EP2888466A1

EP2888466A1 - Joined connection on a two-piece steel piston and joining method

Info

Publication number: EP2888466A1
Application number: EP13752639.8A
Authority: EP
Inventors: Eberhard Weiss; Emmerich Ottliczky
Original assignee: KS Kolbenschmidt GmbH
Current assignee: KS Kolbenschmidt GmbH
Priority date: 2012-08-23
Filing date: 2013-08-23
Publication date: 2015-07-01
Also published as: WO2014029878A1; DE102013216854A1; US20160061326A1; US11098800B2; US20180051805A1

Abstract

The present invention relates to a piston (1, 31), in particular a gallery-cooled piston for an internal combustion engine, having a piston bottom part (2, 32) and a piston top part (3, 33) which are connected in a joining process to produce the piston (1, 31), wherein the piston top part (3, 33) has at least one ring zone (16) and an inner wall (7), wherein it is provided according to the invention that the piston bottom part (2, 32) has a radially circumferential oblique surface (6) at the end which faces the piston top part (3, 33), which oblique surface (6), interacting with the inner wall (7) of the piston top part (3, 33), brings about a centring action (10) during the joining process of the piston parts (2, 3; 32, 33). Furthermore, the invention relates to a joining method for manufacturing a piston.

Description

DESCRIPTION

Joining connection to a two-part steel piston and joining process

The invention relates to a piston for an internal combustion engine and to a method for producing a piston for an internal combustion engine, according to the features of the respective preamble of the independent claims.

From DD 123 962 it is known that pistons for internal combustion engines consist of at least two parts. These two parts are on the one hand a Ringteii, u.a. forms the top land and at least one, preferably comprises two or more annular grooves, and a base part, which forms the Kolbenbotzenbohrung, the piston hubs, the piston skirt and the like in a conventional manner. These two parts are assembled in a suitable form. The ring element and the base part are designed so that after their assembly, a cooling channel is formed. In addition, but not necessarily, the piston may include a combustion bowl.

DE 10 2010 056 220 A1 discloses a welded connection for the production of a piston from at least two individual parts. However, the correct position mounting the piston parts is very expensive here, as a positioning missing.

In DE 10 2007 036 236 A1, a built, in particular two-part piston of an internal combustion engine having a piston upper part and a piston lower part, which are connected via a thread disclosed. However, the connection of the piston parts by a screw connection is very labor intensive and therefore costly. As joining methods are z. As caulking, soldering, welding, screwing, pinning or the like. It is essential that from the two above-mentioned two individual parts (ring element and base part) after their joining a one-piece piston is formed, this one-piece piston after completion in the usual form with rings, bolts, pin safety and the like, a ready-to-use piston is produced.

In the previously known joining methods, there is always the disadvantage that the two components to be joined together must be precisely matched to one another in order to be able to carry out the joining method.

The invention is therefore based on the object to provide a piston of an internal combustion engine, in particular a cooling channel piston, which can be made simple, but at the same time with high precision, without complex post-processing are required after joining the two components.

According to the invention it is provided that the two components (ring element and base part, also called lower part)) then center themselves when they are brought together, and form a required gap for a joint connection (in particular a cohesive joint connection, such as soldering or welding) by their processing ,

The present invention relates to a piston, in particular a cooling channel piston for an internal combustion engine, comprising a piston lower part and a piston upper part, which are connected in a joining process to form a piston, wherein the piston upper part has at least one annular field and an inner wall, wherein according to the invention it is provided that the piston lower part radially encircling inclined surface on the piston upper part facing the end, which causes a centering cooperating with the inner wall of the piston upper part in the joining process of the piston parts. In one embodiment, the piston upper part can be designed so that it includes the later ring field and the later Muldenrandbereich. This piston upper part is designed in an annular manner with an inverted U-shaped profile with different leg lengths. The outer longer leg later forms the ring field. The later bowl edge area is formed by the shorter inner leg. The advantage here is that in highly stressed areas a suitable, deviating from the piston base material can be used.

Furthermore, the invention provides that the lower piston part has at least one sliding surface, which cooperates in the joining process with the inner wall of the piston upper part. This at least one Gleitfiäche offers the advantage that low forces are spent in the joining of piston lower part and upper piston part.

Furthermore, the invention provides that at least one support for the formation of a gap is provided in the region of at least one joining seam. The at least one edition creates a gap with defined dimensions.

It is further provided that the gap adjacent to the support serves to receive soldering material.

In addition, it is provided that a depot, in particular for receiving solder material is provided. In conjunction with the support, the gap forms a reservoir for process media. It is advantageous that this reservoir can be specifically filled, for example, before the joining process. After joining, the process medium, for example, solder material in the correct dosage at the site of action exists. After performing, for example, a soldering process for connecting the piston parts, the excess soldering material, including portions of the reservoir, can be removed.

