PISTON OF AN INTERNAL ENGINE

Description

[0001] The invention relates to a piston of an internal combustion engine according to the preamble of claim 1 or according to the preamble of claim 6.

[0002] From DE 35 18 721 C2, a piston for an internal combustion engine is known, comprising a piston crown and a piston crown, which are preferably screwed together. A piston pin is mounted in the piston crown, the piston pin serving to connect the piston to a connecting rod of the internal combustion engine. The piston according to DE 35 18 721 C2 is oil-cooled, wherein a first, inner cooling chamber for cooling oil and a second, outer cooling chamber for cooling oil are formed between the piston crown and the piston crown, and wherein the inner cooling chamber is connected to the outer cooling chamber via at least one transfer bore. To introduce cooling oil into the inner cooling chamber, a supply bore for cooling oil is integrated into the connecting rod according to this prior art, wherein the cooling oil can be transferred from the connecting rod into the inner cooling chamber by means of a multi-part cooling oil guide sleeve.According to DE 35 18 721 C2, a first, neck-like part of the cooling oil guide sleeve is fixedly fixed in the piston base. A funnel-shaped, movable part of the cooling oil guide sleeve interacts with this fixed, neck-like part in such a way that a spring element, acting between the two parts of the cooling oil guide sleeve, resiliently presses the funnel-shaped part into sliding contact with a connecting rod head. The use of such spring-loaded cooling oil guide sleeves for transferring the cooling oil from the bore in the connecting rod to the inner cooling chamber is disadvantageous because the installation of such cooling oil guide sleeves is very complex. Furthermore, the separate spring elements cause high frictional forces between the cooling oil guide sleeve and the connecting rod.

[0003] From DE 10 2013 002 232 A1, a piston for an internal combustion engine is known in which the cooling oil guide sleeve is designed as a slotted sleeve that presses against a support surface of the piston base with a spring-like action. According to this prior art, the cooling oil guide sleeve of the piston, designed as a slotted sleeve, is formed in one piece and presses against the piston base with a spring-like action, so that a separate spring element can be dispensed with.

[0004] CN 205 013 072 U discloses a two-part piston with a cooling oil guide sleeve, wherein a circumferential groove for a seal is provided in the support surface of the piston lower part.

[0005] There is a need to further improve the functionality of a cooled piston in an internal combustion engine.

[0006] Based on this, the present invention aims to create a novel piston for an internal combustion engine.

[0007] According to a first aspect of the invention, this problem is solved by a piston according to claim 1. According to this claim, at least one circumferential groove is provided in the guide surface of the cooling oil guide sleeve and / or in the support surface of the piston lower part. Furthermore, the cooling oil guide sleeve is designed as a slotted sleeve with a slot extending in the axial direction.

[0008] According to a second aspect of the invention, this problem is solved by a piston according to claim 5. According to this claim, at least one circumferentially limited oil pocket is provided in the guide surface of the cooling oil guide sleeve and / or in the support surface of the piston lower part.

[0009] Both aspects of the invention make it possible to introduce oil for lubrication in a defined manner in the area between the guide surface of the cooling oil guide sleeve and the support surface of the piston base. This reduces or even completely eliminates friction and friction-related wear of the piston base and cooling oil guide sleeve. This improves the functionality of the cooled piston.

[0010] According to an advantageous embodiment of the first or second aspect of the invention, at least one recess, preferably at least two recesses extending radially and penetrating the cooling oil guide sleeve, is provided in the cooling oil guide sleeve, through which lubricating oil can be supplied to an area between the cooling oil guide sleeve and the piston base. This allows for a particularly advantageous supply of lubricating oil to the circumferential groove and / or the circumferentially bounded oil pocket.

[0011] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1: a partial cross-section through a first piston according to the invention in the area of ​​a cooling oil guide sleeve; Fig. 2: detail II of the Fig. 1 in the area of ​​the cooling oil guide sleeve; Fig. 3: an alternative detail of a second piston according to the invention in the area of ​​the cooling oil guide sleeve; Fig. 4: a further development of a cooling oil guide sleeve of the piston according to Fig. 2 or 3 ; Fig. 5: an alternative cooling oil guide sleeve for the piston.

