Piston and internal combustion engine with such a piston

Abstract

Piston (1) of an internal combustion engine (2) with a cooling channel (6) rotating in a piston head (3) and open towards a piston skirt (5), which is covered by a two-part, semicircular cooling channel cover (8) which is supported on one side by a radially inner support (7) arranged in the cooling channel (6), characterized in that - that the semicircular cooling channel cover (8) with its outer edge (11) rests under preload against a ring web end face (12) of a ring web (13), - that a pin-shaped retaining contour (15) projects from the ring bridge end face (12) or from the semicircular cooling channel cover (8) in a substantially axial direction (14), - that the semicircular cooling channel cover (8) has a retaining recess (16) on its outer edge (11) or the ring web end face (12) that is complementary to the pin-shaped retaining contour (15), by means of which the semicircular cooling channel cover (8) is supported in the radial direction.

Description

[0001] The present invention relates to a piston of an internal combustion engine with a cooling channel that is ring-shaped and open towards a piston skirt in a piston head, according to the preamble of claim 1. The invention further relates to an internal combustion engine with a cylinder and a piston arranged therein.

[0002] From DE 10 2004 019 010 A1, a generic piston of an internal combustion engine is described, comprising a cooling channel that runs annularly around a piston head at the level of a piston ring band and is open towards a piston skirt, and which is supported by a two-part, semi-circular cooling channel cover that is supported on one side by a radially inner support arranged in the cooling channel, wherein the semi-circular cooling channel cover bears under axial preload with its inner edge against the radially inner support which is attached to a ring rib and designed as a circumferential shoulder.To avoid wear, the two-part cooling channel cover is designed in its supports such that, in the relaxed state, it has a circumferentially varying, location-dependent spring force acting radially outwards, whereby the semi-circular cooling channel cover rests under axial preload with a constant surface pressure on the radially inner and outer arranged supports.

[0003] From DE 10 2014 015 947 A1, an annular cooling channel cover for a piston of an internal combustion engine, made of an elastic material, is known. The cover has opposing end faces, and at least two opposing end regions form a butt gap. A connecting element for cooling oil is further provided, which is received in an opening in the cooling channel cover and held in place by a snap-fit ​​connection. In an end region adjacent to a butt gap, an opening is provided for receiving at least one supply element. The supply element has two spring tabs extending radially outward in the circumferential direction of the cooling channel cover at the inlet region and two elastic snap-fit ​​elements extending radially in the circumferential direction of the cooling channel cover at the outlet region, thus enabling simple fixation of the supply element to the cooling channel cover.

[0004] From EP 0 334 855 B1, a coolable plunger piston for internal combustion engines is known, consisting of a head part with hubs molded onto it for receiving the piston pin connecting the piston to the connecting rod, an outer ring wall extending at a first end into the base of the piston head and open at its second end for receiving at least one piston ring groove, and with a radially inner section adjoining this ring wall and open to the second end of the ring wall, the hubs or their support parts extending to the base of the piston head.

[0005] Generally, conventional pistons, including conventional so-called monotherm pistons, require a comparatively high level of machining for an external cover plate receptacle (i.e., an external support for a semi-circular cooling channel cover). This is due to the complex contour, tight tolerances of the piston's outer diameter, and the equally tight tolerances of the outer diameter of the semi-circular cooling channel cover. Furthermore, the semi-circular cooling channel cover must be negatively compressed during assembly, which increases the stress on the cover and complicates the process. The particularly tight tolerances of a shoulder on a ring land face necessitate a comparatively high level of machining, making such pistons expensive.

[0006] The present invention therefore addresses the problem of providing an improved or at least an alternative embodiment for a piston of the generic type, which in particular enables more cost-effective manufacturing.

