PISTON FOR A RECIPROCATING-PISTON INTERNAL COMBUSTION ENGINE, AND RECIPROCATING-PISTON INTERNAL COMBUSTION ENGINE

Abstract

A piston for a reciprocating-piston internal combustion engine, having a ring carrier with an outer piston crown and an inner piston crown, and comprising a piston skirt extending from the inner piston crown in the axial direction, the piston skirt having at least one at least partially arcuately formed guide surfaces, the at least one guide surface being disposed in the arcuately formed area at a distance from the ring carrier, which is adjacent in the axial direction, in such a way that a gap results between the ring carrier and the guide surface, the piston skirt and the ring carrier being connected to each other via at least one reinforcing rib, which extends transversely over the inner piston crown.

Claims

1. A piston for a reciprocating-piston internal combustion engine, the piston comprising: a ring carrier with an outer piston crown and an inner piston crown; and a piston skirt extending from the inner piston crown in an axial direction, the piston skirt having at least one at least partially arcuately shaped guide surface, wherein the at least one guide surface is disposed in the arcuately shaped area at a distance from the ring carrier, which is adjacent in the axial direction, such that a gap is formed between the ring carrier and the guide surface, and wherein the piston skirt and the ring carrier are connected to each other via at least one reinforcing rib that extends transversely over the inner piston crown.

2. The piston according to claim 1, wherein the at least one reinforcing rib extends from the inner piston crown in the axial direction in a middle section to the extent that a piston pin boss is formed in the reinforcing rib.

3. The piston according to claim 1, characterized in that the piston skirt is connected to the ring carrier via the at least one reinforcing rib and via one or multiple connecting sections between two guide surfaces.

4. The piston according to claim 1, wherein a frame-shaped structure is formed from two arcuate guide surfaces and two connecting sections extending between the guide surfaces, and wherein two reinforcing ribs are formed on an inside of the connecting sections.

5. The piston according to claim 1, wherein the ring carrier has an indentation on the surface facing the piston skirt, and wherein the at least one reinforcing rib extends transversely through the indentation such that it is connected on an outside to an inner surface of the indentation in each case.

6. The piston according to claim 1, wherein the at least one reinforcing rib and/or the at least one connecting section is/are provided with an at least partially curved design, viewed in a longitudinal direction.

7. The piston according to claim 1, wherein two piston pin bosses are provided, and the two piston pin bosses extend through a reinforcing rib corresponding to this piston pin boss.

8. The piston according to claim 1, wherein a bulge extending in the guide-through direction of a piston pin is formed on an outside of a piston pin boss and extends over the full circumference of the piston pin boss.

9. The piston according to claim 1, wherein the at least one guide surface has at least one recess, which reduces the guide surface to two or more partial guide surfaces.

10. A reciprocating-piston internal combustion engine comprising a piston according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0033] FIG. 1 shows an exemplary embodiment of a piston according to the invention in a perspective view;

[0034] FIG. 2 shows the piston from FIG. 1 in a side view according to arrow II from FIG. 1;

[0035] FIG. 3 shows the piston from FIGS. 1 and 2 in a longitudinal section according to section line III-III from FIG. 1;

[0036] FIG. 4 shows the piston from FIGS. 1 through 3 in a view from below according to arrow IV from FIG. 1;

[0037] FIG. 5 shows an exemplary embodiment of a piston according to the invention in a perspective view at an angle from below;

[0038] FIG. 6 shows the piston from FIG. 5 in a side view similar to arrow II from FIG. 1;

[0039] FIG. 7 shows the piston from FIGS. 5 and 6 in a longitudinal section according to section line III-III from FIG. 1; and

[0040] FIG. 8 shows a reciprocating-piston internal combustion engine comprising a piston according to the invention disposed therein in a schematic illustration.

DETAILED DESCRIPTION

[0041] A piston 10 according to the invention is first described in connection with FIGS. 1 through 4. In the exemplary embodiment, illustrated piston 10 is manufactured as a single piece from aluminum. Alternatively, however, it may also be manufactured in multiple parts. Independently thereof, it may alternatively or additionally also be manufactured from other materials, e.g. from steel materials.

