Piston for an internal combustion engine, internal combustion engine with at least one such piston

Abstract

The present invention relates to a piston (1) for an internal combustion engine, comprising a piston head (2) and a piston skirt (3). The piston skirt (3) has a skirt edge (9) on an underside (8) facing away from the piston head (2) and an inner circumferential surface (11) on an inner surface (10) facing the piston's central axis (5), which defines a piston interior (12). Furthermore, the piston (1) is penetrated by a cooling oil inlet channel (13) for introducing cooling oil (7) into a cooling channel (6), which has a channel boundary surface (14), opens into the cooling channel (6) forming a first overflow opening (15), and opens into the piston interior (12) forming a second overflow opening (16).Essential to the invention is that at least one oil collection channel (17) is arranged on the inner circumferential surface (11) and the channel boundary surface (14), extending from the first overflow opening (15) of the at least one cooling oil inlet channel (13) to the skirt edge (9) of the piston skirt (3) and designed to effectively introduce a cooling oil jet (43) impinging at an offset to the cooling oil inlet channel (13) and / or inclined towards the piston's central axis into the cooling channel (6). The present invention further relates to an internal combustion engine comprising at least one such piston (1).

Description

[0001] The present invention relates to a piston for an internal combustion engine according to the preamble of claim 1. The invention relates in particular to an internal combustion engine with at least one such piston.

[0002] A piston of the type mentioned above is known from document DE 43 40 891 A1. It has a piston head and a piston skirt connected to the piston head. The piston head has a combustion bowl and a cooling channel circulating around the piston's central axis, through which cooling oil flows to cool the piston. The piston head also includes a cooling oil inlet channel, which opens into the aforementioned cooling channel at one end and terminates at the other end on an inner circumferential surface of a piston chamber in the piston skirt. Cooling oil is intended to flow into the cooling channel through the cooling oil inlet channel. However, in the case of the obliquely spraying cooling oil nozzles used in some engines, the impact area of ​​the oil jet, which is inclined at an angle to the piston's central axis, moves periodically with the piston's stroke.A disadvantage of this design is that the volume of cooling oil sprayed onto the inner surface of the piston cavity spreads across this surface, resulting in only a certain proportion of the sprayed cooling oil flow reaching the cooling channel via the cooling oil inlet. Therefore, to increase the collection efficiency, the inlet channel is designed with an elongated cross-section and a funnel-shaped collection area.

[0003] The object of the invention is therefore to provide an improved or at least a different embodiment of a piston for an internal combustion engine compared to the known prior art. Furthermore, an advantageous internal combustion engine with at least one such piston is to be specified.

[0004] In the present invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0005] To solve the first problem, a piston for an internal combustion engine is proposed, comprising a piston head and a piston skirt connected to the piston head. The piston head has a combustion bowl and is penetrated by a cooling channel running around the piston's central axis, through which cooling oil flows to cool the piston. Furthermore, the piston skirt has a skirt edge on its underside facing away from the piston head and an inner circumferential surface on its inner surface facing the piston's central axis, the said inner circumferential surface at least partially delimiting the piston's interior space. It is also provided that the piston is penetrated by at least one cooling oil inlet channel for introducing cooling oil into the cooling channel.The at least one cooling oil inlet channel has a channel boundary surface and opens into the cooling channel via a first overflow opening and into the piston interior via a second overflow opening. An improved piston can be provided according to the invention by arranging at least one continuous oil collection channel on the inner circumferential surface of the piston skirt and the channel boundary surface of the at least one cooling oil inlet channel, which extends from the first overflow opening of the at least one cooling oil inlet channel to the skirt edge of the piston skirt or which extends from the first overflow opening of the at least one cooling oil inlet channel to the skirt edge of the piston skirt.

[0006] The invention has recognized that, by means of the proposed at least one oil collection channel, cooling oil, which is sprayed, for example, as a cooling oil jet by means of a cooling oil supply device from the underside of the piston shaft through the piston interior onto the at least one oil collection channel and at least partially onto the inner circumferential surface of the piston shaft, can be collected relatively effectively due to the relatively large extension of the at least one oil collection channel, which extends from the first overflow opening of the at least one cooling oil inlet channel to the edge of the piston shaft over a complete stroke of the piston, and then transported into the cooling channel.

