PISTON FOR AN INTERNAL COMBUSTION ENGINE AND INTERNAL COMBUSTION ENGINE

Abstract

A piston for an internal combustion engine may include a piston crown and a heat management coating. The heat management coating may be disposed on at least a region of an outer surface of the piston crown. The heat management coating may include a base layer and a functional layer. The base layer may be disposed between the piston crown and the functional layer, and may be adjoining the outer surface of the piston crown. The base layer may have a base layer matrix including a first polysilazane. The functional layer may have a functional layer matrix including a second polysilazane. The second polysilazane may be different from the first polysilazane.

Claims

1. A piston for an internal combustion engine, comprising: a piston crown having an outer surface; a heat management coating disposed on at least a region of the outer surface of the piston crown; the heat management coating including a base layer and a functional layer; the base layer disposed between the piston crown and the functional layer, and adjoining the outer surface of the piston crown; the base layer having a base layer matrix including a first polysilazane; the functional layer having a functional layer matrix including a second polysilazane; and wherein the second polysilazane is different from the first polysilazane.

2. The piston according to claim 1, wherein one of the first polysilazane and the second polysilazane is an inorganic polysilazane and the other of the first polysilazane and the second polysilazane is an organic polysilazane.

3. A piston for an internal combustion engine, comprising: a piston having an outer surface; a heat management coating disposed on at least a region of the outer surface of the piston crown; the heat management coating including a base layer and a functional layer; the base layer disposed between the piston crown and the functional layer, and adjoining the outer surface of the piston crown; the base layer including at least one of (i) nickel and (ii) silicon dioxide filled with a plurality of aluminum flakes; and the functional layer having a functional layer matrix including an organic polysilazane.

4. The piston according to claim 1, wherein the base layer has a base layer thickness, measured at a right angler to the outer surface of the piston crown, of 0.2 micrometer to 2 micrometer.

5. The piston according to claim 1, wherein the functional layer has a functional layer thickness, measured at a right angle to the outer surface of the piston crown, of 50 micrometers to 100 micrometers

6. The piston according to claim 1, wherein the functional layer further includes a plurality of hollow particles embedded in the functional layer matrix in the manner of a filler.

7. The piston according to claim 6, wherein: the plurality of hollow particles are structured as a plurality of hollow spheres; and the plurality of hollow particles include glass.

8. The piston according to claim 1, wherein the functional layer further includes a plurality of metal flakes embedded in the functional layer matrix in the manner of a filler.

9. The piston according to claim 1, wherein the functional layer further includes mica embedded in the functional layer matrix in the manner of a filler.

10. The piston according to claim 1, wherein the heat management coating further includes an outer layer disposed on the functional layer facing away from the piston crown.

11. The piston according to claim 10, wherein the outer layer includes an inorganic polysilazane.

12. The piston according to claim 10, wherein the outer layer includes a metal.

13. The piston according to claim 10, wherein the outer layer has an outer layer thickness, measured at a right angle to the outer surface of the piston crown, of 5 micrometers to 10 micrometers.

14. The piston according to claim 10, wherein the outer layer at least one of (i) is pore-free and (ii) has closed pores, such that the outer layer covers the functional layer in an essentially gas-impermeable manner.

15. An internal combustion engine, comprising: a cylinder; the piston according to claim 1; wherein the piston is guided movably within the cylinder in a stroke direction; and wherein the outer surface of the piston, together with the cylinder, partly bounds a combustion chamber.

16. The piston according to claim 1, wherein the piston crown is composed of a piston material that includes at least one of an aluminum alloy and an iron alloy.

17. The piston according to claim 4, wherein the base layer thickness is 0.2 micrometer to 0.6 micrometer.

18. The piston according to claim 5, wherein the functional layer thickness is 50 micrometers to 70 micrometers.

19. The piston according to claim 10, wherein the outer layer is thermally stable up to at least 650° C.

20. An internal combustion engine, comprising: a cylinder; the piston according to claim 3; wherein the piston is guided movably within the cylinder in a stroke direction; and wherein the outer surface of the piston, together with the cylinder, partly bounds a combustion chamber.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0028] The sole FIGURE shows a rough schematic of an example of an internal combustion engine of the invention.

