Sensor for a high-pressure line, and method for producing same

1. A sensor for a high-pressure line comprising:

an outer tube of metal with an outer surface, an inner surface, an outer diameter and an inner diameter, and an inner tube of metal with an outer surface, an inner surface, an outer diameter and an inner diameter, wherein the inner tube extends concentrically in the outer tube such that the inner tube and the outer tube together form a tube, and wherein the overall wall thickness measured as half of the difference between the outer diameter of the outer tube and the inner diameter of the inner tube is equal to or larger than the inner diameter of the inner tube;

at least one groove extending in a longitudinal direction of the tube in the inner surface of the outer tube or in the outer surface of the inner tube;

at least one signal line placed in the groove; and

at least one pick-up element connected to the signal line,

wherein the pick-up element is placed at least in the groove or in at least one recess provided in addition to the groove at least in the outer surface of the inner tube or in the inner surface of the outer tube,

wherein the outer tube is in a frictional connection with the inner tube, and

wherein the inner tube is a strain-hardened tube with a tensile strength of 900 N or more.

2. The sensor according to claim 1 , wherein the sensor is a pressure sensor, and wherein the at least one pick-up element is a force pick-up element being in engagement with the inner tube such that the force pick-up element during operation of the sensor measures a force applied to the inner tube.

3. The sensor according to claim 1 , wherein the sensor comprises three grooves extending in a longitudinal direction of the tube at least in the inner surface of the outer tube or in the outer surface of the inner tube,

wherein in each of the three grooves at least one signal line is placed,

wherein at least in each of the three grooves or in three recesses each abutting one of the three grooves a pick-up element connected to at least one signal line is placed, and

wherein the pick-up elements in the longitudinal direction of the tube are located such there is a cross-sectional plane perpendicular to the longitudinal direction of the tube, which is intersecting all three pick-up elements.

4. The sensor according to claim 3 , wherein the three pick-up elements are spaced from each other by 120° in the circumferential direction of the tube.

5. The sensor according to claim 3 , wherein the three pick-up elements are force pick-up elements, such that the sensor is a pressure sensor.

6. The sensor according to claim 5 , wherein the sensor in addition comprises a thermometer, wherein the thermometer is placed at least in a groove or in a recess placed at least in the outer surface of the inner tube or in the inner surface of the outer tube.

7. The sensor according to claim 1 , wherein the inner tube has a larger elongation than the outer tube.

8. The sensor according to claim 1 , wherein the overall wall thickness amounts to at least 3 mm.

9. A sensor for a high-pressure line comprising:

an outer tube of metal with an outer surface, an inner surface, an outer diameter and an inner diameter, and an inner tube of metal with an outer surface, an inner surface, an outer diameter and an inner diameter, wherein the inner tube extends concentrically in the outer tube such that the inner tube and the outer tube together form a tube, and wherein the overall wall thickness measured as half of the difference between the outer diameter of the outer tube and the inner diameter of the inner tube is equal to or larger than the inner diameter of the inner tube;

at least one groove extending in a longitudinal direction of the tube in the inner surface of the outer tube or in the outer surface of the inner tube;

at least one signal line placed in the groove; and

at least one pick-up element connected to the signal line,

wherein the pick-up element is placed at least in the groove or in at least one recess provided in addition to the groove at least in the outer surface of the inner tube or in the inner surface of the outer tube,

wherein the outer tube is in a frictional connection with the inner tube, and

wherein the inner tube has a larger elongation than the outer tube.

10. The sensor according to claim 9 , wherein the sensor is a pressure sensor, and wherein the at least one pick-up element is a force pick-up element being in engagement with the inner tube such that the force pick-up element during operation of the sensor measures a force applied to the inner tube.

11. The sensor according to claim 9 , wherein the sensor comprises three grooves extending in a longitudinal direction of the tube at least in the inner surface of the outer tube or in the outer surface of the inner tube,

wherein in each of the three grooves at least one signal line is placed,

wherein at least in each of the three grooves or in three recesses each abutting one of the three grooves a pick-up element connected to at least one signal line is placed, and

wherein the pick-up elements in the longitudinal direction of the tube are located such there is a cross-sectional plane perpendicular to the longitudinal direction of the tube, which is intersecting all three pick-up elements.

12. The sensor according to claim 11 , wherein the three pick-up elements are spaced from each other by 120° in the circumferential direction of the tube.

13. The sensor according to claim 11 , wherein the three pick-up elements are force pick-up elements, such that the sensor is a pressure sensor.

14. The sensor according to claim 13 , wherein the sensor in addition comprises a thermometer, wherein the thermometer is placed at least in a groove or in a recess placed at least in the outer surface of the inner tube or in the inner surface of the outer tube.

15. The sensor according to claim 9 , wherein the overall wall thickness amounts to at least 3 mm.

16. A method for manufacturing a sensor for a high-pressure line comprising the steps:

providing an outer tube of metal with an outer surface, an inner surface, an outer diameter and an inner diameter;

providing an inner tube of metal with an outer surface, an inner surface, an outer diameter and an inner diameter, wherein the outer diameter of the inner tube is smaller than the inner diameter of the outer tube, and wherein the overall wall thickness measured as a half of a difference between the outer diameter of the outer tube and the inner diameter of the inner tube is equal to or larger than the inner diameter of the inner tube;

providing at least one groove extending in a longitudinal direction of the outer tube or of the inner tube into at least the inner surface of the outer tube or into the outer surface of the inner tube;

placing at least one signal line in the groove;

placing at least one pick-up element connected to the signal line at least in the groove or in at least one recess provided at least in the outer surface of the inner tube or in the inner surface of the outer tube;

inserting the inner tube into the outer tube such that the inner tube extends in the outer tube; and

drawing the inner tube and the outer tube together through a first drawing die having an inner tool surface forming the outer surface of the outer tube,

wherein a tool diameter of the inner tool surface of the first drawing die is selected such that the by drawing the inner diameter of the outer tube is reduced such that after the drawing the outer tube is in frictional connection with the inner tube.

17. The method according to claim 16 , wherein by the drawing of the inner tube and the outer tube together through the first drawing die a wall thickness of the outer tube and the inner diameter of the outer tube are reduced such that the outer diameter of the inner tube is reduced by at least 0.01 mm and by at most 0.3 mm.

18. The method according to claim 17 , wherein by the drawing of the inner tube and the outer tube together through the first drawing die the inner diameter of the inner tube is not reduced.

19. The method according to claim 16 , wherein providing the inner tube and providing the groove in the outer surface of the inner tube comprises the steps:

providing a hollow of metal; and

drawing the hollow through a second drawing die with an inner tool surface forming the outer surface of the inner tube into inner tube,

wherein an inner tool diameter of the inner tool surface of the second drawing die is selected such that the outer diameter of the inner tube is smaller than the inner diameter of the outer tube, and

wherein the inner tool surface of the second drawing die comprises at least one section projecting inwardly such that the at least one groove extending in a longitudinal direction of the inner tube is drawn into the outer surface of the inner tube.

20. The method according to claim 19 , wherein the inner tool surface of the second drawing die comprises a plurality of sections projecting inwardly, such that a plurality of grooves is drawn into the outer surface of the inner tube in a longitudinal direction.

21. The method according to claim 16 , wherein, prior to the step of inserting the inner tube into the outer tube, at least the inner tube is worked by chip forming machining, such that at least one recess is formed in the outer surface of the inner tube, and wherein the recess adjoins at least one groove.