[0007] Particularly when using a cooling oil supply device with an obliquely spraying oil nozzle, i.e., one that generates an oil jet inclined at an angle to the piston's central axis, an impact area of ​​the oil jet oscillates periodically during the piston's stroke, essentially along a line on the inner circumferential surface of the piston skirt. An oil collection channel, arranged essentially along the line of the oil jet's impact areas, increases the oil jet's capture efficiency, especially in those piston positions where the oil jet misses direct entry into the cooling oil inlet channel. The oil collection channel guides the impacting oil jet toward the inlet channel with a relatively gentle deflection and minimal splash loss. According to the invention, even an oil jet that is parallel to the piston's central axis but impacts the cooling oil inlet channel at an angle to the cooling oil inlet channel can be introduced into the cooling channel to a greater extent.This results in an increased flow rate of cooling oil through the cooling channel, provided the volume of cooling oil sprayed onto the inner circumferential surface by the cooling oil supply device is kept constant, thus improving the cooling performance of the piston. Alternatively, if the cooling performance of the piston is to be kept constant, the volume of cooling oil sprayed onto the inner circumferential surface by the cooling oil supply device can be reduced. Due to the increased capture efficiency of the oil jet, the cooling oil flow rate, and consequently the achievable cooling performance, remains practically constant.

[0008] It is clear to the expert that the channel boundary surface of at least one cooling oil inlet channel limits the at least one cooling oil inlet channel.

[0009] It may further be provided that at least one additional continuous oil collection channel is arranged on the inner circumferential surface of the piston skirt and the channel boundary surface of the at least one cooling oil inlet channel. This additional continuous oil collection channel may also extend from the first overflow opening of the at least one cooling oil inlet channel to the skirt edge of the piston skirt and terminate at the skirt edge or even before it. Advantageously, this additional continuous oil collection channel is arranged opposite the existing additional continuous oil collection channel, particularly along a circumferential direction around the piston's central axis. This additional continuous oil collection channel is also designed to collect a cooling oil jet impinging on it and redirect it into the cooling oil inlet channel.Furthermore, it can collect cooling oil that splashes out from at least one oil collection channel and direct it into the cooling channel.

[0010] It can be advantageous if the at least one oil collection channel is integrated as a groove-like recess into the inner circumferential surface of the piston skirt and / or into the channel boundary surface of the at least one cooling oil inlet channel. In other words, the at least one oil collection channel is integrally formed with the piston. This can be achieved, for example, by forming the piston and the at least one oil collection channel together, such as by casting. Alternatively or additionally, the at least one oil collection channel could be machined into the piston by machining the piston or the piston crown and / or the piston skirt. This allows the proposed at least one oil collection channel to be provided cost-effectively.Furthermore, because at least one oil collection channel is designed as a groove-like depression, it is clear that said at least one oil collection channel is open to the piston interior, so that cooling oil sprayed onto the inner circumferential surface of the piston shaft can be effectively collected by the at least one oil collection channel.

[0011] Furthermore, the invention may provide that the at least one oil collection channel has a channel base that is recessed relative to the inner circumferential surface of the piston skirt and / or the channel boundary surface of the at least one cooling oil inlet channel, and two channel walls projecting away from the channel base and merging into the inner circumferential surface of the piston skirt and / or the channel boundary surface of the at least one cooling oil inlet channel. The channel base may be flat or concavely curved, and / or the channel walls may be concavely and / or convexly curved. The invention has demonstrated that the specified design of the at least one oil collection channel allows for the effective collection of sprayed cooling oil. This has the advantage that a comparatively large volume flow of the sprayed cooling oil can enter the cooling channel.

[0012] In particular, the piston skirt can be designed with opposing box walls featuring aligned hub bores for receiving a piston pin, and opposing skirt walls with running surfaces that incorporate at least one oil collection channel in a transition wall region of the piston skirt. This transition wall region is arranged along a circumferential direction around the piston's central axis between one of the box walls and one of the skirt walls. This arrangement advantageously positions the at least one oil collection channel within the piston. The proposed arrangement of the at least one oil collection channel can, in particular, prevent the risk of structural weakening of the piston in the area of ​​the box walls and / or the skirt walls, and / or promote cooling of the box walls and the skirt walls.