DETAILED DESCRIPTION

[0029] The sole FIGURE shows a rough schematic of an example of an internal combustion engine 11 of the invention, usable for a motor vehicle. The internal combustion engine 11 comprises a cylinder 12. Within the cylinder 12 of the internal combustion engine 11 is guided a piston 1 of the invention, likewise shown by way of example in the FIGURE. The piston 1, together with the cylinder 12, partly bounds a combustion chamber of the internal combustion engine 11 by an outer surface 2, for example at the end face, of the piston 1.

[0030] The FIGURE illustrates a piston 1 in a first aspect of the invention. According to this, the piston 1 has a piston crown 3 comprising the outer surface 2. The piston 1 also comprises a heat management coating 4 disposed at least in some regions of the outer surface 2 of the piston crown 3. The heat management coating 4 of the piston 1 comprises a base layer 5 and a functional layer 6. The base layer 5 is disposed between the piston crown 3 and the functional layer 6, adjoining the outer surface 2 of the piston crown 3. The base layer 5 comprises a base layer matrix including a first polysilazane or consisting of the first polysilazane. The functional layer 6 comprises a functional layer matrix including a second polysilazane—different from the first polysilazane—or consists of the second polysilazane. In the first aspect of the invention, the first polysilazane is an inorganic polysilazane and the second polysilazane is an organic polysilazane, or vice versa.

[0031] The FIGURE also illustrates, by way of example, a piston 1 for an internal combustion engine 11 in a second aspect of the invention, which is usable for a motor vehicle. According to this, the piston 1 comprises a piston crown 3 having the outer surface 2. The piston 1 further comprises a heat management coating 4 disposed at least in some regions of the outer surface 2 of the piston crown 3. The heat management coating 4 of the piston 1 comprises a base layer 5 and a functional layer 6. The base layer 5 is disposed between the piston crown 3 and the functional layer 6, adjoining the outer surface 2 of the piston crown 3. In the second aspect of the invention, the base layer 5 comprises nickel, or silicon dioxide filled with aluminum flakes, or consists of nickel, or silicon dioxide filled with aluminum flakes. The functional layer 6 comprises a functional layer matrix including organic polysilazane or consists of organic polysilazane.

[0032] As can also be appreciated with reference to the FIGURE, the base layer 5 of the piston 1, in both aspects of the invention, has a base layer thickness 7 measured at right angles to the outer surface 2 of the piston crown 3. The base layer thickness 7 of the base layer 5 is 0.2 μm to 2 μm, and in the example shown 0.2 μm to 0.6 μm. The functional layer 6 has a functional layer thickness 8 measured at right angles to the outer surface 2 of the piston crown 3. The functional layer thickness 8 of the functional layer 6 is 50 μm to 100 μm, and in the example shown 50 μm to 70 μm. The functional layer 8 comprises hollow particles embedded in the functional layer matrix of the functional layer 8 in the manner of a filler. The hollow particles take the form of hollow spheres. Such hollow spheres may, as a result of the manufacture, have a geometry slightly different from an ideal sphere. The hollow particles comprise glass or consist of glass. The functional layer 6 of the heat management coating 4 also comprises metal flakes embedded in the functional layer matrix of the functional layer 6 in the manner of a filler. Furthermore, the functional layer 6 comprises mica embedded in the functional layer matrix in the manner of a filler. The mica may be formed by mica platelets, meaning that the mica particles in this variant each have the geometry of a platelet.

[0033] It is also shown in the FIGURE that the heat management coating 4 comprises an outer layer 9 disposed on the functional layer 6, facing away from the piston crown 3. The outer layer 9 in the example shown is thermally stable up to at least 650° C. The outer layer 9 comprises an inorganic polysilazane or consists of an inorganic polysilazane. Alternatively, the outer layer comprises a metal or consists of a metal. The outer layer 9 has an outer layer thickness 10 measured at right angles to the outer surface 2 of the piston crown 3. The outer layer thickness 10 of the outer layer 9 is 5 μm to 10 μm. The outer layer 9 is pore-free or has closed pores. This means that the outer layer 9 has no pores or has solely closed pores. The outer layer 9 is in pore-free form or has closed pores in such a way that the outer layer 9 covers the functional layer 6 of the heat management coating 4 in an essentially gas-impermeable manner.

[0034] The piston crown 3 of the piston 1 comprises, for example, a piston material including an aluminum alloy or consists of a piston material including such an aluminum alloy. Alternatively, the piston crown 3 of the piston 1 comprises a piston material including an iron alloy or consists of a piston material including such an iron alloy.