PRECHAMBER DEVICE FOR COMBUSTION ENGINE

Abstract

Disclosed is a prechamber device for a combustion engine. The prechamber device comprises a prechamber body circumferentially enclosing a prechamber cavity, a nozzle body extending from the prechamber body and disposed at a first axial end of the prechamber device, wherein an interior of the nozzle body is in fluid communication with and provides an appendix of the prechamber cavity. The prechamber body and the nozzle body are provided as a wall comprising an inner surface and an outer surface and comprise a first material. A core member of a second material is enclosed inside the wall between the inner surface and the outer surface and axially extending inside the nozzle body, enclosed by the first material.

Claims

1. A prechamber device for a combustion engine, comprising: the prechamber device extending from a first axial end to a second axial end along an axial direction; a prechamber body circumferentially enclosing a prechamber cavity; a nozzle body extending from the prechamber body and disposed at a first axial end of the prechamber device as an appendix of the prechamber body, with an interior of the nozzle body in fluid communication with and providing an appendix of the prechamber cavity; nozzle openings provided through the nozzle body from the interior to the exterior of the nozzle body; the prechamber body and the nozzle body provided as a wall comprising an inner surface and an outer surface; the prechamber body and the nozzle body comprising a first material forming the inner surface and the outer surface of the wall, and a core member of a second material enclosed inside the wall between the inner surface and the outer surface, axially extending inside the nozzle body wall, and enclosed by the first material; and the core member comprising at least one cross section integrally spanning a circumference of the prechamber device.

2. The prechamber device according to claim 1, wherein the first material has a first thermal conductivity and the second material has a second thermal conductivity, with the second thermal conductivity being larger than the first thermal conductivity.

3. The prechamber device according to claim 1, wherein the first material has first mechanical strength parameters and the second material has second mechanical strength parameters, with at least one first mechanical strength parameter of the first mechanical strength parameters exceeding a corresponding second mechanical strength parameter of the second mechanical strength parameters.

4. The prechamber device according to claim 1, wherein the first material has a first melting point and the second material has a second melting point, with the second melting point lower than the first melting point.

5. The prechamber device according to claim 1, wherein the first material has a first corrosion and/or erosion resistance and the second material has a second corrosion and/or erosion resistance, with the second corrosion and/or erosion resistances lower than the first corrosion and/or erosion resistance.

6. The prechamber device according to claim 1, wherein the core member is restricted to the nozzle body.

7. The prechamber device according to claim 1, wherein the core member axially extends through at least a part of the nozzle body and a part of the prechamber body.

8. The prechamber device according to claim 1, wherein the core member is shaped as a conduit enclosed by a solid wall.

9. The prechamber device according to claim 1, wherein the core member is shaped as one of a crown and a cage.

10. The prechamber device according to claim 1, wherein the second material has a melting point to liquify during operation of the prechamber device.

11. A method of manufacturing a prechamber device according to claim 1, comprising: providing a solid core member of the second material; and disposing the first material around the core member by an additive manufacturing method.

12. A method of manufacturing a prechamber device according to claim 1, comprising: manufacturing the prechamber device using an additive manufacturing method; and changing the material disposed for the additive manufacturing method during the manufacturing of the core member.

13. A cylinder head, comprising: a prechamber device according to claim 1.

14. A reciprocating engine, comprising: a cylinder head according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The subject matter of the present disclosure is now to be explained in more detail by means of selected exemplary embodiments shown in the accompanying drawings. The figures show

[0022] FIG. 1 a sectional view of a first exemplary embodiment of a prechamber device of the type herein disclosed; and

[0023] FIG. 2 a sectional view of a second exemplary embodiment of a prechamber device of the type herein disclosed.

[0024] It is understood that the drawings are highly schematic, and details not required for instruction purposes may have been omitted for the ease of understanding and depiction. It is further understood that the drawings show only selected, illustrative embodiments, and embodiments not shown may still be well within the scope of the herein disclosed and/or claimed subject matter.