[0013] Furthermore, it may be provided that at least one oil collection channel terminates in the piston skirt. In particular, it may be provided that the piston skirt has opposing box walls with aligned hub bores for receiving a piston pin and opposing skirt walls with running surfaces. The box walls may have skirt edge sections forming the skirt edge on the underside of the piston skirt facing away from the piston head. Each skirt edge section may have a box wall end face facing away from the piston head and an inner chamfer connecting the box wall end face to the inner circumferential surface of the piston skirt, the inner chamfers each having a chamfer surface angled relative to the piston's central axis.To ensure that the cooling oil is reliably collected and directed to the cooling channel even on the underside of the piston skirt, at least one oil collection channel is designed to terminate in one of the chamfered surfaces of the inner chamfers of the cylinder wall. This allows the oil collection channel to extend into one of these inner chamfers and terminate there, enabling the collection and removal of any cooling oil that splashes onto the cylinder.

[0014] However, it is also possible that the oil collection groove extending towards the piston skirt ends or runs out before reaching the skirt. This prevents a weakening of the skirt wall in the area of ​​the skirt that could potentially promote cracking.

[0015] It may be advantageous to provide that at least one oil collection channel along the piston center axis has a concave or S-shaped profile.In particular, the at least one oil collection channel can have the following sections: a channel inlet section, in particular straight, arranged on the channel boundary surface of the cooling oil inlet channel, between which, in particular its main extent, and the piston center axis, a first angle is formed; a channel center section, in particular straight, arranged on the inner circumferential surface of the piston shaft and adjoining the channel inlet section, between which, in particular its main extent, and the piston center axis, a second angle is formed; and a channel edge section, in particular straight, arranged on the inner circumferential surface of the piston shaft and adjoining the channel center section, between which, in particular its main extent, and the piston center axis, a third angle is formed.It may be advantageous for the first angle to be larger than the second angle and / or for the third angle to be larger than the second angle. The channel's central section may be aligned parallel or slightly inclined with respect to the piston's central axis. The second angle is advantageously either 0° or lies in the range between greater than 0° and less than or equal to 10°, preferably 5°. Furthermore, the first angle may lie in the range between 10° and 45°, preferably 25°. The third angle may also lie in the range between 10° and 45°, preferably 25°. It may also be provided that the first and third angles are identical. This ensures that the channel inlet section and the channel edge section of the at least one oil collection channel are inclined less steeply with respect to the piston's central axis than the channel's central section with respect to the piston's central axis.Tests have shown that this specific design of at least one oil collection channel facilitates the transport of cooling oil towards the cooling channel. Furthermore, the S-shaped profile and the comparatively steep angle of the channel's central section prevent undesirable structural weakening of the piston in the area of ​​the cylinder walls and / or shaft walls. The S-shaped profile allows the oil collection channel to be shallower, particularly in the transition zone between the central and outer sections, thus weakening the cylinder wall less than would occur with a continuously straight and / or concave profile, which would actually be desirable for optimal collection efficiency. Therefore, the S-shaped profile allows for a longer overall oil collection channel with little or no weakening of the cylinder wall, and thus, in particular,to collect further coolant in the channel edge section and direct it towards the cooling oil inlet channel.

[0016] In particular, the at least one cooling oil inlet channel can be designed as a funnel-shaped inlet funnel that widens from the first overflow opening to the second overflow opening. The cross-section of the funnel-shaped inlet opening can be circular or oval. As mentioned above, the at least one oil collection channel is provided section by section along the funnel-shaped channel boundary surface, allowing cooling oil to be transported into the cooling channel particularly efficiently in this section.

[0017] It may also be advantageous for the cooling channel to be designed as a closed cooling channel, which is located entirely inside the piston head and, in particular, can be supplied with cooling oil exclusively via the aforementioned at least one cooling oil inlet channel. Alternatively, it may be designed as an open cooling channel, which is open to the piston's surroundings via a channel opening and, in particular, can be supplied with cooling oil exclusively via the aforementioned at least one cooling oil inlet channel.

[0018] It can also be provided that the cooling channel is arranged radially with respect to the piston's central axis between the combustion bowl and an outer ring section of the piston head. Furthermore, the cooling channel advantageously has at least one cooling oil outlet for draining cooling oil from the cooling channel. This at least one cooling oil outlet can, for example, be formed by the aforementioned channel opening. It is also advantageous if the cooling channel runs in an annular shape around the piston's central axis.

[0019] Furthermore, it is advantageous if at least one cooling oil inlet channel is formed on the piston head and / or the piston skirt. Depending on the piston design, it may be beneficial, for example, for reasons of the piston's mechanical stability, if at least one cooling oil inlet channel is formed on the piston head and / or the piston skirt.