[0007] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0008] The present invention is based on the general idea of ​​providing a pin-shaped retaining contour, projecting substantially in the axial direction, on a semicircular cooling channel cover or on an annular web end face, which interacts with a retaining recess arranged on the annular web end face or the semicircular cooling channel cover and designed complementarily thereto, so that both an anti-rotation feature and a radial locking feature of the semicircular cooling channel cover can be created via this pin-shaped retaining contour and the retaining recess, thereby eliminating the need for the previously required and comparatively tight tolerance shoulder on the annular web end face and thus making the piston easier and more cost-effective to manufacture overall.The piston according to the invention for an internal combustion engine has a cooling channel that runs annularly around a piston crown at the level of a piston ring band and is open towards a piston skirt. This cooling channel is covered by a two-part, semicircular cooling channel cover, which is supported on one side by a radially inner support arranged in the cooling channel. This cooling channel cover rests under axial preload with its inner edge against the radially inner support, which is attached to an annular rib and designed as a circumferential shoulder. By inserting the semicircular cooling channel cover into the radially inner support designed as a circumferential shoulder, the semicircular cooling channel cover is fixed to the radially inner support, and its outer edge is axially preloaded against an annular web end face of an annular web.According to the invention, a pin-shaped retaining contour projects in a substantially axial direction from the annular web end face of the piston or from the semicircular cooling channel cover. Furthermore, either the semicircular cooling channel cover has a retaining recess at its outer edge, or the annular web end face has a recess designed to be complementary to the pin-shaped retaining contour, by which the semicircular cooling channel cover is supported in the radial direction. Thus, if the pin-shaped retaining contour is located at the annular web end face, the semicircular cooling channel cover has a retaining recess at its outer edge designed to be complementary to it and is supported by this recess against the pin-shaped retaining contour on the piston side.If, on the other hand, the pin-shaped retaining contour is arranged on the semicircular cooling channel cover, an axially extending bore can, for example, be arranged in the ring web end face, into which the pin-shaped retaining contour on the cooling channel cover side engages and is supported radially by it. However, the arrangement of the pin-shaped retaining contour on the piston-side ring web end face is usually preferred. Regardless of whether the pin-shaped retaining contour is arranged on the ring web end face or on the semicircular cooling channel cover, the design according to the invention allows for the creation of a flat ring web end face that can be produced without a separate step, thereby significantly loosening the previously required tight tolerances.The outer diameter of the semi-circular cooling channel cover can also have higher manufacturing tolerances, which also simplifies the manufacturing of the cooling channel cover.

[0009] A further advantage lies in the positional accuracy of the cooling channel cover, or of an inlet and outlet opening within it, as this is subject to fewer tolerances and can therefore be manufactured more precisely. Previously, this accuracy depended on the outer diameter of the piston and the cooling channel cover, as well as on the diameter and radial position of the cooling channel cover on the piston, and on form tolerances of the cooling channel cover. With the piston according to the invention, the positional tolerances depend only on the inner diameter and the radial thickness of the semicircular cooling channel cover in the area of ​​the recess for the pin-shaped retaining contour. By eliminating the outer shoulder on the ring web end face, which was previously required for the radial fixation of the cooling channel cover, the machining ratio of cooling channel depth to plunge height can also be favorably influenced.Alternatively, it is also conceivable to place a radially inner support further downwards, resulting in higher strength in this area and less curvature under a combustion chamber recess of the piston.

[0010] Another major advantage of the piston according to the invention is that only a single pin-shaped retaining contour is required for the radial fixation of the semi-circular cooling channel cover, instead of a semi-circular circumferential shoulder, which was significantly heavier, as was previously the case. This allows the piston to be built lighter overall, which benefits the performance of an internal combustion engine equipped with such a piston.

[0011] In an advantageous embodiment of the piston according to the invention, the pin-shaped retaining contour is formed integrally with the annular web or the semicircular cooling channel cover. An integral design with the annular web, i.e., with the piston, offers the significant advantage that separate and subsequent assembly of the pin-shaped retaining contour to the piston is unnecessary. Similarly, with an integral design of the pin-shaped retaining contour on the semicircular cooling channel cover, the pin-shaped retaining contour can be manufactured simultaneously with the semicircular cooling channel cover, thus eliminating the need for subsequent assembly. This allows for a more cost-effective overall manufacturing process for the piston.

