Plug assembly for high-pressure valve

1. A plug assembly for a high-pressure valve forming part of a common rail injection circuit of an internal combustion engine, the valve being of the type with a tubular body extending along a longitudinal axis and in which, under the action of a piloted actuator, a needle moves longitudinally between a closed position and an open position, the plug assembly comprising:

a plug having a flat part able to be fixed onto the tubular body transversally to the longitudinal axis, and

a spring applying a force to the needle to bias the needle axially towards the closed position,

wherein the spring is fixed to the plug forming with it an integrated assembly, and

wherein the plug includes an annular protuberance which extends axially from the flat part so as to form a bearing for guiding the needle longitudinally, the spring being fixed onto the annular protuberance.

2. A plug assembly as described in claim 1 in which the spring is of the helical type and in which the annular protuberance includes a jamming section having an external diameter which is slightly greater than an internal diameter of the spring so that the spring is fixed by jamming of a turn of the spring around the jamming section.

3. A plug assembly as described in claim 2 in which the jamming section is arranged at a base of the annular protuberance close to the flat part of the plug, the annular protuberance including a guiding section which extends beyond the jamming section and the external diameter of which is less than the internal diameter of the spring so as to act, during assembly, as a guide for the spring without hampering the movements of the spring during compression and expansion phases.

4. A plug assembly as described in claim 3 in which the guiding section and the jamming section are joined by a surface in the form of a truncated cone.

5. A plug assembly as described in claim 1 in which the protuberance is formed in one piece with the plug.

6. A plug assembly as described claim 1 in which the spring is fixed to the plug by welding or sticking.

7. A plug assembly for a high-pressure valve forming part of a common rail injection circuit of an internal combustion engine, the valve being of the type with a tubular body extending along a longitudinal axis and in which, under the action of a piloted actuator, a needle moves longitudinally between a closed position and an open position, the plug assembly comprising:

a plug having a flat part able to be fixed onto the tubular body transversally to the longitudinal axis, and

a spring applying a force to the needle to bias the needle axially towards the closed position,

wherein the spring is fixed to the plug forming with it an integrated assembly, and

wherein the plug is provided with a tubular jacket extending axially from the circumference of the flat part to a distal end, the plug being able to be fixed to the tubular body at the distal end so that the plug defines an internal space which houses and guides a movable part of the piloted actuator.

8. A process for assembly of a high-pressure valve of a common rail injection circuit of an internal combustion engine, the process comprising the following steps:

providing a tubular body extending along a longitudinal axis, a passage being formed at one end of the tubular body,

providing a needle and a piloted actuator,

providing a plug having a flat part able to be fixed onto the tubular body transversally to the axis of the tubular body, the plug being provided with a bearing to guide the needle along the longitudinal axis,

providing a spring,

arranging the needle and the piloted actuator in the tubular body,

fixing the spring to the plug so as to form an integrated plug assembly,

arranging the plug assembly so that the spring applies a force to the needle,

fixing the plug assembly to the tubular body.

9. A process for assembly of a high-pressure valve as described in claim 8 in which the plug includes an annular protuberance which extends axially from the flat part, wherein the step of fixing the spring to the plug includes fixing the spring to the annular protuberance.

10. A process for assembly of a high-pressure valve as described in claim 9 in which the spring is of the helical type and in which the annular protuberance includes a jamming section having an external diameter which is slightly greater than an internal diameter of the spring, wherein the step of fixing the spring to the annular protuberance includes jamming a turn_of the spring around the jamming section.

11. A high-pressure valve forming part of a common rail injection circuit of an internal combustion engine, the valve comprising:

a tubular body extending along a longitudinal axis and having, a passage for the fuel being formed at a first end of the tubular body,

a needle arranged axially in the tubular body and being displaced under the action of a piloted actuator between an open position of the passage and a closed position of the passage, and

a plug assembly fixed to a second end of the tubular body opposite to the first end, the plug assembly comprising:

a plug having a flat part fixed onto the tubular body transversally to the longitudinal axis, and

a spring applying a force to the needle to bias the needle axially towards the closed position,

wherein the spring is fixed to the plug forming with it an integrated assembly, and

wherein the plug includes an annular protuberance which extends axially from the flat part so as to form a bearing for guiding the needle longitudinally, the spring being fixed onto the annular protuberance.

12. A high-pressure valve as described in claim 11 in which the spring is of the helical type and in which the annular protuberance includes a jamming section having an external diameter which is slightly greater than an internal diameter of the spring so that the spring is fixed by jamming of a turn of the spring around the jamming section.

13. A high-pressure valve as described in claim 12 in which the jamming section is arranged at a base of the annular protuberance close to the flat part of the plug, the annular protuberance including a guiding section which extends beyond the jamming section and the external diameter of which is less than the internal diameter of the spring so as to act, during assembly, as a guide for the spring without hampering the movements of the spring during compression and expansion phases.

14. A high-pressure valve as described in claim 13 in which the guiding section and the jamming section are joined by a surface in the form of a truncated cone.

15. A plug assembly as described in claim 11 in which the annular protuberance is formed in one piece with the plug.

16. A plug assembly as described claim 11 in which the spring is fixed to the plug by welding or sticking.

17. A high-pressure valve forming part of a common rail injection circuit of an internal combustion engine, the valve comprising:

a tubular body extending along a longitudinal axis and having, a passage for the fuel being formed at a first end of the tubular body,

a needle arranged axially in the tubular body and being displaced under the action of a piloted actuator between an open position of the passage and a closed position of the passage, and

a plug assembly fixed to a second end of the tubular body opposite to the first end, the plug assembly comprising:

a plug having a flat part fixed onto the tubular body transversally to the longitudinal axis, and

a spring applying a force to the needle to bias the needle axially towards the closed position,

wherein the spring is fixed to the plug forming with it an integrated assembly, and

wherein the plug is provided with a tubular jacket extending axially from a the circumference of the flat part to a distal end, the plug being able to be fixed to the tubular body at the distal end so that the plug defines an internal space which houses and guides a movable part of the piloted actuator.