FRICTION MINIMIZED SLIDING BEARING ARRANGEMENT

Abstract

The present invention relates to a sliding bearing arrangement for supporting a shaft in a support element, comprising an inner bearing part with a sliding surface and comprising an outer bearing part with a sliding surface, whereas when the shaft is rotating around an axis, the sliding surface of the inner bearing part performs a sliding movement relative to the sliding surface of the outer bearing part. According to the invention, at least one of the sliding surfaces features at least one recess area which is extending in a circumferential direction of the surface over a circumferential angle (1, 2) and which is extending over at least 50% of the axial length of the sliding surface, and the recess area is dimensioned in such a way that over the recess area the clearance distance between the inner bearing part and the outer bearing part is increased.

Claims

1-13. (canceled)

14. A sliding bearing arrangement for supporting a shaft in a support element, the sliding bearing arrangement comprising: an inner bearing part with a sliding surface and an outer bearing part with a sliding surface, whereas when the shaft is rotating around an axis, the sliding surface of the inner bearing part performs a sliding movement relative to the sliding surface of the outer bearing part; and wherein at least one of the sliding surfaces features at least one recess area extending in a circumferential direction of the surface over a circumferential angle (, 2) and which is extending over at least 50% of the axial length of the sliding surface, and the recess area is dimensioned in such a way that over the recess area the clearance distance between the inner bearing part and the outer bearing part is increased.

15. The sliding bearing arrangement according to claim 14 wherein at least one of the sliding surfaces of the inner bearing part and of the outer bearing part features a defined axial length along the rotation axis, whereas the at least one recess area is formed substantially over the entire axial length of the sliding surfaces.

16. The sliding bearing arrangement according to claim 15 wherein at least one of the sliding surfaces are arranged two recess areas, in particular opposing each other.

17. The sliding bearing arrangement according to claim 15 wherein at least one recess area features a depth of at least 0.005 mm and preferably of at least 0.1 mm relating to the original sliding surface.

18. The sliding bearing arrangement according to claim 15 wherein the circumferential directed transition of the recess areas into the surface features a spline.

19. The sliding bearing arrangement according to claim 15 wherein at least one recess area is formed by an area of a continuous varying radius (R) of one of the inner bearing part and the outer bearing part, whereas the recess area formed by the area of a continuous varying radius (R) leads to an elliptic shape of one of the inner bearing part and the outer bearing part.

20. The sliding bearing arrangement according to claim 15 wherein at least one of the surfaces features a pressure load area performed for transferring a force (F) between the shaft and the support element, whereas at least one recess area is located lateral to the pressure load area and the pressure load area is located in between two recess areas.

21. The sliding bearing arrangement according to claim 15 wherein the angle (1, 2) of the circumferential extension of at least one of the recess areas range from 20 to 180.

22. The sliding bearing arrangement according to claim 21 wherein the circumferential extension of at least one of the recess areas ranges from 40 to 160 and most preferred from 50 to 95.

23. The sliding bearing arrangement according to claim 22 wherein the circumferential extension of at least one of the recess areas ranges from 50 to 95.

24. The sliding bearing arrangement according to claim 14 wherein the shaft forms a crank shaft of a crank drive, in particular in one of an internal combustion engine, a compressor and a pump, whereas the inner bearing part is formed by a journal of the crank shaft.

25. The sliding bearing arrangement according to claim 14 wherein the housing forms a connecting rod of a crank drive, in particular in one of an internal combustion engine, a compressor and a pump, whereas the outer bearing part is formed by a big end or small end of connecting rod.

26. The sliding bearing arrangement according to claim 24 wherein the journal of the crank shaft forms a main journal for supporting the crank shaft in a crank housing and the journal of the crank shaft forms a pin journal for connecting the crank shaft to a connecting rod.

27. The sliding bearing arrangement according to claim 25 wherein the journal of the crank shaft forms a main journal for supporting the crank shaft in a crank housing and the journal of the crank shaft forms a pin journal for connecting the crank shaft to a connecting rod.

28. The sliding bearing arrangement according to claim 21 wherein the shaft forms a cam shaft of one of an internal combustion engine, a compressor and a pump, whereas the inner bearing part is formed by a bearing ring of the cam shaft.

29. The sliding bearing arrangement according to claim 21 wherein the shaft forms a Lanchester balancer of an internal combustion engine, whereas the inner bearing part is formed by a bearing ring of the Lanchester balancer.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0029] Additional details, characteristics and advantages of the subject of the invention are disclosed in the sub-claims and the following description of the respective figures, which show a preferred embodiment in an exemplary fashion of the subject matter according to the invention in conjunction with the accompanying figures, in which

[0030] FIG. 1 shows a cross sectioned side view of a sliding bearing arrangement which is embodied in a crank drive of an internal combustion engine,

[0031] FIG. 2a shows an axial view of an inner bearing part which is embodied as a pin bearing journal of a crank drive with two recess areas applied in the surface,

[0032] FIG. 2b shows a side view of the pin bearing journal according to FIG. 2a,

[0033] FIG. 3 shows an axial view of a sliding bearing arrangement with an inner bearing part and an outer bearing part, where the inner bearing part features two recess areas in the surface, formed by a continuous varying radius,

[0034] FIG. 4 shows another embodiment of inner bearing parts forming bearing rings on a cam shaft and

[0035] FIG. 5 shows yet another embodiment of inner bearing parts forming bearing rings on the shaft of a Lanchester balancer.

