EP2981691B1

EP2981691B1 - Oil sump and oil sump arrangement

Info

Publication number: EP2981691B1
Application number: EP14715035.3A
Authority: EP
Inventors: Federico BRIGHI; Odorico Contento; Massimo CATTARINUSSI
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2013-04-05
Filing date: 2014-03-13
Publication date: 2018-05-02
Anticipated expiration: 2034-03-13
Also published as: FI126116B; KR20150140731A; KR102134499B1; FI20135329A; EP2981691A1; CN105378239B; WO2014162047A1; CN105378239A

Description

Technical field of the invention

The present invention relates to an oil sump for a piston engine in accordance with the preamble of claim 1. The invention also concerns an oil sump arrangement according to the preamble of the other independent claim.

Background of the invention

Oil sumps of internal combustion engines can be either wet sumps or dry sumps. The main function of a wet sump is to be an oil reservoir for the engine. In dry sump designs, the engine is provided with a separate oil reservoir, into which the oil is introduced from the oil sump. In addition to the main function of the oil sump as an oil collector and reservoir, the oil sump is in many engines an important part of the whole engine structure. Cracks and other problems in the oil sump are very difficult to detect while the engine is in use, and therefore the design must be robust. In many large internal combustion engines, such as in ship or power plant engines, oil sumps are attached to the engine blocks by means of support beams, which are arranged on the upper surfaces of the side walls of the oil sumps. On the sides of the oil sumps, the support beams are welded together with transversal partition walls, which divide the oil sump into compartments. The weld seams between the partition walls and the support beams are subjected to very high fatigue stress, which is mainly a result of the vibrations and displacements of the engine block. Therefore, a very high quality of the weld seams is required. Also some additional treatment of the weld seams may be needed in order to ensure sufficient resistance against failures. All this increases the costs of the construction.
JP 2010 174655 A discloses an oil pan, which is divided into a main chamber and an auxiliary chamber by ribs. The oil pan is made of resin and connected to an engine by means of a flange that is part of the peripheral wall of the oil pan.
JP S62 16711 U discloses an oil pan that is divided into compartments by means of straight partition walls.
US 2010/031915 A1 discloses an oil pan comprising a baffle defining a first oil reservoir and a second oil reservoir. The baffle is lower than the sidewalls of the oil pan.
JP S60 21514 U discloses an oil pan comprising a plurality of partition walls. A flange is attached to the peripheral wall of the oil pan so that it extends outwards from the peripheral wall. The partition walls are lower than the peripheral wall.

Summary of the invention

An object of the present invention is to provide an improved oil sump for a piston engine. The characterizing features of the oil sump according to the invention are given in the characterizing part of claim 1. Characterizing features of the oil sump arrangement are given in the characterizing part of the other independent claim.
An oil sump according to the invention comprises a bottom plate, side walls and end walls encircling the bottom plate, and at least one partition wall, which partition wall is arranged between the side walls of the oil sump for dividing the oil sump into compartments. Both ends of the partition wall are provided with a curvilinear cutting opening towards the longitudinal center line of the oil sump.
An oil sump arrangement according to the invention comprises an oil sump defined above. The arrangement is provided on both sides of the oil sump with a support beam for fastening the oil sump to an engine block, which support beam is arranged above the partition wall and fastened to the partition wall by a weld.
Because of the curvilinear cuttings of the partition walls, stresses in the welds that are used for fastening the oil sump to the engine block can be reduced. Lower quality of the welds is thus required and no additional treatments are needed for increasing the strength of the welds. This helps to reduce manufacturing costs.
According to an embodiment of the invention, each end of the partition wall is provided with a protrusion extending away from the bottom plate, and the cuttings are arranged in the protrusions. According to another embodiment of the invention, at least part of the cutting is a segment or a sector of a circle, of which radius is 1.5-2.5 times the thickness of the partition wall. Preferably the radius is 1.8-2.2 times the thickness of the partition wall.
According to an embodiment of the invention, the height of the weld in the oil sump arrangement is 0.5-1.5 times the thickness of the partition wall. Preferably, the height of the weld is 0.8-1.2 times the thickness of the partition wall. According to another embodiment of the invention, the support beam extends over the weld towards the center line of the oil sump a distance, which is 0.5-1.5 times the thickness of the partition wall. Preferably the distance is 0.8-1.2 times the thickness of the partition wall.