[0020] The second problem mentioned at the outset is solved by an internal combustion engine, particularly for a motor vehicle, comprising at least one piston according to the preceding description and a cooling oil supply device configured to spray cooling oil as a free, obliquely oriented jet of cooling oil from the underside of the piston skirt of the at least one piston, through the piston cavity of the at least one piston, onto the at least one oil collection channel of the at least one piston. For this purpose, the cooling oil supply device may have a spray nozzle that is tilted at an angle relative to the piston's central axis. This provides an advantageous internal combustion engine with at least one advantageous piston.

[0021] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0022] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0023] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0024] Each of these shows, schematically, Fig. 1 in a perspective view a piston according to the invention in a first embodiment, Fig. 2 a top view of the piston from Fig. 1 in the direction of view of one in Fig. 1 registered arrow II, Fig. 3 a step-section view of the piston made of Fig. 2 from the side according to a in Fig. 2 Section line III-III marked with a solid line, Fig. 4 a step-section view of the piston made of Fig. 3 according to a in Fig. 3 Section line IV-IV marked with a solid line, Fig. 5 a step-section view of the piston from Fig. 4 according to a in Fig. 4 Section line VV marked with a solid line, Fig. 6 in a perspective view the piston from Fig. 1 to 5 from a low angle in the direction of view of a Fig. 1 registered arrow VI and Fig. 7 in a sectional view a piston according to the invention in a further embodiment.

[0025] The Fig. Figures 1 to 7 show two embodiments of a piston labelled overall with reference numeral 1 for an internal combustion engine (not illustrated), for example for a vehicle, in particular a motor vehicle, which has a piston head 2 and a piston skirt 3 integrally connected with the piston head 2.

[0026] The Fig. 1 to 4 serve in particular to clarify the in Fig. 5 shown complex step section view of the Kolbe 1. Accordingly, in the Fig. 1 of the pistons 1 according to a first embodiment in a perspective view and in Fig. 2 in a top view from the perspective of a Fig. 1. Arrow II is shown. Furthermore, in the Fig. 3 a step-sectional view of piston 1 from Fig. 2 from the side given, which according to a in Fig. 2, section line III-III, is drawn with a solid line. The in Fig. 4 illustrated step-sectional view of piston 1 from Fig. 3 is according to a in Fig. 3. Section line IV-IV, marked with a solid line, is cut open.

[0027] Especially with regard to the Fig. 5, which shows piston 1 in a step section view according to a in Fig. Section line VV, shown with a solid line, is indicated, as well as the further Fig. 6 and Fig. It is to be explained in section 7 that the piston head 2 has a combustion bowl 4 and is penetrated by a cooling channel 6 of the piston 1, which is arranged radially with respect to the piston center axis 5 between the combustion bowl 4 and an outer ring section 44 of the piston head 2 and which surrounds a piston center axis 5 indicated by a dashed line. Cooling oil 7 can flow through this cooling channel 6 to cool the piston 1. The cooling channel 6 of the piston 1 according to Fig. 1 is designed as a closed cooling channel 38 arranged completely inside the piston head 2, while the cooling channel 6 of the piston 1 according to the further embodiment according to Fig. 7 is designed as an open cooling channel 39, which is open to an environment 41 of the piston 1 via a circumferential channel opening 40.

[0028] In the Fig. Figures 1 to 7 further show that the piston shaft 3 has a shaft rim 9 on an underside 8 facing away from the piston head 2 and an inner circumferential surface 11 on an inner side 10 facing the piston's central axis 5, which at least partially defines a piston interior 12 of the piston 1. The piston shaft 3 also has opposing box walls 21 with aligned hub bores 22, which are provided for receiving a piston pin (not shown). Furthermore, the piston shaft 3 has opposing shaft walls 23 with externally arranged running surfaces 24.

[0029] Especially in Fig. 5 and Fig. Figure 7 further shows that the box walls 21 on the underside 8 of the piston shaft 3, facing away from the piston head 2, each have shaft edge sections 27 that at least partially form the shaft edge 9, each of which is provided with a box wall end face 28 facing away from the piston head 2 and an inner chamfer 29 connecting the respective box wall end face 28 with the inner circumferential surface 11 of the piston shaft 3. Each of the inner chamfers 29 has a flat or curved chamfer surface 30 that is angled relative to the piston center axis 5.