[0012] In a particularly preferred embodiment of the piston according to the invention, a bore / opening is provided in the annular web end face or in the semicircular cooling channel cover, into which the pin-shaped retaining contour is inserted. In this case, the pin-shaped retaining contour can, for example, be designed as a pin or as a snap-fit ​​sleeve and pressed into the bore in the annular web end face, thereby achieving a reliable and extremely secure fixation of the pin-shaped retaining contour in the piston. The snap-fit ​​sleeve design, in particular, offers the significant advantage that such a snap-fit ​​sleeve is first reduced in its outer diameter by compression before being inserted into the corresponding bore, so that it can then be easily inserted into the bore with the reduced outer diameter. Upon release of the compression, the snap-fit ​​sleeve expands and is thereby firmly and reliably fixed in the bore.

[0013] The term "drilling" can of course also be understood as an opening of a different design throughout the entire application.

[0014] The pin-shaped retaining element is advantageously pressed, soldered, welded, or glued into the bore. Regardless of the design of the pin-shaped retaining element, for example, as a solid pin or a snap-fit ​​sleeve, a press fit or a material-fit or force-fit connection between the pin-shaped retaining element and the bore can be used for additional security. Press-fitting, in particular, allows for energy-saving and rapid fixing of the pin-shaped retaining element in the corresponding bore.

[0015] In an advantageous embodiment of the piston according to the invention, the semi-circular cooling channel cover is designed as a spring steel sheet. The main advantages of spring steel sheets are high elasticity, high strength, durability, and corrosion resistance. Furthermore, temporary disassembly, particularly for maintenance purposes, is easily possible without damaging the semi-circular cooling channel cover.

[0016] In a particularly preferred embodiment of the piston according to the invention, the semicircular cooling channel cover has an inlet or outlet opening. Such an inlet or outlet opening serves to introduce cooling oil into the cooling channel or to discharge cooling oil from it. Naturally, a feed funnel can also be provided in the area of ​​the inlet opening, through which cooling oil is supplied to the cooling channel and which serves to better capture a jet of cooling oil.

[0017] In a further particularly preferred embodiment of the piston according to the invention, the inlet openings and the outlet opening are diametrically opposed when the cooling channel cover is mounted on the piston. This offers the significant advantage that the semicircular cooling channel covers can, for example, be designed as identical parts, so that each can be used for either an inlet opening or an outlet opening. This reduces the number of parts required and, consequently, also the storage and logistics costs.

[0018] The piston is designed as a monotherm piston. Monotherm pistons are one-piece forged steel pistons that have an integrated heat exchanger and do not require a separate piston skirt. These monotherm pistons allow for easy installation and offer improved durability and performance compared to other designs, as the piston is made entirely of steel and requires no joints between the piston crown and skirt.

[0019] The present invention is further based on the general concept of an internal combustion engine with a cylinder and a piston arranged therein, as described in one of the preceding paragraphs. This allows the advantages described with respect to the piston according to the invention to be transferred to the internal combustion engine according to the invention. Specifically, these advantages lie in a reduced weight of the piston, since, in contrast to a previously required circumferential shoulder on an annular land face for the radial fixation of a cooling channel cover, only a pin-shaped retaining contour, which is significantly lighter, is now required. Furthermore, the manufacturing effort in the area of ​​the annular land face or the shoulder previously required there can also be significantly reduced, thereby minimizing the manufacturing effort and thus also the cost of the piston.

[0020] Another major advantage lies in the increased possible tolerances both in the area of ​​the ring land face of the piston and in the area of ​​the semi-circular cooling channel cover, which also enables more cost-effective production due to the reduced manufacturing accuracy.

[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] They show, each schematically Fig. 1 a view from below of a piston according to the invention, Fig. 2 a sectional view through the piston according to the invention.