DETAILED DESCRIPTION

[0036] FIG. 1 shows an embodiment of a sliding bearing arrangement 1 for supporting a shaft 10 in a support element 11, and the arrangement 1 comprises an inner bearing part 12 with a sliding surface 13 and an outer bearing part 14 with a sliding surface 15. The sliding bearing arrangement 1 is embodied as a bearing arrangement in a crank drive, and the shaft 10 forms a crank shaft 21, and thus the inner bearing part 12 forms a journal 23 of the crank shaft 21 and the outer bearing part 14 forms a connecting rod 24 for connecting the crank shaft 21 with a piston 29.

[0037] Next to the journal 23 for connecting the crank shaft 21 with the connecting rod 24, journals 22 are arranged to support the crank shaft 21 in a crank housing, what is nor shown in detail.

[0038] When the shaft 10 rotates in a rotary axis 16 the sliding surface 13 of the inner bearing part 12 performs a sliding movement relative to the sliding surface 15 of the outer bearing part 14, formed by the connecting rod 24 or e.g. as shown as in insert part of the connecting rod 24.

[0039] The journal 22 for supporting the crank shaft 21 in a crank housing and the journal 23 for connecting the crank shaft 21 to the connecting rod 24 feature at least one recess area 17 which is extending in a certain circumferential position of the surface 13 of the inner bearing part 12. In the same way, the journals 22 for supporting the crank shaft 21 in a crank housing feature recess areas 17 in the sliding surfaces 13.

[0040] The connection between the connecting rod 24 and the piston 29 comprises a piston pin 30, and the connection between the connecting rod 24 and the piston pin 30 forms another embodiment of a sliding bearing arrangement 1. In the sliding surface 13 a recess area 17 is applied, and the position of the recess area is arranged lateral to the direction of extension of the connecting rod 24.

[0041] The embodiment according to FIG. 1 shows a different sliding bearing arrangement 1, and the shaft 10 which is forming a crank shaft 21 having main bearing journals 22 and pin bearing journals 23 can feature at least one recess area as well as the piston pin 30 can feature a recess area 17 in the sliding surface 13. Each of the main bearing journal 22 and the pin bearing journal 23 feature a cylindrical surface 13, and the journals 22 and 23 form the inner bearing part 12 of the sliding bearing arrangement 1. The interconnection between the small eye of the connecting rod 24 and the piston 29 comprises a sliding bearing arrangement 1 with a rotary axis 16 extending parallel to the rotary axis 16 of the crank shaft 21.

[0042] FIGS. 2a and 2b show an embodiment of an inner bearing part 12 formed by a shaft 10 as a part of a sliding bearing arrangement, and the inner bearing part 12 in FIG. 2a is depicted in a view out from the direction of the rotary axis 16 and in FIG. 2b the inner bearing part 12 is depicted in view sidewise to the rotary axis 16 extending horizontally in the depiction plane. The inner bearing part 12 features a surface 13, and in the surface 13 there are two recess areas 17 located. The recess areas 17 feature an angle of extension, described with 1 and 2, and the embodiment shows 1 with a circumferential angle of 55 and 2 is shown with a circumferential angle of 95.

[0043] In FIG. 2a the top dead center TDC is depicted in the 12 o'clock position of the cross section of the inner bearing part 12, and with respect to the top depth center TDC the recesses 17 are arranged on the left and on the right side lateral to the top dead center TDC. These lateral sections, where the recess areas are applied, form low pressure sections, but in the section of the top dead center TDC and the section opposite to the top dead center TDC, the so called bottom dead center (not references in the figure), form pressure load areas 20, where the sliding surface 13 is needed to transmit high load between the inner bearing part 12 and an outer bearing part.

[0044] FIG. 2b shows the inner bearing part 12 with the recess areas 17 on the right side of the rotary axis 16 as shown in FIG. 2a, and the transition of the recess area 17 into the untreated surface 13 feature a sequence of radii 18, and effected by the sequence of radii 18 the stress concentration on the edge of the surface 13 transiting into the recess area 17 is minimized.