Characteristic of the piston is that on the piston upper part a circumferential collar as a limitation in the joining process in conjunction with a support is provided. Advantageously, the exact subsequent (height) - aß of the piston is defined via the collar. A "collapse" of the piston unit over the boundary, formed by the collar and the support, is only possible if a definable limit force is exceeded.The intended limitation can not be exceeded in the joining process according to the invention.

In one embodiment, it is provided that the collar is removed after completion of the joining process. Possible handling marks on the collar of the joining process are removed by removing the collar. Also, the exact dimension of the piston can be adjusted by removing the collar. The collar serves as an aid to finding the exact position of piston lower part and upper piston part in the joining process to each other and can therefore be removed after the joining.

Furthermore, the invention provides that the piston upper part forms at least one ring field after the joining process. The ring field is used in a known manner for receiving piston rings.

The inventive method for producing a piston, in particular cooling channel piston for an internal combustion engine, comprises the following steps:

Provision of the piston upper part and the piston lower part,

-Füge of the piston parts, which is provided according to the invention, that during the joining process, a centering of piston upper part to lower piston part takes place.

A centering increases the process reliability when joining the piston lower part and upper piston part to a piston. By centering, the piston components "find" themselves in the correct position relative to each other as they move towards each other Piston base and piston upper slide together to the correct end position to complete the joining process is above the midpoint in the direction of the piston stroke axis of the piston lower part. In one embodiment of the manufacturing method, it is provided that at least one support for the joining process is removed in at least one further method step. The support is used to find a defined position of the lower part of the piston to the upper part of the piston and can therefore be removed after the joining process has been completed.

For the sake of completeness, it should be mentioned that the two components to be assembled can consist of the same or different material. In addition, they may be used in the same or different ways {e.g. Forging, casting or the like).

Embodiments of the invention will be explained in more detail with reference to the accompanying figures.

Show it:

1 is a sectional view of the piston of a first embodiment prior to joining,

2 shows a sectional view of the piston after joining,

3 is a sectional view of a finished piston,

4 is a sectional view of the piston of a second embodiment,

5 is a sectional view of a piston after joining,

Fig. 6 is a sectional view of a piston before the closure of the groove and

Fig. 7: a sectional view of the finished piston.

FIGS. 1 to 3 show a first exemplary embodiment of a piston 1 according to the invention, and FIGS. 4 to 7 show a further exemplary embodiment of a piston 1 according to the invention According to the invention piston 31. For the same elements the same reference numerals are used for both embodiments.

In the following description of the figures, terms such as top, bottom, left, right, front, back, etc. refer exclusively to the example representation and position of the device and other elements selected in the respective figures. These terms are not intended to be limiting, that is to say that different positions and / or mirror-symmetrical design or the like may change these references.

1 shows a piston 1, consisting of a piston lower part 2 and a piston upper part 3, designed as a ring, before joining. The piston upper part 3 has a support 4. In addition, it may have a depot 5, which may serve for example for receiving solder paste. In addition, the lower piston part 2 has a radially peripheral oblique surface 6 on the outer circumference. With F, the joining direction for joining piston lower part 2 and upper piston part 3 is marked. When joining the lower piston part 2 and upper piston part 3, a radially encircling inner wall 7 of the piston upper part 3 slides past radially circumferential sliding surfaces 8 of the piston lower part 2. Furthermore, the annular piston upper part 3 has a radiaiumlaufenden to the piston center oriented collar 14. In the upper end region of the piston lower part 2 is a radially encircling support 15. The joining process is completed when the lower portion of the inner wall 7 comes to rest on the inclined surface 6 and the collar 14 comes to rest on the support 15. The inclined surface 6 assumes the function of a centering device during the joining process. Before the joining process can, but need not, be introduced into the depot 5 auxiliaries such as solder paste. Also, the inclusion of materials or materials that serve for subsequent cohesive connection between the piston lower part 2 and upper piston part 3, in the depot 5 is conceivable.

FIG. 2 shows the later piston 1 after the joining process of piston lower part 2 and piston upper part 3. It can be clearly seen that the inner wall 7 of the annular piston upper part 3 rests against the radially encircling inclined surface 6 of the piston lower part 2 has come to the plant. Furthermore, the radially encircling collar 14 of the upper piston part 3 has come to rest on the likewise radially encircling support 15 of the Kofbenunterteiis 2. By joining the lower piston part 2 with the piston upper part 3, a radially encircling cavity has formed, which can serve as a cooling channel 13. Furthermore, the lower piston part 2 has a trough 11, in which the combustion process takes place during operation of the internal combustion engine.

In the figure 3 the now one-piece finished piston 1 is shown. Clearly visible are joint seams 17, which mark the transition region between the former piston lower part 2 and upper piston part 3. In a region 18 of the piston was machined so that a largely planar radially circumferential surface is formed. For this purpose, the collar 14 and parts of the support 15 has been removed. Furthermore, a radially encircling annular field 16 was introduced in the upper region of the piston 1. In the area between the inclined surface 6 of the piston lower part 2 and the upper piston part 3, a cohesive connection can take place, for example by welding or soldering. A tight connection between the upper piston part 3 and lower piston part 2 is advantageous to a leakage of cooling medium from the Kühlkana! 13 to prevent.