[0025] According to the Fig. 1 and Fig. 2 has a piston 1 according to the invention of an internal combustion engine 2 according to the invention (compare Fig. 2) a cooling channel 6, which is annularly circumferential in a piston head 3 at the level of a piston ring band 4 and is open towards a piston skirt 5. The cooling channel 6 is covered by a two-part, semicircular cooling channel cover 8, which is supported on one side by a radial inner support 7 arranged in the cooling channel 6, wherein the cooling channel cover 8 is under axial preload with its inner edge 9 (compare Fig. 2) rests on the radially inner support 7, which is attached to a ring rib 10 and designed as a circumferential shoulder.

[0026] At an outer edge 11, the semicircular cooling channel cover 8 rests under preload against an annular web end face 12 of an annular web 13. In the area of ​​the annular web 13, there are also annular grooves, not further specified, for receiving, for example, piston rings. In the present case, a pin-shaped retaining contour 15 projects from the annular web end face 12 of the annular web 13 in a substantially axial direction 14, while the semicircular cooling channel cover 8 has a retaining recess 16 at its outer edge 11, which is complementary to this pin-shaped retaining contour 15 and by means of which the semicircular cooling channel cover 8 is supported in the radial direction.

[0027] The axial direction 14 refers to an axis of the piston 1, while the radial direction is orthogonal to the axial direction 14.

[0028] Alternatively to the ones in the Fig. 1 and Fig. In the embodiments shown in Figure 2, it is also conceivable that a pin-shaped retaining contour 15 projects from the semicircular cooling channel cover 8 in a substantially axial direction 14, while in this case a retaining recess 16, for example in the form of a bore, is provided on the ring web end face 12, which is complementary to the pin-shaped retaining contour 15, and by means of which the semicircular cooling channel cover 8 is then supported in the radial direction.

[0029] The in the Fig. 1 and Fig. However, the embodiment shown in Figure 2 represents the preferred embodiment.

[0030] The pin-shaped retaining contour 15 can be formed integrally with the ring web 12 or alternatively with the cooling channel cover 8, thus eliminating the need for subsequent assembly, which in this case reduces the assembly costs and therefore also the manufacturing costs of the piston 1 according to the invention.

[0031] To accommodate the pin-shaped retaining contour 15, a bore 17 can be provided in the annular web end face 12 of the annular web 13 of the piston 1, into which the pin-shaped retaining contour 15 is inserted. If the pin-shaped retaining contour 15 is arranged on the semicircular cooling channel cover 8, a corresponding bore / opening (not shown) for receiving the pin-shaped retaining contour 15 is naturally provided in the latter. Generally, the pin-shaped retaining contour 15 can be designed as a solid pin or as a snap-fit ​​sleeve, with a snap-fit ​​design, for example, corresponding to the Fig. Figure 1 shows the advantage of such a pin-shaped retaining contour 15, designed as a split sleeve, in its comparatively simple assembly. For installation in the corresponding bore 17, the pin-shaped retaining contour 15 only needs to be compressed, thereby reducing its diameter, so that it can then be easily inserted into the bore 17. Once the pin-shaped retaining contour 15, designed as a clamping sleeve, has reached its final installation position, it is released, expands, and thus clamps itself firmly in the bore 17.

[0032] If the pin-shaped retaining contour 15 is designed as a solid pin, it can also be pressed into the bore 17 and fixed there using a press fit. Additional fixing measures such as soldering, welding, or gluing are also conceivable.

[0033] The bores 17, insofar as they are arranged in the ring web 13, can for example also be designed as drainage bores into which the respective pin-shaped retaining contour 15 is subsequently inserted.

[0034] The pin-shaped retaining contour 15, together with the complementary retaining recess 16, not only provides a radial stop for the semi-circular cooling channel cover 8, but also an anti-rotation device, which is of particular importance for the positioning of an inlet or outlet opening (not described or shown) in the semi-circular cooling channel cover 8.

