Piston Having Three Ring Grooves And A Further Groove Having A Joint

Abstract

A method for producing a cooling duct piston for an internal combustion engine having a cooling duct in its piston crown. A piston main body is produced with a collar which is circumferential and projects radially in the region of the piston crown. The collar is formed until its outer circumferential edge comes very closely or completely into contact with a bearing region of the piston lower part forming the cooling duct. At least one ring groove is introduced. A ring-free groove is further formed below the ring groove, wherein a dividing plane lies between the outer circumferential edge of the formed collar and an upper side of the piston lower part in the ring-free groove.

Claims

1. A method for producing a cooling duct piston for an internal combustion engine, which cooling duct piston has a cooling duct in a piston crown, wherein the piston crown is adjoined by a piston lower part having piston bosses, pin bores and piston skirts, wherein a piston main body is firstly produced with a collar which is circumferential and projects radially in the region of the piston crown, wherein the collar is formed in such a manner until an outer circumferential edge is positioned in one of very closely or completely into contact with a bearing region of the piston lower part, in order to form the cooling duct, and subsequently at least one ring groove is formed in the collar, characterized in that a ring-free groove is formed in the collar below the at least one ring groove, wherein a dividing plane lies in the ring-free groove between the outer circumferential edge of the formed collar and an upper side of the piston lower part.

2. The method of claim 1, wherein the outer circumferential edge is positioned very closely to the bearing region, and wherein the collar is configured and formed in such a manner that in the region of the dividing plane between the outer circumferential edge of the formed collar and an upper side of the piston lower part a gap is created.

3. The method of claim 1, wherein the collar is configured and formed in such a manner that in the region of the dividing plane the outer circumferential edge of the formed collar comes into contact with the upper side of the piston lower part.

4. The method of claim 1, wherein the ring-free groove is formed by a chip-removing machining process.

5. The method of claim 1, wherein the ring-free groove is formed by a non-cutting machining process.

6. The method of claim 1, wherein the ring-free groove is created by a forming of the outer circumferential edge of the formed collar and an upper side of the piston lower part.

7. The method of claim 6, wherein the step of creating the ring-free groove further comprises a subsequent chip-removing machining process.

8. The method of claim 1, wherein in the region of the dividing plane between the outer circumferential edge of the formed collar and an upper side of the piston lower part, a joining process is carried out.

9. The method of claim 8, wherein the joining process comprises one of a welding process, a soldering process, or a bonding process.

10. The method of claim 9 wherein the joining process comprises the welding process forming a welding bead, wherein the method further comprises removing the welding bead.

11. A method for producing a cooling duct piston for use in an internal combustion engine, the method comprising: forming a piston main body comprising: a collar including a radial outer circumferential edge; a lower part having an upper side; a piston stroke axis; further forming the collar to position the outer circumferential edge to one of directly adjacent to the lower part upper side or in direct contact with the lower part upper side defining a dividing plane and forming a cooling duct; forming a ring groove in the collar operable to receive a piston ring; forming a non-ring groove at the dividing plane positioned below the ring groove in a direction parallel to the piston stroke axis.

12. The method of claim 11 wherein the circumferential edge is directly adjacent to the lower part upper side defining a spatial gap between the collar outer circumferential edge and the lower part upper side, the gap in fluid communication with the cooling duct.

13. The method of claim 12 further comprising: joining the collar outer circumferential edge to the lower part upper side at the dividing plane.

14. The method of claim 13 wherein the step of joining comprises one of welding, soldering or bonding.

15. The method of claim 14 wherein the step of joining comprises welding, the method comprising forming a weld bead within the non-ring groove.

16. The method of claim 11 further comprising: joining the collar outer circumferential edge to the lower part upper side at the dividing plane.

17. The method of claim 11 wherein the step of forming the non-ring groove comprises one of a chip-removing machining, non-cutting machining or forming of the other circumferential edge of the formed collar and the lower part upper side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is an example of a prior art cooling duct piston.

[0023] FIGS. 2-5 are examples of a cooling duct piston produced according to the inventive method.

DETAILED DESCRIPTION

[0024] In terms of its production, a cooling duct piston 10 according to the exemplary embodiment is also based on the method described in DE 10 2004 031 513 A1.