Brief description of the drawings

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

Fig. 1 shows an oil sump according to the invention in connection with an engine block,
Fig. 2 shows a cross-sectional view of the oil sump of figure 1,
Fig. 3 shows an enlarged view of a detail of the oil sump, and
Fig. 4 shows dimensioning of the detail of figure 3.

Description of embodiments of the invention

In figure 1 is shown an oil sump 1 according to an embodiment of the invention in connection with the engine block 11 of an internal combustion engine 10. The engine 10 is a large piston engine, which could be used, for instance, as a main or an auxiliary engine of a ship or at a power plant for producing electricity. In the example of the figures, the cylinders 12 of the engine 10 are arranged in a V-configuration, but also other cylinder configurations could be used. In the embodiment of the figures, the oil sump 1 is a wet sump 1. In a wet sump design, the crankcase 13 of the engine 10 is used as a reservoir for oil. However, the invention is also applicable to dry sump constructions, in which external oil reservoirs are used.
In figure 2 is shown a cross-sectional view of the oil sump 1 of figure 1. The oil sump 1 is a trough-shaped part, which can accommodate a relatively large amount of oil. The oil sump 1 comprises a bottom plate 2, which is encircled by a first and a second side wall 3a, 3b and a first and a second end wall 4a, 4b. In the embodiment of the figures, the bottom plate 2 comprises a straight middle section 2a and inclined side sections 2b, 2c. The side sections 2b, 2c are further divided into two sections so that the outer of the two sections is inclined more than the inner section in relation to the horizontal plane. The bottom plate 2 is thus bent and rises towards the sides of the oil sump 1, which helps to collect the oil towards the middle of the oil sump 1. The bottom plate 2 can be made of one or several pieces. It is also possible that the side walls 3a, 3b are integrated into the same part as the bottom plate 2 or part of it. In the embodiment of the figures, the side walls 3a, 3b are inclined slightly outwards. However, they could also be straight, i.e. at right angle relative to the horizontal plane. For restricting oil flow inside the oil sump 1 in the longitudinal direction of the oil sump 1, the oil sump 1 is provided with partition walls 5, which divide the oil sump 1 into compartments 7. Each partition wall 5 extends from the first side wall 3a to the second side wall 3b. The height of the partition wall 5 increases slightly towards the sides of the oil sump 1. Because of the varying height of the partition walls 5 and the inclined side sections 2b, 2c of the bottom plate 2, the upper edges of the partition walls 5 are inclined in relation to the horizontal plane. The sidewall ends of the partition walls 5 are further provided with protrusions 5b, which extend away from the horizontal plane. The protrusions 5b thus increase the height of the partition wall 5 at the ends at the partition wall 5. The partition walls 5 are provided with openings 9 for allowing oil flow between compartments 7 and for accommodating pipes that are arranged in the oil sump 1 for different purposes. The partition wall 5 can be made of a single piece of material, or it can be composed of several parts. The partition walls 5 could also be integral parts of an oil sump casting.
The oil sump 1 is fastened to the engine block 11 by means of support beams 6a, 6b, 6c, 6d, which are arranged between the oil sump 1 and the engine block 11. Each end and side of the engine 10 is provided with a support beam 6a, 6b, 6c, 6d. The support beams 6a, 6b, 6c, 6d are fastened to the oil sump 1 by welding. On the sides of the oil sump 1, welds 12 are arranged between the support beams 6a, 6b and the protrusions 5b of the partition walls 5. To decrease the stress, which is caused by vibrations and engine block displacements acting on the welds 12 between each partition wall 5 and the support beam 6a, 6b, each partition wall 5 is provided with a curvilinear cutting 5a at both ends of the partition wall 5. The cutting 5a is arranged in the protrusion 5b and opens towards the longitudinal center line 8 of the oil sump 1. Figure 4 shows an enlarged view of the cutting 5a. The cutting 5a is a segment of a circle. The radius R of the circle is 1.5-2.5 times the thickness of the partition wall 5, preferably approximately two times, for instance 1.8-2.2 times the thickness of the partition wall 5. Preferably the distance of the bottom, i.e. the outermost part of the cutting 5a, is at least 1.5 times the radius R of the circle from the end of the partition wall 5. As can be seen in figure 4, the width of the support beam 6a is greater than the width of the protrusion 5b of the partition wall 5 and the length of the weld 12 between the support beam 6a and the partition wall 5. The length of the weld 12 is approximately the same as the width of the protrusion 5b. The support beam 6a extends a distance X over the inner edge of the protrusion 5b. Correspondingly, the weld 12 extends to the same distance X from the inner edge of the support beam 6a. The distance X is 0.5-1.5 times the thickness of the partition wall 5. Preferably the distance X is approximately the same as thickness of the partition wall 5, for instance 0.8-1.2 times the thickness of the partition wall 5. The height H of the weld 12 is 0.5-1.5 times the thickness of the partition wall 5. Preferably the height H is approximately the same as thickness of the partition wall 5, for instance 0.8-1.2 times the thickness of the partition wall 5. The design of the partition wall 5 and the construction of the oil sump assembly help to reduce the stress of the weld seam. Because of this, the required quality of the welds 12 is lower than in prior art constructions, and the welding can be carried out by a less skilled welder. In addition, costly additional treatments for increasing the strength of the welds 12 are not needed.
It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may vary within the scope of the appended claims.

