PISTON OF TWO-PIECE CONSTRUCTION FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A piston for an internal combustion engine, configured as a gallery-cooled piston of two-piece construction includes a main body and a ring element. The ring element which has a ring zone and a fire land encloses a cooling gallery on the outside, which cooling gallery is delimited on the inside by an intermediate wall which separates the cooling gallery from a combustion chamber recess which is made in a piston head of the main body. The main body and the ring element together form two circumferential dividing planes which are offset with respect to one another, to which end in each case two interacting joining webs of the ring element and of the main body are connected with a material-to-material bond.

Claims

1. A piston for an internal combustion engine configured as a cooling-gallery piston of two-piece construction that includes a main body and a ring element, wherein the ring element with a ring belt and a top land encloses on the outside a cooling gallery delimited on the inside by an intermediate wall dividing the cooling gallery from a combustion bowl introduced into a piston crown of the main body and the ring element is joined in a material-to-material bond to the main body characterized in that the main body and the ring element jointly form two circumferential dividing planes offset to each other, to which end two matching, interacting joining webs of the ring element and the main body are joined in a material-to-material bond.

2. The piston from claim 1, wherein the dividing planes run between the ring element and the main body diverging from one another or matching vertically or horizontally.

3. The piston from claim 1, wherein the dividing planes are aligned obliquely or inclined.

4. The piston from claim 1 wherein a vertically aligned dividing plane and a horizontally aligned dividing plane are provided between the ring element and the main body.

5. The piston from claim 4, wherein a height offset H results between the vertically aligned dividing plane assigned to the piston crown and the horizontally aligned dividing plane.

6. The piston from claim 1, wherein the main body forms a circumferential step on the outside whose joining web running concentric to the longitudinal axis of the piston is enclosed at least in sections by the joining web of the ring element.

7. The piston from claim 1, wherein the matching joining webs of the ring element and the main body are dimensioned at least approximately equal.

8. The piston from claim 1, wherein the main body and the ring element are produced from a matching material or from different materials.

9. A method for producing a piston for an internal combustion engine, configured as a cooling-gallery piston of two-piece construction including a main body and a ring element , characterized by producing a main body and a ring element as blanks by forging or casting or by stamping from a semi-finished material from a steel material; pre-machining the main body and the ring element including introducing a combustion bowl into the main body and creating a ring belt; joining two matching joining webs of the main body and the ring element, which respectively form a dividing plane, by a material-to-material bond; and final finish machining of the piston.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0019] Additional features can be found in the following description and the drawings which show aspects of the present piston. Unless otherwise stated, identical or functionally identical components are given the same reference numerals.

[0020] FIG. 1 shows a first aspect of a piston in a sectional view;

[0021] FIG. 2 shows a second aspect of a piston in a sectional view;

[0022] FIG. 3 shows a third aspect of a piston in a sectional view;

[0023] FIG. 4 shows a fourth aspect of a piston in a sectional view.

DETAILED DESCRIPTION

[0024] FIG. 1 shows a sectional view of a piston 1 produced as one piece comprising a main body 2 and a ring element 3 that are connected by joining webs 6a, 6b; 7a, 7b forming dividing planes 4a, 5a. The joining webs 6a, 6b; 7a, 7b are joined in a material-to-material bond in the area of the dividing planes 4a, 5a by means of friction welding.

[0025] For example, multi-orbital friction welding is employed in which, because of the extremely small, circular orbital movements, no, or only minor, weld beads 8, 9 are formed in the area of the dividing planes 4a, 5a that require no, or only minor, reworking. The wall thickness S1, S2 of the joining webs 6a, 6b and the joining webs 7a, 7b is can be constant as far as possible. A maximum height offset H results between the vertically aligned dividing plane 5a and the horizontally running dividing plane 4a. The main body 2 of the piston 1 includes a combustion bowl 12 introduced into a piston crown 10 eccentric or rotationally symmetrical to a longitudinal axis 11. A piston skirt 13 of the main body 2 includes two diametrically opposed piston pin bores 4 that are intended to receive a piston pin (not shown). An intermediate wall 16 surrounding the combustion bowl 12 delimits a cooling gallery 15 on the inside that is enclosed on the outside by the ring element 3. The cooling gallery 15 is closed circumferentially by the main body 2 with the ring element 3 after welding has been performed. When the engine is operating, a cooling medium can be selectively applied to the cooling gallery 15 through at least one inlet and one outlet (not shown). The ring element 3 has a top land 17 on the piston crown side to which a ring belt 18 is attached with ring grooves 19 that are intended to receive piston rings (not shown).

[0026] FIGS. 2 to 4 show alternative aspects of the piston 1, wherein matching reference numerals are used for identical or identically functioning components. The following descriptions of FIGS. 2 to 4 are largely limited to differences in features compared with FIG. 1.

[0027] In accordance with FIG. 2, the piston 1 includes two vertically aligned dividing planes 4b, 5a between the main body 2 and the ring element 3. Dividing plane 4b is formed by a step 20 of the main body 2 that is enclosed on the outside by an end section of the ring element 3. An overlapping area of the joining webs 7a, 7b of the interacting components, the main body 2 and the ring element 3, defines the dividing plane 4b.

[0028] FIG. 3 illustrates shows the piston 1, the construction of which largely matches the illustration in FIG. 2. The piston 1 in FIG. 3 shows, in addition to the dividing plane 4b from FIG. 2, the horizontally running dividing plane 5b assigned to the intermediate wall 16 said planes being formed by the joining webs 21a, 21b. If the components forming the piston 1 are joined axially, the step 20 of the main body 2 can be used to center the ring element 3.

[0029] The piston 1 in FIG. 4 comprises two inclined, or oblique, dividing planes 4c, 5c between the main body 2 and the ring element 3. As an alternative to dividing planes 4c, 5c from FIG. 4 that run on a matching incline, it is possible that the dividing planes 4c, 5c run counter to each other.