[0012] The invention presented here relates to an oil-cooled piston of an internal combustion engine, in particular an internal combustion engine designed as a diesel engine or gas engine or diesel-gas engine, such as a marine diesel engine.

[0013] Such a piston is also called a diving piston.

[0014] Fig. 1 und 2 Figure 1 shows cross-sections through a first piston 12 of an internal combustion engine according to the invention in different sectional directions, wherein the piston 12 comprises a piston head 10 and a piston lower part 11. The piston head 10 and the piston lower part 11 are preferably made of a light metal, steel, or spheroidal graphite cast iron. The piston head 10 and the piston lower part 11 support each other and are preferably connected to each other by means of fastening elements designed as expansion bolts.

[0015] A piston pin (not shown) is mounted in a bore of the piston lower part 11, the piston pin serving to connect the piston to a connecting rod 13 of the internal combustion engine. The connecting rod 13 extends into Fig. 2 a so-called connecting rod head 14 is shown.

[0016] Between the piston top 10 and the piston bottom 11, a first, inner cooling chamber 15 and a second, outer cooling chamber 16 for cooling oil are formed, wherein the inner cooling chamber 15 is connected to the outer cooling chamber 16 according to Fig. 2 is connected via connecting boreholes 17.

[0017] Cooling oil, which serves to cool the piston 12, can be supplied to the piston 12, specifically to the first, inner cooling chamber 15 of the piston 12, via a bore 18 that extends through the connecting rod 13 and the connecting rod head 14. A cooling oil guide sleeve 19 interacts with the connecting rod 13 and the connecting rod head 14 of the connecting rod 13. The flow of the cooling oil is visualized by arrows 20.

[0018] The cooling oil guide sleeve 19 is designed as a slotted sleeve. A slot 21 of the cooling oil guide sleeve 19 extends in the axial direction of the piston or the cooling oil guide sleeve 19.

[0019] In its disassembled state, the cooling oil guide sleeve 19 has an outer diameter that is larger than the inner diameter of a recess in the piston base 11 into which the cooling oil guide sleeve 19 is to be inserted. To insert the cooling oil guide sleeve 19 into this recess in the piston base 11, the cooling oil guide sleeve 19 is compressed, reducing the so-called jaw width of the slot 21. After the cooling oil guide sleeve 19 is inserted into the piston base 11, a guide surface 22 of the cooling oil guide sleeve 19 presses spring-elastically against a corresponding support surface 23 of the piston base 11.

[0020] The cooling oil guide sleeve 19 is designed in one piece and is mounted in the piston lower part 11 without a separate spring element.

[0021] Preferably, the guide surface 22 of the cooling oil guide sleeve 19 and the support surface 23 of the piston lower part 11, against which the first guide surface 22 of the cooling oil guide sleeve 19 presses elastically, are contoured in a frustoconical shape. This ensures that the cooling oil guide sleeve 19 also presses elastically against a support surface 25 of the connecting rod head 14 of the connecting rod 13 with a further guide surface 24.

[0022] The preferably frustoconical guide surface 22 of the cooling oil guide sleeve 19 and the corresponding support surface 23 of the piston lower part 11 taper from one end 26 of the cooling oil guide sleeve 19 facing the connecting rod 13 in the axial direction of the piston or the cooling oil guide sleeve 19 towards an end 27 of the cooling oil guide sleeve 19 facing away from the connecting rod 13.

[0023] As already explained, after the cooling oil guide sleeve 19 is mounted in the corresponding recess in the piston base 11, the cooling oil guide sleeve 19 is spring-elastically pressed against the support surface 23 of the piston base with the guide surface 22.

[0024] Then, when the connecting rod 13 is subsequently installed, the cooling oil guide sleeve 19 is further compressed so that, due to the frustoconical contour of the guide surface 22 and the support surface 23, the cooling oil guide sleeve 19, with its further guide surface 24, presses spring-elastically against the corresponding support surface 25 of the connecting rod head 14 of the connecting rod 13. This prevents the cooling oil guide sleeve 19 from lifting off the connecting rod head 14 of the connecting rod 13 and ensures a consistently good seal between the connecting rod head 14 of the connecting rod 13 and the cooling oil guide sleeve 19.

