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EP-4544198-B1 - BEARING SHELL, BEARING, PISTON ENGINE AND USE OF A BEARING SHELL

EP4544198B1EP 4544198 B1EP4544198 B1EP 4544198B1EP-4544198-B1

Inventors

  • HALLA-AHO, PASI
  • PERINEL, Luciano
  • ISTOLAHTI, Jaakko
  • LEPPÄKANGAS, Janne Joonas
  • VESALA, Jukka-Pekka

Dates

Publication Date
20260506
Application Date
20220622

Claims (15)

  1. A bearing shell (1) for a bearing (3) that connects a connecting rod (4) of a piston engine to a crankshaft (5), the inner surface of the bearing shell (1) being provided with an oil groove (10), the oil groove (10) com-5 prising a first portion (11), and a second portion (12) said bearing shell being characterized in that a third, intermediate portion (13) connects the first portion (11) and the second portion (12), wherein the first portion (11) and the second portion (12) are straight and run in the circumferential direction of the bearing shell (1), and wherein the third portion (13) is narrower than the first portion (11) and the second portion (12), and at least part of the third portion (13) runs in a direction that deviates in an axial direction of the bearing shell (1) from the circumferential direction of the bearing shell (1) towards a side of the bearing shell (1).
  2. A bearing shell (1) according to claim 1, wherein the third portion (13) is arranged between the imaginary extensions of the edges of the first portion (11) and the second portion (12), or wherein the third portion (13) extends from said imaginary extensions in the axial direction of the bearing shell (1) towards the sides of the bearing shell (1) at most a distance corresponding to the width of the first portion (11) and the second portion (12).
  3. A bearing shell (1) according to claim 1 or 2, wherein the third portion (13) does not extend in the axial direction of the bearing shell (1) beyond the imaginary extensions of the edges of the first portion (11) and the second portion (12) and/or wherein the third portion (13) is configured so that on each imaginary line drawn from the first portion (11) to the second portion (12) on the inner surface of the bearing shell (1) in the circumferential direction, there is at least one section that is outside the third portion (13) of the oil groove (10).
  4. A bearing shell (1) according to any of the preceding claims, wherein the third portion (13) extends in the circumferential direction of the bearing shell (1) over an angle of 40-100 degrees and/or wherein the third portion (13) is arranged in the circumferential direction in the middle of the bearing shell (1).
  5. A bearing shell (1) according to any of the preceding claims, wherein the width of the first portion (11) and the second portion (12) is 15-30 percent of the width of the bearing shell (1) and/or wherein the width of the third portion (13) is 20-60 percent of the width of the first portion (11) and the second portion (12).
  6. A bearing shell (1) according to any of the preceding claims, wherein the oil groove (10) is arranged in the axial direction of the bearing shell (1) in the middle of the bearing shell (1).
  7. A bearing shell (1) according to any of the preceding claims, wherein the first portion (11) extends in the circumferential direction to a first end of the bearing shell (1) and the second portion (12) extends to a second end of the bearing shell (1).
  8. A bearing shell (1) according to any of the preceding claims, wherein each of the first portion (11) and the second portion (12) is provided with at least one oil hole (14) and/or wherein the third portion (13) does not comprise any holes.
  9. A bearing shell (1) according to any of the preceding claims, wherein the bearing shell (1) has a substantially semicircular shape.
  10. A bearing shell (1) according to any of the preceding claims, wherein at least part of the third portion (13) has a zigzag shape and/or wherein at least part of the third portion (13) has a serpentine shape.
  11. A bearing shell (1) according to any of claims 1-9, wherein the third portion (13) is straight.
  12. A bearing (3) for connecting a connecting rod (4) of a piston engine to the crankshaft (5) of the engine, wherein the bearing (3) comprises a bearing shell (1) according to any of the preceding claims.
  13. A bearing (3) according to claim 12, wherein said bearing shell (1) forms a lower half of the bearing (3), and the upper half of the bearing (3) is formed by a bearing shell (2) comprising no oil groove or an oil groove extending only over part of the bearing shell (2) in the circumferential direction.
  14. A piston engine comprising a crankshaft (5), a connecting rod (4) and a bearing (3) connecting the connecting rod (4) to the crankshaft (5), wherein the bearing (3) is a bearing (3) according to claim 12 or 13.
  15. The use of the bearing shell (1) according to any of claims 1-11 as a lower half of a bearing (3) that connects a connecting rod (4) of a piston engine to a crankshaft (5).

