Piston bolt

Abstract

A piston bolt may include an axial opening and at least one reinforcement rib may be arranged on an inner surface of the opening. The at least one reinforcement rib may be helical in conformation or may include a plurality of reinforcement ribs forming a honeycomb pattern.

Claims

1. A piston bolt comprising an axial opening and at least one reinforcement rib arranged on an inner surface of the opening, wherein: the at least one reinforcement rib is helical in conformation and includes at least two helical reinforcement ribs having helix angles oriented in opposing directions.

2. The piston bolt according to claim 1, wherein the at least two helical reinforcement ribs run in opposite directions.

3. The piston bolt according to claim 1, wherein the at least one reinforcement rib has one of a trapezoidal, a rectangular, a circular segment, and a sinusoidal cross section.

4. The piston bolt according to claim 1, wherein a ratio of a height of the at least one reinforcement rib to a residual wall thickness of the piston bolt is between 0.1 and 2.0.

5. The piston bolt according to claim 4, wherein a ratio of a height of the at least one reinforcement rib to a residual wall thickness of the piston bolt is between 0.3 and 0.7.

6. The piston bolt according to claim 1, wherein a ratio of a height of the at least one reinforcement rib to a width of the reinforcement rib is between 0.1 and 2.0.

7. The piston bolt according to claim 6, wherein a ratio of a height of the at least one reinforcement rib to a width of the reinforcement rib is between 0.1 and 0.3.

8. The piston bolt according to claim 1, wherein one of: the opening is formed as a continuous opening running entirely through the piston bolt, or a middle web is present, which separates two openings from each other, each one formed as a blind hole.

9. An internal combustion engine comprising at least one piston bolt having an axial opening and at least one reinforcement rib arranged on an inner surface of the opening, wherein the at least one reinforcement rib includes a plurality of reinforcement ribs forming a honeycomb pattern.

10. The internal combustion engine according to claim 9, wherein the plurality of reinforcement ribs forming the honeycomb pattern vary in terms of at least one of height and width over a length of the opening.

11. The internal combustion engine according to claim 9, wherein the at least one reinforcement rib has one of a trapezoidal, a rectangular, a circular segment, and a sinusoidal cross section.

12. The internal combustion engine according to claim 9, wherein one of: the opening is formed as a continuous opening running entirely through the piston bolt, or a middle web is present, which separates two openings from each other, each one formed as a blind hole.

13. The internal combustion engine according to claim 9, wherein the plurality of reinforcement ribs includes annular reinforcement ribs and axial reinforcement ribs, which intersect and together form the honeycomb pattern.

14. The internal combustion engine according to claim 9, wherein the plurality of reinforcement ribs forming the honeycomb pattern vary in terms of at least one of height and width over a length of the opening.

15. A piston bolt comprising an axial opening and at least one reinforcement rib arranged on an inner surface of the opening, wherein: the at least one reinforcement rib includes a plurality of reinforcement ribs including annular reinforcement ribs and axial reinforcement ribs, which intersect and together to form a honeycomb pattern.

16. The piston bolt according to claim 15, wherein the plurality of reinforcement ribs forming the honeycomb pattern vary in terms of at least one of height and width over a length of the opening.

17. The piston bolt according to claim 15, wherein the at least one reinforcement rib has one of a trapezoidal, a rectangular, a circular segment, and a sinusoidal cross section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There are shown, each time schematically

(2) FIG. 1 is a cross-sectional illustrative representation through a piston bolt according to the invention with an axial opening and a helical reinforcement rib running through it in the same direction,

(3) FIG. 2 is a representation like FIG. 1, but with reduced thread height of the reinforcement rib,

(4) FIG. 3 is another embodiment of the helical reinforcement rib running through in the same direction,

(5) FIG. 4 illustrates exemplary possible cross section forms of reinforcement ribs,

(6) FIG. 5 is an illustrative embodiment of the piston bolt according to the invention with two helical reinforcement ribs running in opposite direction,

(7) FIG. 6 is a representation like FIG. 5, but with reduced thread height, and

(8) FIG. 7 is a second alternative embodiment of the piston bolt according to the invention with a plurality of reinforcement ribs forming a honeycomb pattern.

