Bearing element, radial bearing and piston engine

Abstract

The bearing element (1) for a radial bearing of a piston engine has an inner circumferential surface configured to form at least part of a bearing surface and an outer circumferential surface, the bearing element comprising an oil feeding hole (2) extending from the outer surface to the inner surface for feeding lubrication oil onto the inner surface, wherein the outer surface of the bearing element is provided with at least one recessed area (3) arranged apart from the oil feeding hole and configured to spread lubrication oil onto the outer surface of the bearing element in case the bearing element rotates relative to a part facing the outer circumferential surface of the bearing element.

Description

[0001] Bearing element, radial bearing and piston engine

[0002] Technical field of the invention

[0003] The present invention concerns a bearing element for a radial bearing of a piston engine, as defined in claim 1 . The invention also concerns a radial bearing for a piston engine and a piston engine.

[0004] Background of the invention

[0005] Large piston engines, such as ship and power plant engines, comprise slide bearings for rotatably supporting various parts of the engine. For instance, the crankshaft and camshaft are supported against an engine block by slide bearings. A typical slide bearing comprises a bearing shell having an inner circumferential surface forming a bearing surface. Lubrication oil is introduced onto the bearing surface to form an oil film between the bearing surface and the part rotating against the bearing surface. The bearing shell is stationary arranged within a housing or another part supporting the bearing shell. The bearing shell is thus not supposed to move relative to the surrounding parts. However, in an abnormal situation, such as a bearing seizure, the bearing shell may start to rotate relative to the surrounding parts. If such a situation is not detected quickly and the engine is not shut down, that may cause severe damage to the components of the engine.

[0006] Summary of the invention

[0007] An object of the present invention is to provide an improved bearing element for a radial bearing of a piston engine. Another object of the invention is to provide an improved radial bearing for a piston engine. A still further object of the invention is to provide an improved piston engine.

[0008] The bearing element according to the invention has an inner circumferential surface configured to form at least part of a bearing surface and an outer circumferential surface, the bearing element comprising an oil feeding hole extending from the outer surface to the inner surface for feeding lubrication oil onto the inner surface, wherein the outer surface of the bearing element is provided with at least one recessed area arranged apart from the oil feeding hole and configured to spread lubrication oil onto the outer surface of the bearing element in case the bearing element rotates relative to a part facing the outer circumferential surface of the bearing element.

[0009] During normal operation of the bearing, the recessed area does not affect functioning of the bearing. However, if the bearing element in an abnormal situation starts to rotate relative to the surrounding parts, the recessed area is filled with lubrication oil and the lubrication oil is spread onto the outer surface of the bearing element. This reduces friction between the bearing element and the surrounding parts and helps avoiding severe damage to the bearing. A need for a sudden engine shutdown may thus be avoided.

[0010] According to an embodiment of the invention, the recessed area extends in the axial direction of the bearing element over at least 70 percent of the width of the bearing element. A wide recessed area ensures that the lubrication oil is effectively spread over a major part of the outer surface of the bearing element.

[0011] According to an embodiment of the invention, the distance between the oil feeding hole and the recessed area in the circumferential direction of the bearing element is at most 45 degrees. By arranging the recessed area close to the oil feeding hole, the recessed area is brought in case of rotation of the bearing element quickly into fluid communication with an oil supply line supplying lubrication oil to the oil feeding hole, thus ensuring that lubrication oil is promptly spread onto the outer surface of the bearing element.

[0012] According to an embodiment of the invention, the outer surface of the bearing element is provided with two or more recessed areas arranged apart from the oil feeding hole. By providing the bearing element with two or more recessed areas, the lubrication oil is effectively spread over the whole outer surface of the bearing element.

[0013] According to an embodiment of the invention, the recessed areas are arranged symmetrically about the oil feeding hole.

[0014] According to an embodiment of the invention, the outer surface of the bearing element is provided with two recessed areas and the distance between the recessed areas is 180 degrees in the circumferential direction of the bearing element. According to an embodiment of the invention, the outer surface of the bearing element is plain outside the oil feeding hole and the recessed area(s).

[0015] According to an embodiment of the invention, the bearing element is a bushing. The bearing can thus comprise a single bearing element extending over a full circle. The inner circumferential surface of the bearing element thus forms the whole bearing surface.

[0016] According to an embodiment of the invention, the bearing element is configured to form part of a half-shell bearing. Instead of being a bushing, the bearing element can thus extend over an angle of approximately 180 degrees. The bearing surface of the bearing is thus formed by the inner circumferential surfaces of two bearing elements.

[0017] According to an embodiment of the invention, the bearing element is configured to support a camshaft or crankshaft.