Claims

An oil sump arrangement for a piston engine (10), the oil sump arrangement comprising an oil sump (1), which oil sump (1) comprises a bottom plate (2), side walls (3a, 3b) and end walls (4a, 4b) encircling the bottom plate (2) and at least one partition wall (5), which partition wall (5) is arranged between the side walls (3a, 3b) of the oil sump (1) for dividing the oil sump (1) into compartments (7), each end of the partition wall (5) being provided with a protrusion (5b) extending away from the bottom plate (2), the arrangement further comprising, on both sides of the oil sump (1), a support beam (6a, 6b) for fastening the oil sump (1) to an engine block (11), which support beam (6a, 6b) is arranged above the partition wall (5), characterized in that the support beam (6a, 6b) is fastened to the partition wall (5) by a weld (12), each sidewall end of the partition wall (5) is provided with a curvilinear cutting (5a) that is arranged in the protrusion (5b) and opens towards the longitudinal center line (8) of the oil sump (1), at least part of the cutting (5a) being a segment or a sector of a circle, of which radius (R) is 1.5-2.5 times the thickness of the partition wall (5).
An oil sump arrangement according to claim 1, characterized in that the radius (R) is 1.8-2.2 times the thickness of the partition wall (5).
An oil sump arrangement according to claim 1 or 2, characterized in that the height of the weld (12) is 0.5-1.5 times the thickness of the partition wall (5).
An oil sump arrangement according to claim 3, characterized in that the height of the weld (12) is 0.8-1.2 times the thickness of the partition wall (5).
An oil sump arrangement according to any of the preceding claims, characterized in that the support beam (6a, 6b) extends over the weld (12) towards the center line (8) of the oil sump (1) a distance (X), which is 0.5-1.5 times the thickness of the partition wall (5).
An oil sump arrangement according to claim 5, characterized in that the distance (X) is 0.8-1.2 times the thickness of the partition wall (5).