Fluid injector

1. A fluid injector comprising

an actuator unit; and

a cartridge which comprises a recess, which on one of its open ends forms an injection nozzle and takes in a needle; wherein the needle comprises a first and second part with the first part being inserted into the recess and closing or opening the injection nozzle depending on the position of the first part, wherein the second part being coupled to the actuator unit on one of its free ends and being coupled to the first part via a coupling unit, which is arranged in positive connection to the first part and is joined to the second part;

wherein the actuator unit, the second part of the needle, and the first part of the needle are arranged substantially end-to-end in that order along an axial length of the fluid injector, such that movement of the actuator unit acts on the second part of the needle, which in turn acts on the first part of the needle to move the first part of the needle; and

wherein a receptance is formed in the first part of the needle and fixes a keeper in axial direction relative to the first part of the needle, and a coupling body, which has a recess, through which the first part of the needle protrudes and which takes in the keeper such that keeper fits substantially tightly within the recess to substantially prevent any radial movement of the keeper and the first part of the needle relative to the second part of the needle and with the coupling body being joined to the second part of the needle,

wherein the recess has an inner diameter, the first part of the needle has an outer diameter smaller than the inner diameter of the recess such that the first part of the needle can pass through the recess, and the keeper has an outer diameter larger than the inner diameter of the recess such that the keeper cannot pass through the recess.

2. A fluid injector according to claim 1 , wherein the coupling unit forms a spring rest, on which a return spring rests, that urges the needle in a position in which the injection nozzle is closed.

3. A fluid injector according to claim 1 , wherein the coupling unit is joined to the second part by welding.

4. A fluid injector comprising

an actuator unit;

a cartridge which comprises a recess, which on one of its open ends forms an injection nozzle; and

a needle comprising a first and second part with the first part being inserted into the recess and closing or opening the injection nozzle depending on the position of the first part, wherein the second part being coupled to the actuator unit on one of its free ends and being coupled to the first part via a coupling unit, which is arranged in positive connection to the first part and is joined to the second part;

wherein the actuator unit, the second part of the needle, and the first part of the needle are arranged substantially end-to-end in that order along an axial length of the fluid injector, such that movement of the actuator unit acts on the second part of the needle, which in turn acts on the first part of the needle to move the first part of the needle; and

wherein a receptance is formed in the first part of the needle and fixes a keeper in axial direction relative to the first part of the needle, and a coupling body, which has a recess, through which the first part of the needle protrudes and which takes in the keeper such that keeper fits substantially tightly within the recess to substantially prevent any radial movement of the keeper and the first part of the needle relative to the second part of the needle and with the coupling body being joined to the second part of the needle,

wherein the recess has an inner diameter, the first part of the needle has an outer diameter smaller than the inner diameter of the recess such that the first part of the needle can pass through the recess, and the keeper has an outer diameter larger than the inner diameter of the recess such that the keeper cannot pass through the recess.

5. A fluid injector according to claim 1 , wherein the coupling unit forms a spring rest, on which a return spring rests, that urges the needle in a position in which the injection nozzle is closed.

6. A fluid injector according to claim 4 , wherein the coupling unit is joined to the second part by welding.

7. A fluid injector comprising

an actuator unit;

a cartridge which comprises a recess, which on one of its open ends forms an injection nozzle;

a needle comprising a first and second part with the first part being inserted into the recess and closing or opening the injection nozzle depending on the position of the first part, wherein the second part being coupled to the actuator unit on one of its free ends and being coupled to the first part via a coupling unit, which is arranged in positive connection to the first part and is joined to the second part, wherein the coupling unit forms a spring rest, on which a return spring rests, that urges the needle in a position in which the injection nozzle is closed, and wherein the actuator unit, the second part of the needle, and the first part of the needle are arranged substantially end-to-end in that order along an axial length of the fluid injector; and

a receptance, which is formed in the first part of the needle and fixes a keeper in axial direction relative to the first part of the needle, and a coupling body, which has a recess, through which the first part of the needle protrudes and which takes in the keeper and fixes it in the radial direction relative to the first part of the needle and with the coupling body being joined to the second part of the needle,

wherein the recess has an inner diameter, the first part of the needle has an outer diameter smaller than the inner diameter of the recess such that the first part of the needle can pass through the recess, and the keeper has an outer diameter larger than the inner diameter of the recess such that the keeper cannot pass through the recess.

8. A fluid injector according to claim 7 , wherein the coupling unit is joined to the second part by welding.