[0018] The radial bearing according to the invention for a piston engine comprises one or more bearing elements, each bearing element having an inner circumferential surface configured to form at least part of a bearing surface and an outer circumferential surface, the bearing comprising an oil feeding hole extending from the outer surface of one of said one or more bearing elements to the inner surface of said bearing element for feeding lubrication oil onto the bearing surface, wherein the outer surface of at least one of said one or more bearing elements is provided with at least one recessed area arranged apart from the oil feeding hole of the bearing and configured to spread lubrication oil onto the outer surface of the bearing element in case the bearing element rotates relative to a part facing the outer circumferential surface of the bearing element.

[0019] The piston engine according to the invention comprises a radial bearing defined above.

[0020] According to an embodiment of the invention, the radial bearing supports a camshaft or crankshaft of the engine. Brief description of the drawinqs

[0021] Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which

[0022] Fig. 1 shows a bearing element according to an embodiment of the invention.

[0023] Detailed description of embodiments of the invention

[0024] Figure 1 shows a bearing element according to an embodiment of the invention. The bearing element 1 can be used in a bearing of a large piston engine. The expression large piston engine refers here to an engine having a cylinder diameter of at least 150 mm. The engine could be, for instance, a main or an auxiliary engine of a ship or a power plant engine. The bearing element 1 is configured to form part of a slide bearing. The bearing can be, for instance, a camshaft bearing that is configured to support a camshaft of the engine against an engine block.

[0025] The bearing element 1 can be arranged within a bearing housing or it can be surrounded by other parts supporting the bearing element 1 . The bearing element 1 has an inner circumferential surface and an outer circumferential surface. The inner circumferential surface is configured to function as a bearing surface. The inner circumferential surface is thus configured to support a part rotating relative to the bearing element 1 .

[0026] The bearing element 1 comprises an oil feeding hole 2 extending from the outer circumferential surface to the inner surface. Via the oil feeding hole 2, lubrication oil can be fed onto the inner surface of the bearing element 1 . An oil film is thus formed between the bearing surface and the part rotating against bearing element 1 such that direct contact between the surfaces of the bearing element 1 and the rotating part is prevented. The bearing element 1 could comprise two or more oil feeding holes 2.

[0027] The outer surface of the bearing element 1 is provided with at least one recessed area 3 arranged apart from the oil feeding hole 2. The recessed area 3 is configured to spread lubrication oil onto the outer surface of the bearing element 1 in case the bearing element 1 rotates relative to a part facing the outer circumferential surface of the bearing element 1 . The part facing the outer circumferential surface of the bearing element 1 can be, for instance, a bearing housing. During normal operation of the bearing, the bearing element 1 is stationary relative to the bearing housing. In an abnormal situation, such as a bearing seizure, the bearing element 1 may start to rotate relative to the bearing housing. If the bearing element 1 starts rotating within the bearing housing, the recessed area 3 is filled with lubrication oil and the oil is spread onto the outer surface of the bearing element 1 . The lubrication oil reduces friction between the bearing element 1 and the bearing housing. This helps avoiding immediate destruction of the bearing, and severe damage to the engine may be avoided.

[0028] In the embodiment of figure 1 , the recessed area 3 extends in the axial direction of the bearing element 1 over almost the whole width of the bearing element 1 . This ensures that the lubrication oil is effectively spread over the whole width of the bearing element 1 . Preferably, the recessed area 3 extends in the axial direction of the bearing element 1 over at least 70 percent of the width of the bearing element 1 .

[0029] In the embodiment of figure 1 , the recessed area 3 is arranged in the circumferential direction of the bearing element 1 at a distance of approximately 20 degrees from the oil feeding hole 2. By arranging the recessed area close to the oil feeding hole 2, in case of rotation of the bearing element 1 , the recessed area 3 is brought quickly into fluid communication with an oil supply line supplying lubrication oil to the oil feeding hole 2. Prompt supply of lubrication oil onto the outer surface of the bearing element 1 is thus ensured. Preferably, the distance between the oil feeding hole 2 and the recessed area 3 in the circumferential direction of the bearing element is at most 45 degrees.

[0030] In the embodiment of figure 1 , the bearing element 1 comprises only one recessed area 3 on the outer surface. The outer surface of the bearing element 1 is plain outside the oil feeding hole 2 and the recessed area 3.

[0031] The outer surface of the bearing element 1 could be provided with two or more recessed areas arranged apart from the oil feeding hole 3. By providing the outer surface of the bearing element 1 with two or more recessed areas 3, it can be ensured that the lubrication oil is spread evenly on the outer surface over the whole circumference of the bearing element 1 . If the bearing element 1 is provided with two recessed areas 3, the recessed areas 3 can be arranged on opposite sides of the bearing element 1 . The distance between the recessed areas 3 can thus be 180 degrees in the circumferential direction of the bearing element 1 . If the bearing element 1 is provided with two or more recessed areas 3, the recessed areas 3 can be arranged symmetrically about the oil feeding hole 2.