The second embodiment of a piston 31 produced according to the invention will be described starting from FIG. A piston lower part 32 in turn has a radially encircling inclined surface 6. The annular upper piston part 33 has in profile the shape of an inverted "U" with unequal legs 19, 20. The longer, outer leg 19 is used after the joining process to form the ring field 16. The shorter leg 20 is used after the joining process for Forming a Muldenrandrings 12. The piston lower part 32 has in the region of a trough formed after the joining process 11 a radially encircling web 21. Furthermore, a sliding surface 8 and an inclined surface 6 are formed on the upper outer circumference of the piston lower part 32. When joining upper piston part 33 and lower piston part 32 in the joining direction F, an inner wall 7 of the piston upper part 33 slides along the sliding surface 8 of the piston lower part 32. The joining process ends when the lower end of the inner wall 7 of the piston upper part 33 comes into contact with the inclined surface 6 of the piston lower part 32 Standstill when the lower end of the short leg 20 of the piston upper part 33 comes to rest on the web 21 of the lower piston part.

FIG. 5 shows the piston 31 after the joining process. Between the web 21 and the lower end of the leg 20 may be provided an optional support 9 for forming a soldering gap. A centering 10 of the piston upper part 33 on the piston lower part 32 is carried out as already described in the first embodiment, by the interaction of the inclined surface 6 with the lower end of the inner wall 7. In the soldering gap, formed by the support 9 and in the centering 10 can a positive, positive or cohesive connection between piston lower part 32 and piston upper part 33 take place, for example, a soldering or welding connection can be provided here.

After further processing steps, the finished piston 31 is shown in FIGS. 6 and 7. It can be seen that the centering 10 has been preserved after processing. In the processing of the edge region of the trough 11, the support 9 for the soldering gap, if it was present, is removed. The joint seams 17 between piston lower part 32 and upper piston part 33 can be seen. A ring field 6 was also worked out. The trough 11 has received its functional profile.

The joining method according to the invention for a piston lower part and a piston upper part is not limited to the exemplary embodiments described here.

LIST OF REFERENCE NUMBERS

1 piston

2 piston lower part

3 piston upper part / ring

4th edition

5 depot (e.g., for solder paste)

6 inclined surface / centering

7 interior wall

8 sliding surface

9 edition (for soldering gap)

10 centering

11 trough

12 troughs edge ring

13 cooling channel

14 collar

15 edition

16 ring field

7 joining

18 area

19 thighs

20 thighs

21 footbridge

31 pistons

32 piston lower part

33 piston upper part / ring

F joining direction

Claims

PATENT APPLICATION Joint connection on a two-part steel piston and joining process

1. piston (1, 31), in particular cooling channel piston for an internal combustion engine, comprising a piston lower part (2, 32) and a piston upper part (3, 33), which are connected in a joining process to the piston (1, 31), wherein the piston upper part (3, 33) at least one annular field (16) and an inner wall (7), characterized in that the lower piston part (2, 32) has a radially encircling inclined surface (6) at the end facing the piston upper part (3, 33), which cooperates with the inner wall (7) of the Koibenoberteiles (3, 33) in the joining process of the piston parts (2, 3, 32, 33) causes a centering (10).

Second piston (1, 31) according to claim 1, characterized in that the piston lower part (2, 32) has at least one sliding surface (8) which cooperates in the joining process with the inner wall (7) of the piston upper part (3, 33).

3. Piston (1, 31) according to one of the preceding claims, characterized in that in the region of at least one joint seam (17) at least one support (9) is provided for forming a gap.

4. piston (1, 31) according to one of the preceding claims, characterized in that the gap adjacent to the support (9) for receiving solder material is used.

5. piston (1, 31) according to any one of the preceding claims, characterized in that a depot (5), in particular for receiving solder material is provided.

6. Piston (1) according to one of the preceding claims, characterized in that on the piston upper part (3) a circumferential collar (14) is provided as a limitation in the joining process in cooperation with a support (15).

7. piston (1) according to any one of the preceding claims, characterized in that the collar (14) is removed after completion of the joining operation.

8. piston (1, 31) according to any one of the preceding claims, characterized in that the piston upper part (3, 33) at least one ring field (16) forms after the joining process.

9. A method for producing a piston (1, 31), in particular cooling channel piston for an internal combustion engine, comprising a piston lower part (2, 32) and a piston upper part (3, 33) which are connected in a joining process to the piston (1, 31) wherein the upper piston part (3, 33) has at least one annular field (16) and an inner wall (7), comprising the following steps:

- Provision of the piston upper part (3, 33) and the piston lower part (2, 32), - Plugs the piston parts (2, 3, 32, 33), characterized in that during the joining process, a centering (10) of piston upper part (3, 33 ) to lower piston part (2, 32).

10. The method according to claim 9, characterized in that at least one support (4, 9, 15) is removed for the joining operation in at least one further process step.