[0045] The recess area 17 extents over the entire width of the bearing part 12 and features a depth of e.g. 0.1 mm. The bottom surface of the recess area 17, as shown in FIG. 2a, is formed with a cylindrical surface and compared to the cylindrical surface of the untreated sliding surface 13 lateral to the recess area 17, as determined with the high pressure areas 20, the diameter of the surface is only reduced in order to extinguish the hydrodynamic pressure by increasing the clearance between the sliding partners in the tribological system. The recess area 17 can be achieved by cutting machining, etching machining, electrical discharge machining, forging, coating or any other form of material removal, material addition or plastic deformation. The clearance in between the sliding surface 13 and 15 of a sliding bearing arrangement 1 is explained in conjunction with the following FIG. 3.

[0046] FIG. 3 shows a cross section of a sliding bearing arrangement 1 for supporting a shaft 10 in a support element 11, comprising an inner bearing part 12 with a sliding surface 13 and comprising an outer bearing part 14 with a sliding surface 15. The inner bearing part 12 is formed by the shaft 10 and the outer bearing part 14 is formed by a bore in the support element 11. When the shaft 10 is rotating in a rotary axis 16 the sliding surface of the inner bearing part 12 performs a sliding movement in contact against the sliding surface 15 of the outer bearing part 14.

[0047] According to this embodiment, the recess areas 17 are formed by an area of a continuous varying radius R of the inner bearing part 12. This design of the recess areas 17 lead to an elliptic shape 19 of the inner bearing part 12. The unaffected shape of a round inner bearing part 12 is depicted with a dashed circle.

[0048] The recess areas are disposed in regions with less hydrodynamic pressure, and when the bearing arrangement 1 is stressed by the force F, this load is transmit-ted by a pressure load area 20. The recess areas 17 are arranged lateral to the pressure load area 20, whereas the load can be time-varying over the revolution of the shaft 10 in the rotary axis 16. Accordingly, the positions, where the recess areas 17 are applied, are defined with respect to the time-varying load, and the sliding bearing arrangement 1 may transfer the load between the shaft 10 and the support element 11 by pressure load areas 20, which depend on the rotation position of the shaft 10 in the support element 11. Only when the pressure load area 20 is positioned in the line of influence of the force F, the force F arises for stressing the sliding bearing arrangement 1.

[0049] Due to the distance increasing of the surface 13 of the inner bearing part 12 from the surface 15 of the outer bearing part 14, the power loss of the sliding bearing arrangement 1 due to friction in the tribological system is minimized. In the following, different applications are shown, where a sliding bearing arrangement 1 with the features of the present invention can be applied.

[0050] FIG. 4 shows a shaft 10 which is performed as a cam shaft 25 with a number of cams 31, which are arranged on the camp shaft 25.

[0051] The cam shaft 25 features bearing rings 26 which form inner bearing parts 12 of a sliding bearing arrangement according to the present invention, when the cam shaft 25 is arranged in a cylinder head of an internal combustion engine. In the surface 13 of the inner bearing parts 12 recess areas 17 are applied. The circumferential position of the recess areas 17 correlate to the rotatory position of the cams 31. The recess areas 17 are determined in rotary positions where the hydrodynamic pressure between the shown inner bearing part 12 formed by the bearing rings 26 and an outer bearing part, which can be formed by the cylinder head, is minimal.

[0052] FIG. 5 shows another embodiment of applying a sliding bearing arrangement 1 according to the present invention, and the embodiment shows a Lanchester balancer 27. The Lanchester balancer 27 forms a shaft 10 with an offset section 32, and the Lanchester balancer 27 can be applied in an internal combustion engine. In order to support the Lanchester balancer 27, bearing rings 28 are arranged on the shaft 10, and in the surface 13 of the bearing rings 28 recess areas 17 are applied.

[0053] When the Lanchester balancer 27 rotates in the rotary axis 16, an inertia force F is induced due to the offset section 32. In order to support this force with a continuous changing angle over the revolution of the Lanchester balancer 27, in the bearing rings 28 a counter-force F is induced. This counter-force F is positioned opposite to the recess areas 17, and only in the section where the counter-force F arises, the bearing ring 28 must transmit a force, and thus this position forms the pressure load area 20.

[0054] The present invention is not limited to the embodiment described above, which are represented as an example only and can be modified in various ways within the scope of protection defined by the depending patent claims.

LIST OF NUMERALS

[0055] 1 sliding bearing arrangement [0056] 10 shaft [0057] 11 support element [0058] 12 inner bearing part [0059] 13 sliding surface [0060] 14 outer bearing part [0061] 15 sliding surface [0062] 16 rotary axis [0063] 17 recess area [0064] 18 sequence of radii [0065] 19 elliptic shape [0066] 20 pressure load area [0067] 21 crank shaft [0068] 22 journal [0069] 23 journal [0070] 24 connecting rod [0071] 25 cam shaft [0072] 26 bearing ring [0073] 27 Lanchester balancer [0074] 28 bearing ring [0075] 29 piston [0076] 30 piston pin [0077] 31 cam [0078] 32 offset section [0079] 1 angle [0080] 2 angle [0081] R continuous varying radius [0082] F force [0083] TDC Top Dead Center