[0025] According to the first aspect of the invention, at least one circumferential groove is provided in the preferably frustoconical, tapered guide surface 22 of the cooling oil guide sleeve 19 and / or in the correspondingly contoured support surface 23 of the piston lower part 11. Fig. 1 und 2 Figure 1 shows an embodiment in which such a groove 28 is formed exclusively in the guide surface 22 of the cooling oil guide sleeve 19. Lubricating oil can be supplied to this circumferential groove 28, in particular via the slot 21 of the slotted cooling oil guide sleeve 19, whereby the lubricating oil passes through the slot 21 and enters the groove 28 of the cooling oil guide sleeve 19. This allows a contact area between the cooling oil guide sleeve 19 and the piston lower part 11 to be lubricated in a defined manner in order to reduce friction and wear.

[0026] Fig. 3 Figure 1 shows a detail from a piston according to a second embodiment of the first aspect of the invention, in which a circumferential groove 29 is provided in the support surface 23 of the piston lower part 11. Lubricating oil can also be supplied to this groove 29 via the slot 21.

[0027] To supply the groove 28 of the exemplary embodiment of the Fig. 1, 2 or the groove 29 of the embodiment of the Fig. 3 to improve with lubricating oil is in the exemplary embodiment of the Fig. 4 At least one radially extending recess 30 penetrating the cooling oil guide sleeve 19 was provided in the cooling oil guide sleeve 19.

[0028] In Fig. 4 At least two such recesses 30 are provided in the cooling oil guide sleeve 19. Lubricating oil can be supplied to the area between the cooling oil guide sleeve 19 and the piston lower part 11 via these recesses 30; in particular, this lubricating oil can be supplied to the respective groove 28, 29 via the respective recess 30.

[0029] It should be noted here that the groove 28 can be provided in both the cooling oil guide sleeve 19 and the groove 29 in the piston base 11 simultaneously. In this case, oil can then be supplied to both grooves 28 and 29 via the recesses 30.

[0030] According to a second aspect of the present invention, it is provided that at least one circumferentially limited oil pocket 31 is provided in the preferably frustoconical contoured guide surface 22 of the cooling oil guide sleeve 19 and / or in the support surface 23 of the piston lower part 11. Fig. 5 shows a side view of a cooling oil guide sleeve 19 according to the second aspect of the invention, wherein in Fig. 5 Several circumferentially limited oil pockets 31 are incorporated into the guide surface 22 of the cooling oil guide sleeve 19.

[0031] Although not shown in the figures, such circumferentially limited oil pockets 31 can also be incorporated additionally or alternatively into the support surface 23 of the piston lower part 11.

[0032] Furthermore, it is possible to combine the first and second aspects of the invention, i.e., to use both a circumferential groove 28 and / or 29 in combination with the oil pockets 31. Any combination is conceivable.

[0033] For example, a circumferential groove 28 can be provided in the guide surface 22 of the cooling oil guide sleeve 19, and several oil pockets can be provided in the support surface 23 of the piston base 11. It is also possible to provide several circumferentially limited oil pockets 31 in the guide surface 22 of the cooling oil guide sleeve 19 and a circumferential groove 29 in the support surface 23 of the piston base 11.

[0034] Furthermore, it is also in Fig. 5 It is possible that at least one, preferably at least two, radially extending recesses 30 penetrating the cooling oil guide sleeve 19 are provided in the cooling oil guide sleeve 19, through which lubricating oil can be supplied to an area between the cooling oil guide sleeve 19 and the piston lower part 11, in particular such that the lubricating oil can be supplied to the respective oil pocket 31 via the respective recess 30.

[0035] The invention makes it possible to supply a defined contact area between the cooling oil guide sleeve 19 and the piston lower part 11 with lubricating oil in order to minimize or even completely avoid friction and wear between the cooling oil guide sleeve 19 and the piston lower part 11.

