the axial force and a back surface on an opposite side thereof. The slide surface includes a plurality of pad surfaces, wherein the plurality of pad surfaces include first and fourth pad surfaces each having a first ramp profile and second and third pad surfaces each having a second ramp profile. The slide surface includes first and second thrust reliefs that respectively span from first and second end surfaces to first and fourth pad surfaces. The first and second ramp profiles are asymmetric and the first and second thrust reliefs are sized to receive portions of the engine block that may swell. An oil groove is positioned between two of the pad surfaces.

Description

CRANKSHAFT THRUST BEARING

TECHINICAL FIELD

The present application relates generally to thrust bearing for a crankshaft, and more particularly to the thrust bearing having one or more ramp profiles and a thrust relief.

BACKGROUND

A crankshaft of an internal combustion engine is rotatably supported, at a journal portion thereof, by a cylinder block lower portion of the internal combustion engine by a main bearing. The main bearing can be configured by combining a pair of half bearings into a cylindrical shape. One or both of the pair of half bearings are used in combination with a half thrust bearing which receives axial force or thrust load of the crankshaft.

Internal combustion engines often require high thrust capacity for the half thrust bearing. Therefore, the half thrust bearing is required to accommodate the high thrust capacity. Moreover, portions of the engine block may swell due to axial force or thrust load of the crankshaft which can cause deformation of the half thrust bearing and material peel off of the deformed portion of the half thrust bearing. Therefore, further improvements in this area of technology are needed.

SUMMARY

The present disclosure includes a semi-annularly shaped half thrust bearing configured to receive an axial force of a crankshaft of an internal combustion engine. The half thrust bearing includes a slide surface configured to receive the axial force and a back surface on an opposite side thereof. The slide surface includes a plurality of pad surfaces and a first thrust relief and a second thrust relief. The plurality of pad surfaces include first and fourth pad surfaces each having a first ramp profile, and second and third pad surfaces each having a second ramp profile. The first thrust relief spans from a first end surface to the first pad surface and the second thrust relief spans from a second end surface to the fourth pad surface.

In an embodiment, the first ramp profile is an asymmetric profile as measured along a radial centerline of the slide surface. In a further refinement, the second ramp profile is a second asymmetric profile as measured along a radial centerline of the slide surface, wherein the second ramp profile is different than the first ramp profile.

In an embodiment, the first ramp profile on each of the first and fourth pad surfaces extends between a first peak that corresponds to a maximum height to a first valley that corresponds to a lowest height of the first ramp profile.

In an embodiment, the second ramp profile on each of the second and third pad surfaces extends between a second peak that corresponds to a maximum height to a second valley that corresponds to a lowest height of the second ramp profile. In a further refinement, the second ramp profile is higher than the first ramp profile as measured relative to either a first thrust relief surface of the first thrust relief or a second thrust relief surface of the second thrust relief.

In an embodiment, the first valley of the first pad surface is located adjacent the first thrust relief, and wherein the first peak of the fourth pad surface is located adjacent the second thrust relief. In a further refinement, the second valley of the second pad surface is located closer to the first pad surface than the third pad surface, and wherein the second peak of the third pad surface is located closer to the fourth pad surface than the second pad surface.

In an embodiment, the first and second peaks of each of the first, second, third, and fourth pad surfaces are circumferentially arranged in a similar orientation.

In an embodiment, the first thrust relief has a first thrust relief surface and the first peak of the first ramp profile has a profile height of about 0.07 mm as measured relative to the first thrust relief surface. In a further refinement, the first thrust relief has a first thrust relief surface and the first peak of the second ramp profile has a profile height of about 0.09 mm as measured relative to the first thrust relief surface.

In an embodiment, the first and the second thrust relief surfaces are flat.

In an embodiment, the slide surface includes a plurality of oil grooves arranged such that a first one of the oil grooves is positioned between the first and second pad surfaces, a second one of the oil grooves is positioned between the second and third pad surfaces, and a third one of the oil grooves is positioned between the third and fourth pad surfaces.

In an embodiment, the first and fourth pad surfaces each have a circumferential length extending over a circumferential angle of 20° or more and 25° or less, at any radial positions of the half thrust bearing. In a further refinement, the second and third pad surfaces each have a circumferential length extending over a circumferential angle of 35° or more and 45° or less, at any radial positions of the half thrust bearing.