[0042] Piston 10 comprises a ring carrier 12, which in this specific embodiment includes a total of four indentations in the form of grooves 14, which extend over the outer circumference of ring carrier 12. Three of these grooves 14the first (topmost), the third and the fourth (bottommost)are so-called annular grooves, which are used to arrange piston rings (not illustrated) and/or other sealing elements (cf. FIG. 2). Second illustrated groove 14, which has a smaller radial depth than the other grooves, is an optional relieving groove. Ring carrier 12 has an outer piston crown 16, which is oriented toward and delimits a combustion chamber in the installed state of piston 10 in a reciprocating-piston internal combustion engine. An inner piston crown 18 is formed on the side opposite outer piston crown 16, which faces away from the combustion chamber in the installed state of piston 10 in a reciprocating-piston internal combustion engine.

[0043] As is clearly apparent in FIGS. 1 through 3, a piston skirt 20 extends from inner piston crown 18 in the axial direction of piston 10. Piston skirt 20 includes two guide surfaces 22 situated opposite each other and each extending over an arc section, viewed in the circumferential direction of piston 10. Guide surfaces 22 in the present case each extend over one arc section of approximately 60. As is clearly apparent in FIGS. 2 and 3, guide surfaces 22 do not touch inner piston crown 18, because guide surfaces 22 are designed in such a way that a continuous gap 24 is formed between guide surfaces 22 and inner piston crown 18. Height H.sub.s of gap 24 in the present case is approximately 1 mm to 2 mm, viewed in axial direction A (cf. FIG. 3).

[0044] Guide surfaces 22 situated opposite each other are connected by two connecting sections 26, which each extend between guide surfaces 22. Connecting sections 26 extend between the outer ends of guide surfaces 22 in each case, viewed in the circumferential direction. Connecting sections 26 extend essentially in parallel to each other and at a distance from center point M of inner piston crown 18. As is clearly apparent in FIG. 4, connecting sections 26 are arcuately formed and are curved toward the outside. As is also clearly apparent in FIG. 4, the two guide surfaces 22 and connecting sections 26 extending between guide surfaces 22 form a frame-shaped structure.

[0045] Piston pin bosses 28, which have a circular cross section and are used to insert a piston pin (not illustrated), are formed in connecting sections 26. An outer bulge 30a and an inner bulge 30b are formed on the outside and inside of piston pin bosses 28 in each case, starting from connecting sections 26. Bulges 30a, 30b extends from a middle section of inner piston crown 18 over the full circumference of circular piston pin boss 28.

[0046] Connecting sections 26 are connected to inner piston crown 18 only in a middle area, which extends in each case over piston pin bosses 28 and bulges 30a, 30b.

[0047] Two reinforcing ribs 32 are also formed on piston 10, whichas is clearly apparent in FIG. 4extend transversely over inner piston crown 18. A reinforcing rib 32 of this type is clearly apparent in the sectional representation in FIG. 3. It is also clearly apparent that reinforcing rib 32 is connected to inner piston crown 18 over its entire extension in its longitudinal direction. In the illustrated exemplary embodiment, the height of reinforcing rib 32 extending in axial direction A approximately corresponds to depth T of the indentation in the section adjacent to an outer edge 36 of inner piston crown 18, so that reinforcing rib 32 transitions into outer edge 36 on the outside.

[0048] As is apparent in FIG. 4, reinforcing ribs 32 have an omega-shaped progression in the extension direction, and they are curved to the outside in a middle area in each case. The two reinforcing ribs 32 are formed mirror-symmetrically with respect to each other in relation to a mirror axis running through center point M. Reinforcing ribs 32 have a greater thickness in the outer areas adjacent to outer edge 36. In the exemplary embodiment, the thickness of reinforcing ribs 32 in the outer sections is approximately 9 mm with a piston diameter between 70 mm and 80 mm. The thickness of reinforcing ribs 32 in the outer areas is preferably between 5 percent and 30 percent of the piston diameter, particularly preferably between 10 percent and 20 percent.