[0032] In the embodiment of figure 1 , the bearing element 1 is a bushing and a single bearing element 1 thus forms the whole bearing surface of a bearing. The bearing element 1 has thus a circular shape extending over an angle of 360 degrees. However, instead of being a bushing, the bearing element could be configured to form part of a half-shell bearing. The bearing element 1 could thus have a semicircular shape, i.e. the bearing element 1 could extend over approximately 180 degrees. A bearing surface could be formed by the inner surfaces of two bearing elements 1 . Such a bearing could be used, for instance, as a main bearing of a piston engine to support the crankshaft.

[0033] If the bearing element 1 forms part of a half-shell bearing, the oil feeding hole 2 and the recessed area 3 do not need to be in the same bearing element 1 , but one of the bearing elements 1 of the bearing could be provided with the oil feeding hole 2 and the other bearing element 1 could be provided with the recessed area 3. If the bearing comprises two or more recessed areas 3, all the recessed areas 3 could be arranged in the same bearing element 1 , or each bearing element 1 could be provided with at least one recessed area 3. If the bearing comprises two or more oil feeding holes 2, all the oil feeding holes 2 could be arranged in the same bearing element 1 , or both bearing elements 1 could be provided with at least one oil feeding hole 2.

[0034] The bearing element 1 can be made of, for instance, a copper-based material, such as tin-bronze, aluminium-bronze, lead-bronze or bismuth-bronze.

Claims

Claims:1 . A bearing element (1 ) for a radial bearing of a piston engine, the bearing element (1 ) having an inner circumferential surface configured to form at least part of a bearing surface and an outer circumferential surface, the bearing element (1 ) comprising an oil feeding hole (2) extending from the outer surface to the inner surface for feeding lubrication oil onto the inner surface, wherein the outer surface of the bearing element (1 ) is provided with at least one recessed area (3) arranged apart from the oil feeding hole (2) and configured to spread lubrication oil onto the outer surface of the bearing element (1 ) in case the bearing element (1 ) rotates relative to a part facing the outer circumferential surface of the bearing element (1 )-2. A bearing element (1 ) according to claim 1 , wherein the recessed area (3) extends in the axial direction of the bearing element (1 ) over at least 70 percent of the width of the bearing element (1 ).

3. A bearing element (1 ) according to claim 1 or 2, wherein the distance between the oil feeding hole (2) and the recessed area (3) in the circumferential direction of the bearing element (1 ) is at most 45 degrees.

4. A bearing element (1 ) according to any of claims 1 to 3, wherein the outer surface of the bearing element (1 ) is provided with two or more recessed areas (3) arranged apart from the oil feeding hole (2).

5. A bearing element according to claim 4, wherein the recessed areas (3) are arranged symmetrically about the oil feeding hole (2).

6. A bearing element according to claim 4 or 5, wherein the outer surface of the bearing element (1 ) is provided with two recessed areas (3) and the distance between the recessed areas (3) is 180 degrees in the circumferential direction of the bearing element (1 ).

7. A bearing element (1 ) according to any of the preceding claims, wherein the outer surface of the bearing element (1 ) is plain outside the oil feeding hole (2) and the recessed area(s) (3).

8. A bearing element (1 ) according to any of the preceding claims, wherein the bearing element (1 ) is a bushing.

9. A bearing element (1 ) according to any of claims 1 to 7, wherein the bearing element (1 ) is configured to form part of a half-shell bearing.

10. A bearing element (1 ) according to any of the preceding claims, wherein the bearing element (1 ) is configured to support a camshaft or crankshaft.

11. A radial bearing for a piston engine, the bearing comprising one or more bearing elements (1 ), each bearing element (1 ) having an inner circumferential surface configured to form at least part of a bearing surface and an outer circumferential surface, the bearing comprising an oil feeding hole (2) extending from the outer surface of one of said one or more bearing elements (1 ) to the inner surface of said bearing element (1 ) for feeding lubrication oil onto the bearing surface, wherein the outer surface of at least one of said one or more bearing elements (1 ) is provided with at least one recessed area (3) arranged apart from the oil feeding hole (2) of the bearing and configured to spread lubrication oil onto the outer surface of the bearing element (1 ) in case the bearing element (1 ) rotates relative to a part facing the outer circumferential surface of the bearing element (1 ).

12. A piston engine comprising a radial bearing according to claim 11 .

13. A piston engine according to claim 12, wherein the radial bearing supports a camshaft or crankshaft of the engine.

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