In an embodiment, the back surface is flat.

This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The concepts described herein are illustrative by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. Where considered appropriate, references labels have been repeated among the figures to indicate corresponding or analogous elements.

FIG. 1 is a front view of a half thrust bearing.

FIG. 2 is a schematic graph of a first ramp profile and a second ramp profile of the half thrust bearing of FIG. 1.

FIG. 3 is another front view of the half thrust bearing of FIG. 1.

FIG. 4 is a first partial end view of the half thrust bearing of FIG. 1.

FIG. 5 is a second partial end view of the half thrust bearing of FIG. 1.

FIG. 6 is a perspective view of a bearing assembly including the half thrust bearing of FIG. 1 positioned as a front thrust bearing and a rear thrust bearing in an illustrative embodiment of an engine block.

FIG. 7 is a partial view of a front thrust pocket of the engine block of FIG. 6.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated herein.

Turning now to the present application with reference to FIGS. 1-5, a first configuration of a half thrust bearing 10 will be described. The half thrust bearing 10 can be employed as an upper half (front) or lower half (rear) thrust bearing in a crankshaft assembly within an engine block. The half thrust bearing 10 includes a half thrust bearing body 12 that is semicircular in shape and extends between a first end surface 14 and an opposite second end surface 16. The half thrust bearing body 12 includes an inner-diameter-side end surface 12i and an outer-diameter-side end surface 12o and a width, w, that spans between the inner-diameter-side end surface 12i and the outer-diameter-side end surface 12o.

The half thrust bearing body 12 includes a slide or bearing surface 18 opposite a back surface 19 wherein the slide surface 18 and the back surface 19 extend in a circumferential range between the first and second end surfaces 14 and 16, respectively. The slide surface 18 receives an axial force f from the crankshaft. The slide surface 18 includes a first pad surface 20, a second pad surface 22, a third pad surface 24, and a fourth pad surface 26 that are described in further detail below. The back surface 19 is substantially flat or flat.

The first and second pad surfaces 20 and 22, respectively, are separated by an oil groove 30a. The second and third pad surfaces 22 and 24, respectively, are separated by an oil groove 30b. The third and fourth pad surfaces 24 and 26, respectively, are separated by an oil groove 30c. The oil grooves 30a-c are similar to one another however in other embodiments the oil grooves 30a-c may be sized differently from each other. The oil grooves 30a-c are configured to retain oil therein. In one embodiment illustrated in FIG. 3, a centerline of the oil groove 30c is about 45° from the second end surface 16, a centerline of the oil groove 30b is about 90° from the second end surface 16, and a centerline of the oil groove 303 is about 135° from the second end surface 16. In other embodiments, the oil grooves 30a-c are arranged differently on the slide surface 18. For example, the oil grooves 30a-c can be arranged such that oil grooves 30a and 30c are further apart than 45° from the centerline of the oil groove 30b.

Although the four pad surfaces 20, 22, 24, and 26 are arranged and separated by the oil grooves 30a-c in the circumferential direction on the slide surface 18 of the half thrust bearing body 12 in the present embodiment, the number of the pad surfaces 20, 22, 24, and 26 may be more than or less than four, and three to six pad surfaces are generally formed. Although three oil grooves 30a-c are arranged apart in the circumferential direction on the slide surface 18 of the half thrust bearing body 12 in the present embodiment, the number of the oil grooves 30a-c may be more than or less than three, and two to five oil grooves are generally formed.

The slide surface 18 also includes a first thrust relief 32 that spans from the first end surface 14 to the first pad surface 20. The slide surface 18 also includes a second thrust relief 34 that spans from the second end surface 16 to the fourth pad surface 26.

The first thrust relief 32 has a first thrust relief length L1 and a second thrust relief length L2 that are each measured in a perpendicular direction from the first end surface 14 and extend to the first pad surface 20. In the illustrated embodiment, the first thrust relief length L1 is the same or substantially the same as the second thrust relief length L2. In other embodiments, the first thrust relief length L1 is longer or shorter than the second thrust relief length L2. The first and second thrust relief lengths L1 and L2 are sized to reduce contact pressure between an engine block surface that may swell and a peak height of the slide or bearing surface 18. Beneficially, the first thrust relief 32 is sized to accommodate potential swelling of the engine block surface. In one embodiment, the first and second thrust relief lengths L1 and L2 from the first end surface 14 of the half thrust bearing 10 are about 20 mm. The first thrust relief 32 has an axial thickness T1 that is measured from the bottom surface 19 to a first thrust relief surface or plane 40 of the first thrust relief 32. The first thrust relief surface or plane 40 is flat or substantially flat. In the illustrated embodiment, the first thrust relief 32 includes an overhang portion 33 wherein the overhang portion 33 includes a length 35 and a width 37. In other embodiments, the first thrust relief 32 does not include the overhang portion 33.

