Lighting device with mechanical fastening part

1. A lighting device comprising:

an envelope,

a light generating unit,

a stem arranged to support the light generating unit inside the envelope, and

a mechanical fastening part arranged to fasten the light generating unit at the stem,

wherein said light generating unit being arranged to at least partially surround the stem, thereby forming a chimney-like structure,

wherein the mechanical fastening part comprises at least one protrusion and the light generating unit comprises at least one hole adapted to mate with the at least one protrusion so as to fasten the light generating unit to the mechanical fastening part, and

wherein the stem is light transmissive.

2. The lighting device as defined in claim 1 , wherein the at least one hole comprises a through hole.

3. The lighting device as defined in claim 1 , wherein the mechanical fastening part comprises a plurality of protrusions arranged around a longitudinal axis of the stem.

4. The lighting device as defined in claim 1 , wherein the light generating unit is arranged to at least partially surround the mechanical fastening part.

5. The lighting device as defined in claim 1 , wherein the light generating unit comprises one or more carriers and one or more solid state light sources arranged at the one or more carriers.

6. The lighting device as defined in claim 5 , wherein the at least one hole is arranged in the carrier.

7. The lighting device as defined in claim 1 , wherein the mechanical fastening part comprises a metal sheet.

8. The lighting device as defined in claim 7 , wherein the metal sheet is folded or deep drawn so as to define at least one geometrical feature adapted to fasten the mechanical fastening part to the stem.

9. The lighting device as defined in claim 7 , wherein an edge of the metal sheet is shaped so as to define the at least one protrusion.

10. The lighting device as defined in claim 1 , wherein the stem comprises a geometrical feature arranged to mate with a geometrical feature of the mechanical fastening part so as to fasten the mechanical fastening part to the stem.

11. The lighting device as defined in claim 1 , wherein the stem comprises glass.

12. The lighting device as defined in claim 1 , further comprising a cap connected to the envelope and supporting the stem in the envelope.

13. The lighting device as defined in claim 1 , wherein the at least one protrusion is shaped so as to lock the light generating unit to the mechanical fastening part.

14. A method of manufacturing a lighting device, the method comprising:

arranging a mechanical fastening part on a stem, the mechanical fastening part comprising at least one protrusion, wherein the stem is light transmissive,

arranging said light generating unit to at least partially surround the stem, thereby forming a chimney-like structure,

arranging said light generating unit comprising at least one hole on the mechanical fastening part such that the at least one hole mates with the at least one protrusion, thereby fastening the light generating unit to the mechanical fastening part, and

arranging the stem at least partially inside an envelope such that the light generating unit is supported by the stem in the envelope.