[0030] To ensure that cooling oil 7 can flow optimally into the cooling channel 6, it is provided here that, according to the [reference to be added] Fig. 1 to 6 illustrated embodiment of the piston head 2 and the piston shaft 3 and according to the in Fig. In the illustrated embodiment 7, only the piston skirt 3 is penetrated by at least one cooling oil inlet channel 13 of the piston 1 for introducing cooling oil 7 into the cooling channel 6. The at least one cooling oil inlet channel 13 has a channel boundary surface 14 that limits the at least one cooling oil inlet channel 13. Furthermore, the at least one cooling oil inlet channel 13 opens into the cooling channel 6 via a first overflow opening 15 and exits into the piston interior 12 via a second overflow opening 16, so that cooling oil 7 can enter the at least one cooling oil inlet channel 13 from the piston interior 12 via the second overflow opening 16 and then flow into the cooling channel 6 via the first overflow opening 15. Fig. Figures 1 to 6 show that at least one cooling oil inlet channel 13 is designed as an inlet funnel 37 that widens in a funnel shape from the first overflow opening 15 to the second overflow opening 16.

[0031] Furthermore, the cooling channel 6 advantageously has at least one cooling oil outlet channel 45 for draining cooling oil 7 from the cooling channel 6. In the variant with a closed cooling channel 38, this at least one cooling oil outlet channel 45 can, for example, be implemented as a bore 46 passing through the piston skirt 3. In the variant with the open cooling channel 39, the at least one cooling oil outlet channel 45 can, for example, be formed by the aforementioned channel opening 40. The open cooling channel 39 can optionally be closed by a metal plate mounted on the piston 1, which is not illustrated here.

[0032] An improved piston 1 can now be provided by arranging at least one continuous oil collection channel 17 of the piston 1 on the inner circumferential surface 11 of the piston shaft 3 and the channel boundary surface 14 of the at least one cooling oil inlet channel 13, which extends from the first overflow opening 15 of the at least one cooling oil inlet channel 13 to the shaft edge 9 of the piston shaft 3.The invention has recognized that, by means of the proposed at least one oil collection channel 17, cooling oil 7, which, purely by way of example, is sprayed as a cooling oil jet 43 by means of a cooling oil supply device 42 of the internal combustion engine from the underside 8 of the piston skirt 3 through the piston interior 12 of the piston 1 onto the inner circumferential surface 11 of the piston skirt 3, can be effectively collected and then transported into the cooling channel 6 due to the relatively large extension of the at least one oil collection channel 17, which extends from the first overflow opening 15 of the at least one cooling oil inlet channel 13 to the skirt edge 9 of the piston skirt 3.In particular, the oil collection channel 17 is designed to capture a cooling oil jet 43 emanating from a cooling oil supply device 42 with an obliquely spraying cooling oil nozzle, which is inclined at an angle to the piston's central axis with respect to the piston, relatively effectively, i.e. with the highest possible capture rate, in its impact area, which moves periodically back and forth as a result of the piston's stroke movement, and to introduce it into the cooling channel 6.

[0033] In the Fig. Figures 1 to 7 show that the at least one oil collection channel 17 is designed as a groove-like recess 18, which is machined into the inner circumferential surface 11 of the piston skirt 3 and into the channel boundary surface 14 of the at least one cooling oil inlet channel 13. The at least one oil collection channel 17 has a channel bottom 19 that is recessed relative to the inner circumferential surface 11 of the piston skirt 3 and the channel boundary surface 14 of the at least one cooling oil inlet channel 13, and two channel walls 20 projecting from the channel bottom 19 and merging into the inner circumferential surface 11 of the piston skirt 3 and the channel boundary surface 14 of the at least one cooling oil inlet channel 13. According to the figures shown in the Fig. In embodiments 1 to 3, the channel bottom 19 can be concavely curved and the channel walls 20 can be convexly curved, resulting in improved cooling oil transport.

[0034] The invention recognizes that the specified design of the at least one oil collection channel 17 allows for the effective collection of sprayed cooling oil 7. This has the advantage that a comparatively large volume flow of the sprayed cooling oil 7 can flow into the cooling channel 6.

