Cooling of a piston by means of sodium-filled tubes

Abstract

Disclosed is an internal combustion engine piston wherein at least one space is formed into which a coolant is installed. In one example, the coolant is first introduced into a coolant container and the coolant container is thereafter inserted into the at least one space in the piston. In one example, the coolant is an alkali metal consisting of sodium.

Claims

1. A method for the production of a piston of a combustion engine, having an upper part with a ring zone and a piston skirt adjoining the upper part, the piston upper part and the skirt defining a central region, the method comprising: forming at least two elongated spaces obliquely positioned in the piston and aligned in a direction of the central region; installing the coolant into each of at least two coolant containers; and installing each of the at least two coolant containers into one of the at least two spaces in the piston.

2. The method of claim 1 wherein the central region defines a central region opening, the forming of each of the at least two elongated spaces further comprising forming an opening positioned in the central region opening in fluid flow communication with, and accessible to receive a respective container through, the central region opening; and installing a closure element in the central region opening operable to close the at least two spaces respective opening.

3. The method of claim 1 further comprising: fixedly engaging each of the at least two coolant containers inside one of the at least two spaces in the piston.

4. The method of claim 1 wherein forming the at least two elongated spaces aligned in a direction of the central region further comprising: forming the at least two spaces such that a longitudinal axis of each of the at least two spaces intersect in the piston central region.

5. A combustion engine piston comprising: an upper part having a ring zone; a piston skirt connected to the upper part, the piston upper part and skirt defining a central region; at least two elongated spaces defined by the piston, each elongated space is obliquely positioned and aligned in a direction of the central region; and at least two coolant containers operable to first receive and house a coolant, each of the at least two coolant containers and received coolant are respectively positioned in one of the at least two spaces.

6. The piston of claim 5, wherein after insertion into one of the respective at least two spaces, the coolant container is fixed in its position in the respective space.

7. The piston of claim 5 wherein the coolant container further comprises an elongated and cylindrical body.

8. The piston of claim 7 wherein the central region defines a central region opening and each of the at least two spaces each defining a longitudinal axis and an opening, wherein the openings are positioned in, are in fluid flow communication with, and are accessible to receive a respective container through the piston central region opening.

9. The piston of claim 8 further comprising a closure element positioned in the central region opening operable to close each of the at least two space openings after the insertion of the respective coolant container in the respective space.

10. The piston of claim 9 wherein the coolant comprises an alkali metal.

11. The piston of claim 9 wherein the obliquely positioned at least two spaces respective longitudinal axes intersect in the piston central region.

12. The piston of claim 9 wherein the at least two spaces respective openings are positioned at a height above the piston pin bores.

13. The piston of claim 7 wherein the at least two spaces comprises a plurality of spaces each defining an opening, wherein the plurality of spaces openings are positioned at a piston outer wall.

14. The piston of claim 13 wherein the obliquely positioned at least two spaces each defining a longitudinal axis, and wherein the plurality of spaces aligned in the direction of the central region comprises the respective longitudinal axis intersecting in the piston central region.

15. A method for producing a combustion engine piston having an upper part including a ring zone, a piston skirt connected to the upper part, the upper part and the skirt defining a central region further defining a central region opening, the method comprising: forming a plurality of cooling spaces in the piston, each of the plurality of cooling spaces obliquely positioned and aligned in a direction of the central region opening, each of the plurality of cooling spaces defining an opening; installing a coolant in a plurality of coolant containers, the plurality of coolant containers separate and independent of the plurality of cooling spaces; sealingly closing the plurality of coolant containers preventing the coolant from exiting the plurality of coolant containers; installing the plurality of coolant containers including the coolant in respective of the plurality of cooling spaces; and preventing the coolant containers from exiting the cooling spaces.

16. The method of claim 15 wherein the forming of the plurality of cooling spaces and respective opening further comprises: forming the opening for each of the plurality of cooling spaces in a central region opening of the piston, each of the cooling spaces respective openings accessible to receive a container through the central region opening.

17. The method of claim 16 wherein preventing the coolant containers from exiting the cooling spaces comprises: installing a closure element positioned in the central region opening, the closure element operable to close the plurality of cooling spaces respective openings.

18. The method of claim 15 wherein the forming of the plurality of cooling spaces and respective opening further comprises: forming the opening for each of the plurality of cooling spaces in an outer wall of the piston.