Description

Technical field of the invention The present invention concerns a bearing shell for a bearing that connects a connecting rod of a piston engine to a crankshaft, as defined in claim 1. The invention also concerns a bearing, a piston engine and a use of a bearing shell. Background of the invention In a piston engine, a piston rod connects each piston to a crankshaft. The bearing connecting the piston rod to the crankshaft is often referred to as a big end bearing. A typical big end bearing is a slide bearing comprising two halves that are arranged around a crankpin of the crankshaft. The bearing is rotationally fixed to the connecting rod and there is thus a rotational movement between the crankpin and the bearing. An oil film is formed between the inner surface of the bearing and the crankpin. Typically this type of bearing can be seen in EP 3 401 560 A1 (Volvo). Often the lower half of the big end bearing is provided with an oil groove. The upper half of the bearing may have a level surface. The purpose of the oil groove is to facilitate spreading of lubricating oil on the bearing surface. The oil groove runs in the circumferential direction of the bearing in the middle of the bearing surface. Figure 3 shows an example of the lower half of a prior art big end bearing. During use of the engine, the crankpin wears. However, the wear is not even. The crankpin wears more at the area that forms a lower part of the crankpin when the piston is at top dead center, as shown in figure 1. Even the lower part of the crankpin does not wear uniformly, but the area aligned with the oil groove of the bearing experiences less wear than the areas on either side of the oil groove. Due to the uneven wear, a protruding portion, i.e. a ridge can be formed in the middle of the crankpin. The height of the ridge can correspond to the thickness of the oil film. An exaggerated view of such a ridge in shown in the enlarged views of figures 1 and 2. When the piston is around bottom dead center, as in the situation shown in figure 2, the ridge of the crankpin is in contact with the upper half of the bearing, which can cause problems, such as overloading and local wear of the upper half of the bearing. Problems can be encountered also after a new bearing has been changed at overhaul, because the protruding portion of the crankpin contacts a non-worn bearing surface and causes uneven loading. Summary of the invention An object of the present invention is to provide an improved bearing shell for a bearing that connects a connecting rod of a piston engine to a crankshaft. The characterizing features of the bearing shell according to the invention are given in claim 1. Other objects of the invention are to provide an improved bearing, a piston engine and a use of a bearing shell. The inner surface of the bearing shell according to the invention is provided with an oil groove, the oil groove comprising a first portion, a second portion and a third, intermediate portion connecting the first portion and the second portion, wherein the first portion and the second portion are straight and run in the circumferential direction of the bearing shell, and wherein the third portion is narrower than the first portion and the second portion and at least part of the third portion runs in a direction that deviates in an axial direction of the bearing shell from the circumferential direction of the bearing shell. Because of the narrower groove, larger part of the bearing shell is in contact with the crankpin and the crankpin wears more uniformly. Because the direction of the third portion differs from the circumferential direction, continuous non-contact portions in the circumferential direction of the bearing shell can be reduced. This reduces forming of a ridge at the area of the oil groove. According to an embodiment of the invention, the third portion is arranged between the imaginary extensions of the edges of the first portion and the second portion, or the third portion extends from said imaginary extensions in the axial direction of the bearing shell towards the sides of the bearing shell at most a distance corresponding to the width of the first portion and the second portion. This ensures that the third portion does not disturb forming of the oil film on the bearing surface. According to an embodiment of the invention, the third portion does not extend in the axial direction of the bearing shell beyond the imaginary extensions of the edges of the first portion and the second portion. The third portion does thus not broaden the area of the oil groove in the axial direction. According to an embodiment of the invention, the third portion is configured so that on each imaginary line drawn from the first portion to the second portion on the inner surface of the bearing shell in a circumferential direction, there is at least one section that is outside the third portion of the oil groove. There is thus no area on the outer surface of the crankpin that