[0035] Furthermore, especially in Fig. As can be seen in Figure 5, at least one oil collection channel 17 is formed sectionally on a transition wall area 25 of the piston shaft 3, which is arranged along a circumferential direction 26 around the piston's central axis 5 between one of the cylinder walls 21 and one of the shaft walls 23, or connects them together. This, in particular, avoids the risk of structural weakening of the piston 1 in the area of ​​the cylinder walls 21 and / or the shaft walls 23 and / or promotes cooling of the cylinder walls 21 and the shaft walls 23.

[0036] In Fig. 5 and Fig. Figure 7 further shows that at least one oil collection channel 17 terminates in the shaft edge 9 of the piston shaft 3, more precisely in one of the chamfered surfaces 30 of the inner chamfers 29 of the cylinder walls 21. Thus, at least one oil collection channel 17 extends into one of the aforementioned inner chamfers 29 and terminates there. This allows cooling oil 7 to also be collected in the area of ​​the underside 8 of the piston shaft 3 and transported to the cooling channel 6.

[0037] Continuing with a view to Fig.It should be noted that the at least one oil collection channel 17 is subdivided into several sections 31, 33, 35. A first section of these sections 31, 33, 35 is designated as channel inlet section 31 and is located at the channel boundary surface 14 of the cooling oil inlet channel 13. A first angle is formed between the channel inlet section 31 and the piston center axis 5. A second section of these sections 31, 33, 35 is designated as channel center section 33. It is located at the inner circumferential surface 11 of the piston skirt 5 and adjoins the channel inlet section 31. A second angle is formed between the channel center section 33 and the piston center axis 5. A third section of these sections 31, 33, 35 is designated as channel edge section 35. It is located on the inner circumferential surface 11 of the piston shaft 3 and adjoins the central groove section 33.A third angle is formed between the channel edge section 35 and the piston center axis 5. The first angle is designed to be larger than the second angle, and the third angle is larger than the second angle. This results in the channel inlet section 31 and the channel edge section 35 of the at least one oil collection channel 17 being inclined less steeply with respect to the piston center axis 5 than the channel center section 33 with respect to the piston center axis 5. It has been found that this specific design of the at least one oil collection channel 17 facilitates the transport of cooling oil 7 into the cooling channel 6. Reference symbol list 1 piston 2 Piston head 3 Piston shaft 4 combustion chambers 5 Piston center axis 6 Cooling channel 7 Cooling oil 8 Underside 9 shaft edge 10 Inside 11 Inner perimeter area 12 Piston interior 13 Cooling oil inlet channel 14 Channel boundary area 15 first overflow opening 16 second overflow opening 17 Oil collection channel 18 In-depth study 19 Gutter bottom 20 gutter walls 21 box walls 22 hub bores 23 shaft walls 24 running surfaces 25 Transition wall area 26 Circumferential direction 27 shaft edge section 28 Box wall end face 29 Inner chamfer 30 chamfer area 31 Gutter inlet section 33 Gutter center section 35 Gutter edge section 37 inlet funnels 38 closed cooling channel 39 open cooling channel 40 Channel opening 41 Surroundings 42 Cooling oil supply device 43 Cooling oil jet 44 Ring section 45 Cooling oil outlet channel 46 bore QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 43 40 891 A1

[0002]