[0035] With the cooling channel cover 8 installed, the inlet and outlet openings can be diametrically opposed, ensuring reliable flow of cooling oil through the cooling channel 6 and thus optimal cooling of the piston 1. A further major advantage of this arrangement of the inlet and outlet openings is that the semicircular cooling channel covers 8 can be manufactured as identical parts. The semicircular cooling channel cover 8 thus comprises a semicircular section with corresponding dimensions. Fig. 1 and Fig.2 shown retaining recess 16 and each an inlet opening or an outlet opening. The inlet opening and the outlet opening can also be arranged in the region of a respective end region of the semicircular cooling channel cover 8 and be designed as a semicircular recess in each cooling channel cover 8, so that the two buttressed semicircular cooling channel covers 8 together form such an inlet opening or outlet opening at their joint.

[0036] The semi-circular cooling channel cover 8 can also be designed as a spring sheet, which allows the spring preload introduced at the radially inner support 7 to be used in the long term to preload the semi-circular cooling channel cover 8 with its outer edge 11 firmly in the axial direction 14 against the ring web end face 12.

[0037] In order to ensure additional securing of the semi-circular cooling channel cover 8 on the piston 1, it is of course also conceivable that it is additionally fixed by weld points or similar material-bonded connections.

[0038] The piston 1 itself can, for example, be designed as a monotherm piston, which ensures high load-bearing capacity and a long service life. This is because it offers significantly improved heat distribution and is also easier to manufacture, as there is no separate piston skirt that first needs to be connected to the piston crown, for example by welding. All in all, such a piston 1 can therefore be used without problems in diesel engines. Reference symbol list 1 piston 2 Internal combustion engine 3 Piston head 4 piston ring band 5 Piston shaft 6 Cooling channel 7 radial inner support 8 Cooling channel cover 9 inner edge 10 Ring rib 11 outer edge 12 Ring bridge end face 13 Ring Bridge 14 Axial direction 15 pin-shaped retaining contour 16 Retaining recess 17 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 10 2004 019 010 A1

[0002] DE 10 2014 015 947 A1

[0003] EP 0 334 855 B1

[0004]

Claims

[1] Piston (1) of an internal combustion engine (2) with a cooling channel (6) rotating in a piston head (3) and open towards a piston skirt (5), which is covered by a two-part, semi-circular cooling channel cover (8) which is supported on one side by a radially inner support (7) arranged in the cooling channel (6), characterized by , - that the semicircular cooling channel cover (8) with its outer edge (11) rests under preload against a ring web end face (12) of a ring web (13), - that a pin-shaped retaining contour (15) projects from the ring bridge end face (12) or from the semicircular cooling channel cover (8) in a substantially axial direction (14), - that the semicircular cooling channel cover (8) has a retaining recess (16) on its outer edge (11) or the ring web end face (12) that is complementary to the pin-shaped retaining contour (15), by means of which the semicircular cooling channel cover (8) is supported in the radial direction. [2] Piston (1) according to claim 1, characterized by , that the pin-shaped retaining contour (15) is formed integrally with the ring web (13) or the semicircular cooling channel cover (8). [3] Piston (1) according to claim 1 or 2, characterized by , that a bore (17) is provided in the ring web end face (12) or in the semicircular cooling channel cover (8) into which the pin-shaped retaining contour (15) engages. [4] Piston (1) according to any one of claims 1 to 3, characterized by , that the pin-shaped retaining contour (15) is designed as a pin or as a detonating sleeve. [5] Piston (1) according to claims 3 and 4, characterized by, that the pin-shaped retaining contour (15) is pressed, soldered, welded or glued into the bore (17). [6] Piston (1) according to any one of the preceding claims, characterized by , that the semicircular cooling channel cover (8) is designed as a spring sheet. [7] Piston (1) according to any one of the preceding claims, characterized by , that the semicircular cooling channel cover (8) has an inlet opening or an outlet opening. [8] Piston (1) according to claim 7, characterized by , that the inlet opening and the outlet opening are diametrically opposite each other when the cooling channel cover (8) is mounted on the piston (1). [9] Piston (1) according to any one of the preceding claims, characterized by , that the piston (1) is designed as a monotherm piston. [10] Internal combustion engine (2) with a cylinder and a piston (1) arranged therein according to one of the preceding claims.

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