The second thrust relief 34 has a first thrust relief length L3 and a second thrust relief length L4 that are each measured in a perpendicular direction from the second end surface 16 and extend to the fourth pad surface 26. In the illustrated embodiment, the first thrust relief length L3 is the same or substantially the same as the second thrust relief length L4. In other embodiments, the first thrust relief length L3 is longer or shorter than the second thrust relief length L4. The first and second thrust relief lengths L3 and L4 are sized to reduce contact pressure between an engine block surface that may swell and a peak height of the slide or bearing surface 18. As such the second thrust relief 34 is sized to accommodate potential swelling of the engine block surface. In one embodiment, the first and second thrust relief lengths L3 and L4 from the second end surface 16 of the half thrust bearing 10 are about 20 mm. The second thrust relief 34 has an axial thickness T2 that is measured from the bottom surface 19 to a second thrust relief surface or plane 42 of the second thrust relief 34. The second thrust relief surface or plane 42 is flat or substantially flat.

The first pad surface 20 has a first ramp profile 54 wherein the first ramp profile 54 extends between a first peak 50 that is a maximum height to a first valley 52 that is a minimum or lowest height of the first pad surface 20. The first valley 52 is located adjacent the first thrust relief 32. At one location on the first pad surface 20, the first ramp profile 54 is constant as measured radially from the inner-diameter-side end surface 12i to the outer-diameter-side end surface 12o. In the illustrated embodiment, the first ramp profile 54 varies in an asymmetric profile along a radial centerline CL of the slide surface 18 as measured in an angle 56 from the first peak 50 to the first valley 52. The asymmetric profile of the first ramp profile 54 conforms to engine block deformation or swelling that can occur over time and use of the engine and crankshaft. In one embodiment illustrated in FIG. 2, the first peak 50 has a profile height of about 0.07 mm as measured relative to the first thrust relief surface or plane 40. Further in this embodiment, the first valley 52 is level with the first thrust relief surface or plane 40 or has a profile height of about 0.0 mm as measured relative to the first thrust relief surface or plane 40. In the illustrated embodiment in FIG. 2, the profile height of the first ramp profile 54 is determined by the following formula:

Profile height= (Angle*67.5) ∧2/ (2*5735) , wherein Angle is angle 56 measured in radians.

The fourth pad surface 26 is similar to the first pad surface 20 and includes the first ramp profile 54 however the first ramp profile 54 on the fourth pad surface 26 is arranged such that the first peak 50 is closest to the second thrust relief 34. An illustrative embodiment of the first ramp profile 54 is shown in FIG. 2. In other embodiments, other configurations of the first ramp profile 54 are contemplated.

The second pad surface 22 has a second ramp profile 64 wherein the second ramp profile 64 extends between a second peak 60 that is a maximum height to a second valley 62 that is a minimum or lowest height of the second pad surface 22. The second peak 60 is located adjacent to oil groove 30b and the second valley 62 is located adjacent the oil groove 30a. At one location on the second pad surface 22, the second ramp profile 64 is constant as measured radially from the inner-diameter-side end surface 12i to the outer-diameter-side end surface 12o. In the illustrated embodiment, the second ramp profile 64 varies in an asymmetric profile along a radial centerline CL of the slide surface 18 as measured in the angle 56 from the second peak 60 to the second valley 62. In one embodiment illustrated in FIG. 2, the second peak 60 has a profile height of about 0.09 mm as measured relative to the first thrust relief surface or plane 40. Further in this embodiment, the second valley 62 is level with the first thrust relief surface or plane 40 or has a profile height of about 0.0 mm as measured relative to the first thrust relief surface or plane 40. In the illustrated embodiment, the profile height of the second ramp profile 64 is determined by the following formula:

Profile height= (Angle*67.5) ∧2/ (2*12337) , wherein Angle is angle 56 measured in radians.

