EP3250804A1

EP3250804A1 - Piston for an internal combustion engine and method for producing the piston for an internal combustion engine

Info

Publication number: EP3250804A1
Application number: EP16702059.3A
Authority: EP
Inventors: Michael Seiffert; Hanno Necker; Georg HOPP
Original assignee: Federal Mogul Nuernberg GmbH
Current assignee: Federal Mogul Nuernberg GmbH
Priority date: 2015-01-30
Filing date: 2016-01-26
Publication date: 2017-12-06
Also published as: US20180202388A1; WO2016120246A1; US10436146B2; DE102015201633A1

Abstract

A steel piston (10) for an internal combustion engine comprises a ring zone (12), a shaft (14), openings (16) between the ring zone (12) and shaft (14) which extend from the piston outer side to the piston inner side, and, between two openings (16), a rib (18) which is substantially central with respect to a length of a piston pin to be received, wherein, when viewed in the circumferential direction, the rib (16) has a decreasing thickness from the middle thereof, as measured in the radial direction. In a method for producing a steel piston for an internal combustion engine comprising a ring zone and a shaft, openings are formed between the ring groove region and the shaft which extend from the piston outer side to the piston inner side, and at least one rib is formed between the openings which is substantially central with respect to a length of a piston pin to be received, wherein, when viewed in the circumferential direction, the rib (16) has a decreasing thickness from the middle thereof, as measured in the radial direction.

Description

Piston for an internal combustion engine and method for producing the piston for an internal combustion engine

TECHNICAL AREA

The invention relates to a piston for a

Internal combustion engine and a method for producing a piston for an internal combustion engine.

On pistons for internal combustion engines are typically

Requirements that lead to conflicting goals. Firstly, the mass of the piston should be relatively low, and on the other hand, the stiffness and

Strength of the piston occurring during operation

Requirements met.

STATE OF THE ART

For example, from US 2001/0029840 AI a steel piston is known, which is a breakthrough between a ring field and a shaft on.

JP 2010-038048 A relates to a piston having a ring field and a shaft, which has a significantly lower height, along the piston axis, than the ring field, and in one embodiment with two, substantially parallel to the piston axis extending reinforcements to the ring field supported.

10 2004 013 905 AI relates to a piston for a

Internal combustion engine, on whose inner wall at least one extending parallel to the piston center axis reinforcing rib is provided, on both sides of an opening

can be provided. PRESENTATION OF THE INVENTION

Against this background, the invention has for its object to a piston for an internal combustion engine

in which the requirements with regard to the

Weight savings on the one hand and the strength on the other hand are as equally satisfied.

The solution to this problem is achieved by the piston described in claim 1. Accordingly, this has a ring field, a shaft, openings between the ring field and shaft, ranging from the piston outside to the piston interior, and at least one with respect to a length of a male piston substantially central rib between two

Breakthroughs on. Under Ringfeld is derj enige, to the

Piston bottom adjacent region understood in which there are one or more Kolbenringnuten. The stem substantially represents the region of the piston where the piston bears against the walls of a cylinder or a piston

Cylinder liner is in sliding contact. Usually, the sheep is formed by two separate shaft walls which are located on either side of the piston pin bosses. The connection of the shaft walls to the

Piston pin hubs are made by so-called connection.

According to the invention, the described breakthroughs advantageously save weight. At the same time, the necessary strength is provided by the central rib

produced . The rib or strut thus reaches in

advantageously a stiffening of the central

Shank area and counteracts a bending down of the ring field entgege. This verse eifung causes a reduction of the elastic Schafteinfalls, whereby a substantially homogeneous contact pattern in the region of the piston shaft are generated, and tilting of the piston can be reduced during operation.

As a result, further stops a striking of the piston head on the cylinder wall, so that in addition noises are avoided in an advantageous manner. It should be added that preferably on each side of the piston pin exactly two

Breakthroughs and a single rib are provided.