[0049] The piston diameter of a piston 10 according to the invention is preferably between 40 mm and 200 mm, more preferably between 60 mm and 150 mm and particularly preferably between 80 mm and 120 mm.

[0050] Reinforcing ribs 32 are formed on the inside of connecting sections 26 and are oriented essentially in parallel to connecting sections 26. In a middle area, reinforcing ribs 32 and inner bulge 30b each form a unit, i.e. they are connected directly to each other so that a continuous piston pin boss 28 having a hollow cylindrical shape is formed on the inside. In the illustrated specific embodiment, these units each have a thickness D of approximately 20 percent of the piston diameter. Thickness D is preferably around 10 percent to 30 percent of the piston diameter.

[0051] In the outer areas, reinforcing ribs 32 are formed at a distance from connecting sections 26. Reinforcing ribs 32 are also situated at a distance from center point M of inner piston crown 18.

[0052] Ring carrier 12 has indentations 34 on the surface facing piston skirt 20. Indentations 34 are formed on the inside of circular outer edge 36, which extends on the outside over the entire circumference of piston 12 and has a constant thickness, Indentations 34 are separated from each other by reinforcing ribs 32 and connecting sections 26. As is apparent in FIG. 4, this results in a total of seven areas with indentations 34, taking into account the fact that indentations 34 marked by two contiguous arrows in each case also extend over the particular area which, in FIG. 4, is covered by the outer area of connecting section 26 in each case. Only one contiguous indentation 34 is therefore marked in each case by the contiguous arrows.

[0053] The shape and geometry of reinforcing ribs 32 are clearly apparent in FIG. 3 in a view perpendicular to the extension direction of reinforcing ribs 32. Reinforcing rib 32 extends on the outside from the inside of outer edge 36 within indentation 34 in the transverse direction in each case and is provided with a arcuate shape therebetween, such that piston pin boss 28 is enclosed, so that piston pin boss 28 also extends through reinforcing rib 32.

[0054] An exemplary embodiment of a piston 10 is illustrated in FIGS. 5 through 7. To describe the second specific embodiment, the same reference numerals are used for identical or at least functionally equivalent elements as in describing the first specific embodiment. Unless otherwise described or shown, piston 10 according to the second specific embodiment according to FIGS. 5 through 7 is provided with a design identical to piston 10 in the first specific embodiment according to FIGS. 1 through 4. Only the differences between the second specific embodiment and the first specific embodiment are discussed below.

[0055] Piston 10 in the second specific embodiment also has a ring carrier 12 and a piston skirt 20 extending therefrom in the axial direction, including two guide surfaces 22 extending over an arc section. One of guide surfaces 22 in the present case is divided by a recess 38 into two partial guide surfaces 40, 42, namely an upper partial guide surface 40, which is disposed closer to inner piston crown 18, and a lower partial guide surface 42, which is situated farther away from inner piston crown 18. Upper partial guide surface 40 has a greater height extending in the axial direction than lower partial guide surface 42. The height of recess 38 extending in the axial direction corresponds approximately to the height of upper partial guide surface 40 in the illustrated exemplary embodiment.

[0056] A reciprocating-piston internal combustion engine comprising a combustion chamber 44 in the form of a cylinder and a piston 10 disposed therein is illustrated schematically in FIG. 8. Piston 10 is connected to a crankshaft 48 with the aid of a connecting rod 46. Piston 10 according to the second specific embodiment described above is disposed in combustion chamber 44 in such a way that the guide surface with partial guide surfaces 40, 42 is disposed on a minor thrust face 50, and continuous guide surface 22 is disposed on a major thrust face 52. Major thrust face 52 corresponds to the side on which piston 10 rests with continuous guide surface 22 during the expansion phase after passing through the top dead center (TDC), i.e. the left side in FIG. 8, when crankshaft 48 rotates clockwise in the direction of arrow 54.

[0057] The features of the invention disclosed in the drawings and in the claims may be essential to implementing the invention in its various specific embodiments, both individually and in any combination. The invention may be varied within the scope of the claims and taking into account the knowledge of the competent person skilled in the art.

[0058] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.