DETAILED DESCRIPTION

(9) According to FIGS. 1 to 7, a piston bolt 1 according to the invention which usually couples a piston, not shown, to a connecting rod in an internal combustion engine 2, comprises an axial opening 3, on whose internal surface at least one reinforcement rib 4 is disposed. Now, according to the invention, this at least one reinforcement rib 4 is helical in conformation (see FIGS. 1 to 3 and 5 and 6), or it is provided with a plurality of such reinforcement ribs 4 which form a honeycomb pattern 5 (see FIG. 7).

(10) The at least one reinforcement rib 4 can be configured as a helical reinforcement rib and it can run uniformly through the opening 3, as shown in the embodiments per FIGS. 1 to 3. Alternatively, it is also conceivable to provide two or more helical reinforcement ribs 4 running in opposite direction, as is shown in FIGS. 5 and 6.

(11) Regarding the opening 3, one can imagine it to be fashioned as a continuous opening 7 running entirely through the piston bolt 1 or that a middle web 8 is present, which separates two openings 3 from each other, each one formed as a blind hole. Such a middle web 8 is shown, for example, in FIG. 5.

(12) If one considers the honeycomb pattern 5 formed by the reinforcement ribs 4 per FIG. 7, one notices that annular reinforcement ribs 4 and axially running reinforcement ribs 4 are provided to form the honeycomb pattern 5. The reinforcement ribs 4, 4 forming the honeycomb pattern 5 can of course vary in terms of their height h and/or in terms of their width b along the length of the opening 3, which can be formed for example by honeycombs 6 of different size and/or different spacings between the individual honeycombs 6, so that the honeycomb pattern 5 can be designed for the individual loads according to the regions of the piston bolt 1.

(13) In the individual reinforcement ribs 4 according to FIGS. 1 to 3 and 5 to 7 one notices that they substantially have a rectangular cross section with partly rounded corners. Alternatively, it is also conceivable that at least one reinforcement rib 4 has a trapezoidal or a sinusoidal cross section, as is shown for example with the reinforcement ribs 4 of FIG. 4. Furthermore, the reinforcement ribs 4 can be hardened, which is possible with no problems on account of the enlarged surface of the reinforcement ribs 4 by means of a faster cooldown process.

(14) In one advantageous modification of the solution according to the invention, a ratio of the height h of at least one reinforcement rib to a residual wall thickness R of the piston bolt 1 can be defined as follows:

(15) 0.1<h/R<2.0 and preferably 0.3<h/R<0.7.

(16) Furthermore, a ratio of a height h of the at least one reinforcement rib 4 to a width b of same can be defined as follows:

(17) 0.1<h/b<1.0, preferably 0.1<h/b<0.3.

(18) In the size ratios given, an optimal compromise can always be achieved between h, R and b (height, residual wall thickness and width), so that the strength, the deformation behaviour and the weight can be influenced. One benefit of the invention specified here is therefore that the piston bolt 1 can be designed according to requirements by appropriate adaptation of the three parameters h, R, b (and material).

(19) The reinforcement ribs 4 configured according to the invention can heighten both a bending resistance and a resistance to transverse ovalization, and at the same time reduce the weight of the piston bolt 1, so that the moved mass can be reduced and at the same time the load bearing ability can be increased.

(20) The reinforcement ribs 4 can be produced, for example, by a machining of the inner surface, by a cold flow process, or a pressing with interior mould, while in particular the production of the honeycomb pattern 5 with the individual honeycombs 6 is also possible by using certain salt or sand cores. Such a honeycomb pattern can preferably also be accomplished by a metal injection moulding process (metal-matrix compound). This makes possible high precision with low tolerances (e.g., an application for internal gears). Depending on the choice of material and the composition, the hardness, thermal conductivity, and so on can thus also be adjusted.