The strength has proved to be favorable, and the design of the rib can in this way be arranged simultaneously with the aim of weight saving, that it has, starting from its, in the circumferential direction, center a decreasing, measured in the radial direction of the piston thickness ,

Preferred developments of the piston according to the invention are described in the further claims.

For weight savings, it offers advantages, and it has also been found that the necessary strength

can be achieved if at least one breakthrough in

Umf ngsrichtung has more than twice the width of the rib.

For the guidance of the piston and the strength in the region of the shaft, it is preferred that the shaft, in particular the individual shaft walls, have along the piston axis at least 1.5 times the height of the ring field.

For a design that works well at maximum load

is as little as possible Rissanf mature, it is preferably provided that the rib and / or the area next to at least one breakthrough in a section that contains the piston axis, concave rounded on the outside. Since the breakthrough results, for example, in the formation of a groove, such a groove formed from the outside of the piston, thus preferably has a rounded bottom.

In terms of strength is further preferred that the rib in the direction of the piston crown less far extends as along the shaft. As a result, in particular a stable configuration of the shaft walls can be achieved.

The weight saving is further achieved in that preferably a securing groove is provided for a locking ring for a piston pin, which is interrupted along its circumference at least at one point. Starting from a usual, fully circumferential locking groove, the

Breaking the same can be achieved such that the material surrounding the securing groove is partially withdrawn along the piston pin axis and in the direction of the interior of the piston, that the securing groove in these areas "disappears", and the locking ring

for example, is received only in an upper, directed to the piston crown area and in a lower region in a groove. This recording provides a sufficient angle of wrap for the retaining ring while allowing another described in the manner described

Weight savings. Preferably, the securing groove in the upper region in its circumferential direction wider,

for example, over 120 to 150 degrees and at the bottom narrower, for example, over 60 to 100 degrees, be executed. The interruptions of the locking groove also offer the advantage that no special lifting groove is required for the removal of the retaining ring, because a

Lifting tool can be set in the area of the interruption. This reduces the production costs.

Finally, it is preferred for the shank, viewed from the underside of the piston, to have a convex curvature on the outside, starting from the shank walls, and a concave curvature at the transition to the piston pin bosses. This results in a total piston shape, which is known as "Figure of Eight" and which allows a wide shaft wall as well as a sufficient safety distance of a cooling oil nozzle in the piston interior and a piston pin with a minimum length a homogeneous contact pattern on the shaft are made possible. The

Shaft connection to the connecting walls can at the same time be provided with increased flexibility, and an undesirable "rail support" can be reduced, resulting overall in a modern piston architecture.

As part of the process of the invention are in the production of a steel piston for an internal combustion engine between the ring field and shaft openings and at least one, with respect to a length of a male

Piston pin central rib formed. As a result, the corresponding advantages as in the foregoing

be achieved described piston. Further, all of the foregoing and following are given for the piston

Driving features in the invention Ve applicable and vice versa.

Preferably, at least one aperture is formed by forming a groove from the outside of the piston. This breakthrough can already be provided in the forged or cast piston, but it can edoch alternatively or additionally from the outside by forming the groove

be formed, wherein at the same time the material thickness is chosen sufficiently thick in the region of the intended rib.

Preferably, the rib is provided in the primary molding, for example, in casting or forging, or the piston is machined from its inside by milling in a suitable manner to form the rib. Finally, the training of the rib in the context of rapid prototyping is possible.

DESCRIPTION OF THE DRAWINGS

Hereinafter, a shown in the drawings

Embodiment of the invention explained in more detail. Show it: Fig. 1 is a perspective bottom view of a piston according to the invention; and

Fig. 2 is a side perspective view of a portion of the piston according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

As can be seen in FIG. 1, the piston 10 shown in a bottom view in FIG. 1 comprises a ring field 12 and a shank 14 formed by two opposing shank walls connected by connecting walls in which the piston pin bosses are provided , As can also be seen in Fig. 1, the connecting walls, starting from the j eweiligen shaft wall, first, viewed from the outside, convex, and concavely curved at the transition to the piston pin bosses.

