A sensor element ( 30 ) measures a Hall voltage generated by a movable magnet ( 16 ). For this purpose, the sensor element ( 30 ) comprises a ceramic base element ( 40 ) which has connected therewith a detector element ( 46 ). The detector element ( 46 ) is protected with the aid of a cover element ( 42 ) against an aggressive environment produced by fuel or fuel vapors in a fuel tank ( 34 ) of a motor vehicle. The detector element ( 46 ) has connected therewith electric conductors ( 60 ) which are routed through the cover element ( 42 ) and/or the base element ( 40 ) for connecting the detector element ( 46 ) with a voltage source and/or an evaluation unit. The cover element ( 42 ) and possibly the base element ( 40 ) reliably encapsulate the detector element ( 46 ) against the aggressive environment such that by simple constructive measures the service life of the sensor element ( 30 ) is increased.
1. A contactlessly operating level indicator for a fuel tank in a motor vehicle, comprising:
(a) a rotatably supported lever connected with a float and a magnet; and
(b) a sensor element for measuring a magnetic field generated by a movable magnet, comprising
i. a base element made from an electrically insulating material;
ii. a detector element connected with the base element;
iii. a metal cover element connected with the base element at a distance to the detector element; and
iv. electric conductors connected with the detector element and routed through the cover element, or the base element, or the cover element and the base element, for connection with a voltage source, or an evaluation unit, or the voltage source and the evaluation unit,
wherein the magnet connected with the lever is arranged between the sensor element and a rotary axis of the lever such that, as a function of the position of the float, the magnetic field measured by the sensor element is changed, and wherein the fuel tank comprises a receiving opening for receiving the sensor element or an intermediate piece, the sensor element being guided through the receiving opening such that the detector element is arranged inside the fuel tank and conductor ends of the electric conductors are arranged outside the fuel tank.
2. The level indicator according to claim 1 , wherein an intermediate piece has rotatably connected therewith the lever and has an opening, wherein the sensor element is arranged in the opening of the intermediate piece such that the detector element is associated with a side of the intermediate piece facing the lever, and a projection of the sensor element bears, in the form of a stopper, on the side of the intermediate piece facing away from the lever.
3. The level indicator according to claim 1 , wherein the detector element comprises one or more components selected from the group consisting of a Hall effect sensor, an AMR sensor and a GMR sensor.
4. The level indicator according to claim 1 , wherein a cover capsule comprises the cover element connected with a lid.
5. The level indicator according to claim 1 , wherein the base element is completely arranged inside the cover element.
6. The level indicator according to claim 5 , wherein the projection forms a concave right angle together with the outside facing away from the detector element.
7. The level indicator according to claim 1 , wherein the cover element, or the base element, or the cover element and the base element, comprise a projection configured as a shoulder that extends away from the detector element and is provided around a circumference for limiting insertion depth of the cover element in an opening.
8. The level indicator according to claim 1 , wherein at least one of the electric conductors is configured as a conductor conduit arranged in the base element.
9. The level indicator according to claim 1 , wherein the cover element comprises at least one contact element for conducting electric current.
10. A contactlessly operating level indicator for a fuel tank in a motor vehicle, comprising:
(a) a rotatably supported lever connected with a float and a magnet; and
(b) a sensor element for measuring a magnetic field generated by a movable magnet, comprising
i. a base element made from an electrically insulating material;
ii. a detector element connected with the base element;
iii. a metal cover element connected with the base element at a distance to the detector element; and
iv. electric conductors connected with the detector element and routed through the cover element, or the base element, or the cover element and the base element, for connection with a voltage source, or an evaluation unit, or the voltage source and the evaluation unit,
wherein the magnet connected with the lever is arranged between the sensor element and a rotary axis of the lever such that, as a function of the position of the float, the magnetic field measured by the sensor element is changed, wherein an intermediate piece has rotatably connected therewith the lever and has an opening, wherein the sensor element is arranged in the opening of the intermediate piece such that the detector element is associated with a side of the intermediate piece facing the lever, and a projection of the sensor element bears, in the form of a stopper, on the side of the intermediate piece facing away from the lever.