The third pad surface 24 is similar to the second pad surface 22 and includes the second ramp profile 64 however the second ramp profile 64 on the third pad surface 24 is arranged such that the second peak 60 is closest to the oil groove 30c and the second valley 62 is closest to the oil groove 30b. An illustrative embodiment of the second ramp profile 64 is shown in FIG. 2. In other embodiments, other configurations of the second ramp profile 64 are contemplated.

In the illustrated embodiment in FIG. 2, the second ramp profile 64 is higher than the first ramp profile 54 as measured relative to either the first thrust relief surface 40 of the first thrust relief 32 or the second thrust relief surface 42 of the second thrust relief 34.

In one embodiment, the first and second peaks 50 and 60 of each of the first, second, third, and fourth pad surfaces 20, 22, 24, and 26 are circumferentially arranged in a similar orientation on the slide surface 18. Further, in this embodiment first and second valleys 52 and 62 of each of the first, second, third, and fourth pad surfaces 20, 22, 24, and 26 are circumferentially arranged in a similar orientation on the slide surface 18.

Beneficially, the first ramp profile 54 on the first and fourth pad surfaces 20 and 26, respectively, and the second ramp profile 64 on the second and third pad surfaces 22 and 24, respectively, are configured to accommodate potential engine block deformation and swelling to reduce contact pressure on the pad surfaces 20, 22, 24, and 26 and thereby avoid material fatigue peel off. Also beneficial is the first thrust relief 32 and the second thrust relief 34 that are sized and configured to accommodate a maximum amount of engine block deformation and swelling to reduce contact pressure on the first and second thrust reliefs 32 and 34, respectively.

Referring to FIGS. 6 and 7, is an illustrative embodiment of an engine block 100 that includes a front thrust pocket 102 that has a depth 104, a width 106, and a circumference sized to receive the half thrust bearing 10. The engine block 100 also includes a rear thrust pocket 102’ (not illustrated) that is similarly sized as the front thrust pocket 102 and receives the half thrust bearing 10. Each of the half thrust bearings 10 are arranged or oriented such that the pad surfaces 20, 22, 24, and 26, and the first and second thrust reliefs 32 and 34 are facing shaft portions of a crankshaft (not illustrated) .

As is evident from the figures and text presented above, a variety of aspects of the present disclosure are contemplated.

Various aspects of the present application are contemplated. According to one aspect, a semi-annularly shaped half thrust bearing configured to receive an axial force of a crankshaft of an internal combustion engine is provided. The half thrust bearing comprises a slide surface configured to receive the axial force and a back surface on an opposite side thereof, wherein the slide surface includes a plurality of pad surfaces, wherein the plurality of pad surfaces include first and fourth pad surfaces each having a first ramp profile, further wherein the plurality of pad surfaces include second and third pad surfaces each having a second ramp profile; and a first thrust relief and a second thrust relief, wherein the first thrust relief spans from a first end surface to the first pad surface, wherein the second thrust relief spans from a second end surface to the fourth pad surface.

In an embodiment, the first ramp profile is an asymmetric profile as measured along a radial centerline of the slide surface.

In an embodiment, the second ramp profile is a second asymmetric profile as measured along a radial centerline of the slide surface, wherein the second ramp profile is different than the first ramp profile.

In an embodiment, the second ramp profile on each of the second and third pad surfaces extends between a second peak that corresponds to a maximum height to a second valley that corresponds to a lowest height of the second ramp profile.

In an embodiment, the second ramp profile is higher than the first ramp profile as measured relative to either a first thrust relief surface of the first thrust relief or a second thrust relief surface of the second thrust relief.

In an embodiment, the first valley of the first pad surface is located adjacent the first thrust relief, and wherein the first peak of the fourth pad surface is located adjacent the second thrust relief.

In an embodiment, the second valley of the second pad surface is located closer to the first pad surface than the third pad surface, and wherein the second peak of the third pad surface is located closer to the fourth pad surface than the second pad surface.

In an embodiment, the first thrust relief has a first thrust relief surface and the first peak of the first ramp profile has a profile height of about 0.07 mm as measured relative to the first thrust relief surface.

In an embodiment, the first thrust relief has a first thrust relief surface and the first peak of the second ramp profile has a profile height of about 0.09 mm as measured relative to the first thrust relief surface.

In an embodiment, the first and the second thrust relief surfaces are flat.