[0025] The detail of the cooling duct piston 10, as shown in FIG. 2, is also once again based on the fact that a radially projecting and circumferential collar is initially provided by a piston main body 20. In a suitable method step, this initially projecting collar is formed in such a manner that from its initial orientation projecting roughly perpendicularly to the piston stroke axis it is formed in a roughly parallel orientation in relation thereto. The collar is thereby folded down at an angle of approximately 90, so that a circumferential, folded-down collar 30, as shown in FIG. 2, emanates from the piston main body 20. In the region of the folded-down collar 30, at least one ring groove 40 (in this case in the exemplary embodiment illustrated in FIG. 2, 3 ring grooves 40) is introduced at a given point in time. The piston main body 20 moreover has a piston lower part 50, so that a cooling duct 60 is created by the piston main body 20 along with the piston lower part 50 and the folded-down collar 30.

[0026] The forming of the collar 30 leads to a drawing closer or contact between the circumferential lower edge of the collar 30 and the upper side of the piston lower part 50 in the region of a dividing plane 70. The regions corresponding to one another of the collar 30 and the piston lower part 50 either form a gap in the region of the dividing plane or, as shown in FIG. 2, they come into contact in this region of the dividing plane 70 (small gap shown in FIG. 2 for purposes of illustration only).

[0027] Unlike in the case of the aforementioned exemplary embodiment according to FIG. 1, in which the dividing plane 7 lay either in a ring groove 4 having a piston ring or below the lowermost ring groove 4, according to the exemplary embodiment and according to the invention the dividing plane 70 is placed in the region of a ring-free groove 80. This ring-free groove 80 is created by forming the lower circumferential edge of the collar 30 and the corresponding upper side of the piston lower part 50 and/or is introduced by a corresponding machining step, in particular a chip-removing machining process. Consequently, the detail of the cooling duct piston 10, as depicted in FIG. 2, shows in principle a cooling duct piston 10 which is for the most part finished and ready for use (while it should be emphasized that reworking has taken place in order to bring the cooling duct piston 10 up to the required standard).

[0028] Consideration can also be given, however, to a further substance-bonding joining process in the region of the dividing plane 70, such as, for example, a welding process. In order to illustrate this further machining step, reference is made to FIG. 3. It is assumed that the cooling duct piston 10 adopts the state depicted in FIG. 2 following the forming of the collar 30. The substance-bonded joining process then takes place in the region of the ring-free groove 80 (based on FIG. 2), wherein a welding bead produced during this is not depicted. In a further process step, this welding bead is removed (and, if not already present, the ring-free groove 80 is introduced), so that the cooling duct piston 10 in the region of the ring-free groove 80 adopts the form depicted in FIG. 3. There is then a final reworking of the cooling duct piston 10 supplied in this way, in order to bring it up to the standard required for it to be installed in a cylinder of an internal combustion engine.

[0029] Finally, FIGS. 4 and 5 show a finished cooling duct piston 10 of this kind which is ready for operation. It can be seen that this cooling duct piston 10 has the cooling duct 60 in a piston crown 90 (and possibly, as depicted, a combustion bowl), wherein the piston crown 90 is adjoined in a manner known per se by the piston lower part 50 with piston bosses 100, pin bores 110 and piston skirts 120. Reference number 130 is used to denote a piston stroke axis, wherein perpendicularly thereto a pin bore axis not referred to in greater detail runs through the pin bores 110.

[0030] Ring groove should be understood to mean a circumferential groove which is located in a ring field of the cooling duct piston and into which a piston ring (for example, an oil ring) is inserted.

[0031] The outer circumferential edge of the circumferential collar should, in particular, be understood to mean the face which points radially outwards before the forming of the collar projecting from the piston main body and which, following its forming, points downwards (in the direction of the piston skirt) when observing the piston stroke axis.

LIST OF REFERENCE NUMBERS

[0032] 1. Cooling duct piston

[0033] 2. Piston main body

[0034] 3. Circumferential collar

[0035] 4. Ring groove

[0036] 5. Piston lower part

[0037] 6. Cooling duct

[0038] 7. Dividing plane

[0039] 10. Cooling duct piston

[0040] 20. Piston main body

[0041] 30. Circumferential collar

[0042] 40. Ring groove

[0043] 50. Piston lower part

[0044] 60. Cooling duct

[0045] 70. Dividing plane

[0046] 80. Ring-free groove

[0047] 90. Piston crown

[0048] 100. Piston boss

[0049] 110. Pin bore

[0050] 120. Piston skirt

[0051] 130. Piston stroke axis