According to the invention, along the extension of the piston pin (not shown), that is approximately at the level of the middle between the piston pin hubs 24 to be recognized, there is a central rib 18 which can be seen on the right side of the piston. In the embodiment shown, there is an opening on the right and left of the rib 18, of which only the left one according to FIG. 1 is clearly visible. The breakthrough extends from the outside of the piston to its interior and can be formed, for example, by forming a groove from the outside, and the material thickness in the areas adjacent to the rib 18 is sufficiently thin so that the openings 16 described arise. The top and / or bottom of the to

Breakthrough leading groove can, as e in addition to FIG. 2 to be largely perpendicular to the piston axis, and the bottom of the groove described, that is, the outside of the rib 18 and / or the areas 26 adjacent to the apertures 16th may be concavely curved when viewed from the outside. This is supplementary in Fig. 2 recognizable.

From Fig. 1 that the rib has a greater (radial) thickness in its center viewed in the circumferential direction than at its openings 16

directed pages. Furthermore, it extends in the

shown embodiment less wei on the underside of the piston crown than along the j eweiligen shaft wall. In Fig. 1 is also the special embodiment of a

Sicherungsnut 22 for a locking ring for a

Recognize piston pin. In particular, on the sides of the piston pin, the material of the piston on the outside is taken back so far that here the securing groove 22 "disappears", and the retaining ring is held only by the remaining in the region of the top and bottom groove portions considered, and described material recesses advantageously reduce the weight

Lifting tool be recognized, so that in vorteilhaf he way no own Aushebenut is required. Finally, in FIG. 1 also recognizes that the apertures, when in a direction perpendicular to the piston and the

Piston pin axis are considered to have rounded sides.

This is supplementary from Fig. 2 forth. In Fig. 2 it can also be seen that the respective skirt wall has a width which is substantially constant along the piston axis and, moreover, preferably also along the piston axis

Piston axis provided with constant width

Can have coating.

Claims

claims

Steel piston (10) for an internal combustion engine with a ring field (12), a shaft (14), openings (16) between Ring eld {12) and shaft (14), which extend from the piston outside to the piston interior, and one with respect to a length of to be received piston pin substantially central rib (18) between two

Breakthroughs (16),

the rib (16) starting from its, in

Seen in the circumferential direction, center a decreasing, in

Radial direction measured thickness has.

Piston according to claim 1,

characterized in that

has at least one opening (16) in the circumferential direction more than twice the width of the rib (18).

Piston according to claim 1 or 2,

characterized in that

the shaft (14) along the piston axis at least 1, 5 times the height of the ring field (12).

Piston according to one of the preceding claims,

characterized in that

the rib (18) and / or the area next to at least one opening (16) in a section that the

Piston axis contains concave rounded on the outside.

Piston according to at least one of the preceding claims, characterized in that

the rib (16) extends less far in the direction of the piston crown (20) than along the shaft (14). Piston according to at least one of the preceding claims, further comprising at least one securing groove (22) for a locking ring for a piston pin, which is interrupted along its circumference at least at one point.

Piston according to at least one of the preceding claims, characterized in that

the shaft (14) on the outside of the

Seen from the bottom of the piston, starting from the

Shaft walls a convex curvature, and at the transition to piston pin eyes has a concave curvature.

A method for producing a steel piston for an internal combustion engine having a ring field and a shaft, in which openings are formed between the ring field and the shaft, which extend from the piston outside to the piston interior, and at least one with respect to a length of a male piston pin in

Essentially central rib is formed between the breakthroughs,

the rib (16) starting from its, in

Seen in the circumferential direction, center a decreasing, in

Radial direction measured thickness has.

Method for producing a piston for a

Internal combustion engine according to claim 8,

characterized in that

at least one aperture is formed by forming a groove from the outside of the piston.

Method for producing a piston for a

Internal combustion engine according to claim 8 or 9,

characterized in that

at least one rib by archetypes, such. B. Forging or casting, milling or rapid prototyping is formed.