[0036] The invention is particularly applicable to pistons of large engines such as diesel engines or gas engines or diesel-gas engines in the ship sector, whose outer diameter is particularly in the range between 100 mm and 600 mm. Reference symbol list

[0037] 10 Piston top 11 Piston bottom 12 Piston 13 Connecting rod 14 Connecting rod head 15 Cooling chamber 16 Cooling chamber 17 Transfer bore 18 Bore 19 Cooling oil guide sleeve 20 Cooling oil flow 21 Slot 22 Guide surface 23 Support surface 24 Guide surface 25 Support surface 26 End 27 End 28 Groove 29 Groove 30 Recess 31 Oil pocket

Claims

1. A piston of an internal combustion engine, with a piston upper part (10), with a piston lower part (11) connected to the piston upper part (10), with a piston pin (12), which is mounted in the piston lower part (11) and serves for connecting the piston to a connecting rod (13) of the internal combustion engine, with a first cooling space (15) formed between the piston upper part (10) and the piston lower part (11) for cooling oil for cooling the piston, wherein the first cooling space (15) is connected via at least one overflow bore (17) to a second cooling space (16) formed between the piston upper part (10) and a piston lower part (11), with a cooling oil guide sleeve (19), which serves for guiding of cooling oil conducted through a bore (18) in the connecting rod (13) in the direction of the first cooling space (15), wherein a guide surface (22) of the cooling oil guide sleeve (19) adjoins a support surface (23) of the piston lower part (11), wherein at least one circumferential groove (28, 29) in the circumferential direction is introduced into the guide surface (22) of the cooling oil guide sleeve (19) and / or into the support surface (23) of the piston lower part (11), characterised in that the cooling oil guide sleeve (19) is designed as a slit sleeve with a slit (21) extending in the axial direction, which with the guide surface (22) spring-elastically presses against the support surface (23) of the piston lower part (11), wherein lubricating oil via the slit enters the respective groove (28, 29) of the cooling oil guide sleeve (19) and / or of the piston lower part (11).

2. The piston according to Claim 1, characterised in that into the cooling oil guide sleeve (19) at least one recess (30), preferentially at least two recesses (30), which extends in the radial direction and penetrates the cooling oil guide sleeve (18) is introduced, via which lubricating oil can be fed to a region between the cooling oil guide sleeve (19) and the piston lower part (11).

3. The piston according to Claim 2, characterised in that via the respective recess (30) the lubricating oil can be fed to the respective groove (28, 29) of the cooling oil guide sleeve (19) and / or of the piston lower part (11).

4. The piston according to any one of the Claims 1 to 3, characterised in that into the guide surface (22) of the cooling oil guide sleeve (19) and / or into the support surface (23) of the piston lower part (11) at least one oil pocket (31), preferentially at least two oil pockets (31), delimited in the circumferential direction, is introduced.

5. The piston of an internal combustion engine, with a piston upper part (10), with a piston lower part (11) connected to the piston upper part (10), with a piston pin (12), which is mounted in the piston lower part (11) and serves for connecting the piston to a connecting rod (13) of the internal combustion engine, with a first cooling space (15) formed between the piston upper part (10) and the piston lower part (11) for cooling oil for cooling the piston, wherein the first cooling space (15) is connected via at least one overflow bore (17) to a second cooling space (16) formed between the piston upper part (10) and a piston lower part (11), with a cooling oil guide sleeve (19), which serves for guiding cooling oil conducted through a bore (18) in the connecting rod (13) in the direction of the first cooling space (15), wherein a guide surface (22) of the cooling oil guide sleeve (19) adjoins a support surface (23) of the piston lower part (11), characterised in that into the guide surface (22) of the cooling oil guide sleeve (19) and / or into the support surface (23) of the piston lower part (11) at least one oil pocket (31) delimited in the circumferential direction is introduced.

6. The piston according to Claim 5, characterised in that into the cooling oil guide sleeve (19) at least one recess (30), preferentially at least two recesses (30), which extends in the radial direction and penetrates the cooling oil guide sleeve (18) is introduced via which lubricating oil can be fed to a region between the cooling oil guide sleeve (19) and the piston lower part (11).

7. The piston according to Claim 6, characterised in that via the respective recess (30) the lubricating oil can be fed to the respective oil pocket (31) of the cooling oil guide sleeve (19) and / or of the piston lower part (11).

8. The piston according to any one of the Claims 5 to 7, characterised in that the cooling oil guide sleeve (19) is formed as slit sleeve with a slit (21) extending in the axial direction, which with the guide surface (22) spring-elastically presses against the support surface (23) of the piston lower part (11).