Claims

[1] Piston (1) for an internal combustion engine, - with a piston head (2) and a piston shaft (3) connected to the piston head (2), - wherein the piston head (2) has a combustion bowl (4) and is penetrated by a cooling channel (6) rotating around a piston central axis (5), through which cooling oil (7) can flow to cool the piston (1), - wherein the piston shaft (3) has a shaft edge (9) on an underside (8) facing away from the piston head (2) and an inner circumferential surface (11) on an inner side (10) facing the piston central axis (5), which at least partially delimits a piston interior (12), - wherein the piston (1) is penetrated by at least one cooling oil inlet channel (13) for introducing cooling oil (7) into the cooling channel (6), which has a channel boundary surface (14), opens into the cooling channel (6) forming a first overflow opening (15) and opens into the piston interior (12) forming a second overflow opening (16), characterized by , that - at least one continuous oil collection channel (17) is arranged on the inner circumferential surface (11) of the piston shaft (3) and the channel boundary surface (14) of the at least one cooling oil inlet channel (13), which extends from the first overflow opening (15) of the at least one cooling oil inlet channel (13) to the shaft edge (9) of the piston shaft (3). [2] Piston (1) according to claim 1, characterized by , that - which at least one oil collection channel (17) is incorporated as a groove-like depression (18) into the inner circumferential surface (11) of the piston shaft (3) and / or into the channel boundary surface (14) of the at least one cooling oil inlet channel (13). [3] Piston (1) according to claim 1 or 2, characterized by , that - which has at least one oil collection channel (17) having a channel bottom (19) recessed relative to the inner circumferential surface (11) of the piston shaft (3) and / or the channel boundary surface (14) of the at least one cooling oil inlet channel (13) and two channel walls (20) projecting away from the channel bottom (19) and transitioning into the inner circumferential surface (11) of the piston shaft (3) and / or into the channel boundary surface (14) of the at least one cooling oil inlet channel (13), - wherein the channel bottom (19) is concavely or convexly curved, and / or - wherein the channel walls (20) are concavely or convexly curved. [4] Piston (1) according to any one of the preceding claims, characterized by , that - the piston shaft (3) has opposing box walls (21) with aligned hub bores (22) for receiving a piston pin and opposing shaft walls (23) with running surfaces (24), - which at least one oil collection channel (17) is formed section by section on a transition wall area (25) of the piston shaft (3), which is arranged along a circumferential direction (26) around the piston center axis (5) between one of the box walls (21) and one of the shaft walls (23) or connects them together. [5] Piston (1) according to any one of the preceding claims, characterized by , that - which at least one oil collection channel (17) extends into the shaft edge (9) of the piston shaft (3). [6] Piston (1) according to claim 5, characterized by , that - the piston shaft (3) has opposing box walls (21) with aligned hub bores (22) for receiving a piston pin and opposing shaft walls (23) with running surfaces (24), - the box walls (21) on the underside (8) of the piston shaft (3) facing away from the piston head (2) have shaft edge sections (27) forming the shaft edge (9), - wherein the shaft edge sections (27) each have a box wall end face (28) facing away from the piston head (2) and an inner chamfer (29) connecting the box wall end face (28) with the inner circumferential surface (11) of the piston shaft (3) with a chamfer surface (30) tilted at an angle to the piston center axis (5), - wherein at least one oil collection channel (17) terminates in one of the chamfered surfaces (30) of the inner chamfers (29) of the box walls (21). [7] Piston (1) according to any one of the preceding claims, characterized by , that - which has at least one oil collection channel (17) along the piston center axis (5) in an S-shaped shape. [8] Piston (1) according to any one of the preceding claims, characterized by , that - which has at least one oil collection channel (17) with a channel inlet section (31) arranged on the channel boundary surface (14) of the cooling oil inlet channel (13), between which a first angle is formed and the piston center axis (5), - which has at least one oil collection channel (17) having a channel center section (33) arranged on the inner circumferential surface (11) of the piston shaft (5) and adjoining the channel inlet section (31), between which a second angle is formed and the piston center axis (5), - which has at least one oil collection channel (17) having a channel edge section (35) arranged on the inner circumferential surface (11) of the piston shaft (3) and adjoining the channel center section (33), between which a third angle is formed and the piston center axis (5), - where the first angle is larger than the second angle, and / or - where the third angle is larger than the second angle. [9] Piston (1) according to any one of the preceding claims, characterized by , that - which at least one cooling oil inlet channel (13) is designed as an inlet funnel (37) that widens in a funnel shape from the first overflow opening (15) to the second overflow opening (16). [10] Piston (1) according to any one of the preceding claims, characterized by , that - the cooling channel (6) is designed as a closed cooling channel (38) which is arranged completely inside the piston head (2) and, in particular, can be supplied with cooling oil exclusively via the said at least one cooling oil inlet channel (13), or - the cooling channel (6) is designed as an open cooling channel (39) which is open to an environment (41) of the piston (1) via a channel opening (40) and, in particular, can be supplied with cooling oil (7) via the said at least one cooling oil inlet channel (13). [11] Piston (1) according to any one of the preceding claims, characterized by , that - which has at least one cooling oil inlet channel (13) on the piston head (2) and / or on the piston skirt (3). [12] internal combustion engine, in particular for a motor vehicle - at least one piston (1) according to any one of the preceding claims 1 to 11, - a cooling oil supply device (42) which is configured to spray cooling oil (7) as a free cooling oil jet (43) directed obliquely to the piston center axis (5) from the underside (8) of the piston shaft (3) of the at least one piston (1) through the piston interior (12) of the at least one piston (1) onto the at least one oil collecting channel (17) of the at least one piston (1).

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