In an embodiment, the first and fourth pad surfaces each have a circumferential length extending over a circumferential angle of 20° or more and 25° or less, at any radial positions of the half thrust bearing.

In an embodiment, the second and third pad surfaces each have a circumferential length extending over a circumferential angle of 35° or more and 45° or less, at any radial positions of the half thrust bearing.

In an embodiment, the back surface is flat.

According to another aspect of the present disclosure, an internal combustion engine comprises the half thrust bearing according to any one or combination of embodiments disclosed herein.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. In reading the claims, it is intended that when words such as “a, ” “an, ” “at least one, ” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Reference throughout this specification to “one embodiment, ” “an embodiment, ” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Appearances of the phrases “in one embodiment, ” “in an embodiment, ” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

Claims

A semi-annularly shaped half thrust bearing configured to receive an axial force of a crankshaft of an internal combustion engine, the half thrust bearing comprising:

a slide surface configured to receive the axial force and a back surface on an opposite side thereof, wherein the slide surface includes:

a plurality of pad surfaces, wherein the plurality of pad surfaces include first and fourth pad surfaces each having a first ramp profile, further wherein the plurality of pad surfaces include second and third pad surfaces each having a second ramp profile; and

a first thrust relief and a second thrust relief, wherein the first thrust relief spans from a first end surface to the first pad surface, wherein the second thrust relief spans from a second end surface to the fourth pad surface.
The half thrust bearing of claim 1, wherein the first ramp profile is an asymmetric profile as measured along a radial centerline of the slide surface.
The half thrust bearing of claim 2, wherein the second ramp profile is a second asymmetric profile as measured along a radial centerline of the slide surface, wherein the second ramp profile is different than the first ramp profile.
The half thrust bearing of any of claims 1-3, wherein the first ramp profile on each of the first and fourth pad surfaces extends between a first peak that corresponds to a maximum height to a first valley that corresponds to a lowest height of the first ramp profile.
The half thrust bearing of any of claims 1-4, wherein the second ramp profile on each of the second and third pad surfaces extends between a second peak that corresponds to a maximum height to a second valley that corresponds to a lowest height of the second ramp profile.
The half thrust bearing of any of claims 2-5, wherein the second ramp profile is higher than the first ramp profile as measured relative to either a first thrust relief surface of the first thrust relief or a second thrust relief surface of the second thrust relief.
The half thrust bearing of any of claims 4-6, wherein the first valley of the first pad surface is located adjacent the first thrust relief, and

wherein the first peak of the fourth pad surface is located adjacent the second thrust relief.
The half thrust bearing of any of claims 5-7, wherein the second valley of the second pad surface is located closer to the first pad surface than the third pad surface, and

wherein the second peak of the third pad surface is located closer to the fourth pad surface than the second pad surface.
The half thrust bearing of any of claims 5-8, wherein the first and second peaks of each of the first, second, third, and fourth pad surfaces are circumferentially arranged in a similar orientation.
The half thrust bearing of any of claims 4-9, wherein the first thrust relief has a first thrust relief surface and the first peak of the first ramp profile has a profile height of about 0.07 mm as measured relative to the first thrust relief surface.
The half thrust bearing of any of claims 4-10, wherein the first thrust relief has a first thrust relief surface and the first peak of the second ramp profile has a profile height of about 0.09 mm as measured relative to the first thrust relief surface.
The half thrust bearing of any of claims 6-11, wherein the first and the second thrust relief surfaces are flat.
The half thrust bearing of any of claims 1-12, wherein the slide surface includes a plurality of oil grooves arranged such that a first one of the oil grooves is positioned between the first and second pad surfaces, a second one of the oil grooves is positioned between the second and third pad surfaces, and a third one of the oil grooves is positioned between the third and fourth pad surfaces.
The half thrust bearing of any of claims 1-13, wherein the first and fourth pad surfaces each have a circumferential length extending over a circumferential angle of 20° or more and 25° or less, at any radial positions of the half thrust bearing.
The half thrust bearing of any of claims 1-14, wherein the second and third pad surfaces each have a circumferential length extending over a circumferential angle of 35° or more and 45° or less, at any radial positions of the half thrust bearing.
The half thrust bearing of any of claims 1-15, wherein the back surface is flat.
An internal combustion engine comprising the half thrust bearing of any of claims 1-16.