EXEMPLARY MODES OF CARRYING OUT THE TEACHING OF THE PRESENT DISCLOSURE

[0025] FIG. 1 shows, in a sectional view, a first exemplary embodiment of a prechamber device according to the teaching of the present disclosure. Prechamber device 1 comprises prechamber body 13 and nozzle body 14 extending from prechamber body 13 and being disposed at one axial end of the prechamber device. An axis of the prechamber device is denoted at 11. A prechamber cavity 12 is formed inside the prechamber device and extends axially into the nozzle body, forming an interior of the nozzle body. Nozzle openings 15 are provided in nozzle body 14, and provide fluid communication between the interior of the nozzle body and an exterior of the nozzle body. Prechamber cavity 12 is delimited circumferentially, and at a nozzle-sided axial end, by a wall. It is noted that prechamber device 1 is open at an axial end opposed the nozzle body, so as to receive an ignition device, such as a spark plug, in prechamber cavity 12. The wall delimiting prechamber cavity 12 comprises inner surface 16 adjacent prechamber cavity 12, and outer surface 17. The wall is made from a first material. This first material forms the inner and outer surface, and generally forms the entire external surface of the wall, or of prechamber device 1, respectively. A core member 18 is provided and enclosed inside the wall. Core member 18 is hermetically enclosed inside the wall. Core member 18 is disposed between inner surface 16 and outer surface 17 of the wall, wherein inner surface 16 and outer surface 17 are formed by a first material. Core member 18 comprises, or is made from, respectively, a second material different from the first material from which the wall and the inner and outer surfaces are formed. Core member 18 has no external surface and is entirely enclosed by first material. Core member 18 extends circumferentially, and in particular integrally, uninterrupted, around the entire circumferential extent of prechamber device 1. In the exemplary embodiment shown in FIG. 1, core member 18 may be a hollow cylinder. Core member 18 may for non-limiting instances be made from aluminum or copper as the second material, having a relatively high heat conductivity and a relatively low mechanical strength. The wall in which core member 18 is enclosed may be made from any material yielding a comparatively higher mechanical strength, in particular at elevated temperatures, and a comparatively lower heat conductivity. Thus, the mechanically weaker core member is firmly enclosed and supported inside a mechanically stronger wall, and thus does not, or only insignificantly, bear mechanical load. It is further entirely protected from any chemical or physical corrosive and/or abrasive influences. On the other hand, it serves to intensify heat conduction inside prechamber device 1, thus to reduce temperature gradients occurring during operation, reduce thermally induced stresses, and in turn thus supports mechanical integrity of the prechamber device. As the skilled person will readily appreciate, during operation of a prechamber device heat intake into the material of the prechamber device is elevated at the nozzle body, and at the tip of the nozzle body, and further occurs from inner surface 16. This is caused by combustion inside prechamber cavity 12 and hot gases and plasma being ejected through nozzle openings 15, thus intensifying heat intake into the material surrounding the nozzle openings, and further heat intake from the combustion chamber of the engine at the tip of nozzle body 14. On the other hand, outer surface 17 of prechamber body 13 is received in a cooled cylinder head. Thus, temperature gradients result, with the temperature decreasing from the tip of nozzle body 14 to the prechamber body 13 in an axial direction on the one hand, and from inner surface 16 to outer surface 17 in a radial direction on the other hand. Core member 18, comprising a material of a comparatively higher heat conductivity than the material of the surrounding wall, intensifies heat conduction, or reduces the temperature gradient required to drive a certain heat flux, respectively. As a result, the temperature gradients, and along with that, thermally induced stresses, are reduced, also in the wall. In that core member 18 extends axially on the one hand and spans the circumference of prechamber device 1 on the other hand, axial temperature gradients are reduced, and circumferential temperature gradients are reduced if not avoided. It is noted that core member 18 may in particular be circumferentially closed, or exhibit at least one cross-section in which it is circumferentially closed, so as to further support evening out the temperature distribution along the circumference of prechamber device 1.

[0026] In a second exemplary embodiment shown in FIG. 2, core member 18 exhibits a significantly larger axial extent than in the embodiment of FIG. 1. Core member 18, in this illustrative and exemplary embodiment, extends from inside nozzle body 14 far into prechamber body 13. In order to enable this, in particular around the tapering section of prechamber cavity 12, core member 18 is essentially funnel-shaped, with a frustoconical section inside prechamber body 13 and surrounding the tapering section of prechamber cavity 12, and a cylindrical section extending into nozzle body 14. The skilled person will appreciate that the enlarged core member in the embodiment of FIG. 2 further intensifies heat conduction inside prechamber device 1. The skilled person will by standard calculations of the heat transfer and temperature distribution for the operation of a prechamber device in a specific engine or cylinder head readily determine an optimum size and shape of core member 18.

[0027] While the subject matter of the disclosure has been explained by means of exemplary embodiments, it is understood that these are in no way intended to limit the scope of the claimed invention. It will be appreciated that the claims cover embodiments not explicitly shown or disclosed herein, and embodiments deviating from those disclosed in the exemplary modes of carrying out the teaching of the present disclosure will still be covered by the claims.