19. The method of claim 15 wherein installing the cooling containers in the respective of plurality of cooling spaces comprises casting the plurality of cooling containers in the piston.

20. The method of claim 15 wherein preventing the coolant containers from exiting the cooling spaces comprises: fixedly securing the plurality of coolant containers in a respective of the plurality of coolant spaces.

Description

DETAILED DESCRIPTION

(1) Reference numeral 1 indicates, by way of example, a one-piece piston 1, which has an upper part 2. A piston skirt 3 adjoins the upper part 2, wherein, in this design of the piston, the two opposite sections of the piston skirt 3 are connected by connecting walls 4, in which a pin bore 5 is also arranged. The pin bores 5 to receive the ends of a piston pin can be present but do not have to be present. The ends of the piston pin can also be arranged in some other way on the lower side of the upper part 2. In a manner known per se, the upper part 2 has a ring zone 6, wherein a central region (FIG. 1) is denoted by 7 in the inner region of the piston 1.

(2) A combustion chamber recess 8 can be present in the upper part 2 of the piston 1, as can a cooling passage 9 running around in the form of a ring. The combustion chamber recess 8 and/or the cooling passage 9 can, but need not be, present, depending on the intended use of the piston 1.

(3) A closure for openings 11 of spaces 12 situated within the piston 1 is indicated by 10 in FIG. 1.

(4) Considering FIG. 2, it becomes clear that, in principle, the at least one space 12, in this case a plurality of spaces 12, is arranged in the piston 1, i.e. within the solid material thereof. While, in FIG. 1, it is assumed that the openings 11 of the spaces 12 are accessible from the central region 7 (inner region of the piston 1), FIG. 2 illustrates that the openings 11 of the spaces 12 are accessible from the outer region of the piston 1 (e.g. from the connecting wall 4 or the piston skirt 3).

(5) Irrespective of the direction from where the spaces 12 are accessible and where the openings 11 (insertion openings) thereof are located, the spaces 12 are thus introduced in the required numbers into the main body (solid material) of the piston after the production of the piston 1 (to be more precise of a piston blank) or during production itself. As already described, introduction can be accomplished by means of lost cores which are flushed out. Instead, the respective space 12 can be introduced by suitable methods, e.g. drilling, milling or the like, after the production of the piston blank. This can be seen, for example, from the piston shown in FIG. 2, where the spaces 12 are arranged obliquely in the piston 1 and are aligned in the direction of the central region 7.

(6) After a piston as shown in FIG. 2 has been prepared, coolant containers 13 that have previously been produced and filled with coolant are inserted into the spaces 12 provided for them, as illustrated in FIG. 3. After insertion, the associated openings 11 of the space 12 are closed, or the respective coolant container 13 is inserted into the space 12 in such a way that it is fixed permanently in its position there after the completion of the insertion process. It is absolutely imperative that this fixing in position should be performed in such a way that the coolant container 13 cannot move out of the space 12 during the upward and downward movement of the piston 1 in the cylinder of the combustion engine.

(7) As can be seen in FIGS. 2 and 3, the spaces 12 and accordingly also the coolant containers 13 are of elongate and cylindrical configuration. This elongate and cylindrical configuration enables the coolant container 13 to be produced in a simple manner by using tubular material, which is closed at one end, for example, and then filled with the coolant, after which, in turn, the other end is closed gas tightly. Moreover, this elongate configuration has the advantage that the strength of the piston 1 is weakened only slightly, if at all, when the spaces 12 are introduced. It can be regarded as a further advantage that, by virtue of the elongate extent of the coolant container 12, very good heat transfer can take place from the regions which are highly stressed in terms of temperature (in the illustrative example the internally situated dome of the combustion chamber recess 8, for example) in the direction of regions which are less highly stressed in terms of temperature.

(8) To fill the coolant container 12 and for heat transfer, any suitable coolant may be considered. Alkali metals, e.g. sodium, are of particular advantage since they have very good heat transfer in the temperature working range of the piston 1.

LIST OF REFERENCE SIGNS

(9) 1. piston 2. upper part 3. piston skirt 4. connecting wall 5. pin bore 6. ring zone 7. central region 8. combustion chamber recess 9. cooling passage 10. closure 11. openings 12. space 13. coolant container