Radar Level Gauge Comprising a Safety Device

Abstract

The invention is a radar level gauge comprising a signal generator for generating electromagnetic waves and an antenna for emitting the electromagnetic waves in a container and for receiving electromagnetic waves reflected by the container. The radar level gauge also comprises a safety device for verifying the functional capability or for improving the measuring quality of the radar level gauge, said safety device having a reflector and an adjustment device and/or a reduction device and being suitably designed to adjust the reflector and/or the reduction device at least between a first position and a second position, in which the reflector reflects the electromagnetic waves in a reduced manner. The adjustment device acts on the reflector and/or the reduction device in a contactless manner.

Claims

1. A radar level gauge comprising a signal generator for generating electromagnetic waves and an antenna for emitting the electromagnetic waves as well as receiving reflected electromagnetic waves, comprising a safety device for checking the functionality or for improving the quality of measurements of the radar level gauge, with the safety device comprising a reflector and an adjustment device and a reduction device and being suitably embodied to adjust the reflector and the reduction device at least between a first position, in which the reflector reflects the electromagnetic waves, and a second position, in which the reflector reflects the electromagnetic waves in a reduced fashion, wherein the adjustment device acts in a touchless fashion upon the reflector and the reduction device.

2. The radar level gauge according to claim 1, wherein the adjustment device comprises a magnetic coupling to the reflector and/or the reduction device.

3. The radar level gauge according to claim 1, wherein the adjustment device rotationally moves the reflector and the reduction device.

4. The radar level gauge according to claim 1, wherein the adjustment device acts linearly upon the reflector and the reduction device.

5. The radar level gauge according to claim 1, wherein the adjustment device comprises a permanent magnet.

6. The radar level gauge according to claim 1, wherein the adjustment device is arranged in a housing separated from the measuring environment in a preferably pressure-tight fashion.

7. The radar level gauge according to claim 6, wherein the housing is welded to a fastening flange.

8. The radar level gauge according to claim 6, wherein the adjustment device is arranged inside the housing and the reflector or the reduction unit outside thereof.

9. The radar level gauge according to claim 1, wherein the safety arrangement is embodied such that it automatically shifts into the second position without any operational intervention.

10. The radar level gauge according to claim 1, wherein the adjustment device, the reflector or the reduction device comprise a permanent magnet.

11. The radar level gauge according to claim 1, wherein the reduction device is embodied as a sheath that is mobile in reference to the reflector.

12. The radar level gauge according to claim 11, wherein the sheath of the reflector projects beyond the reflector in the second position and in the radial direction.

13. The radar level gauge according to claim 12, wherein the reflector is embodied as a stop for the reduction device.

14. The radar level gauge according to claim 13, wherein the reduction device is embodied such that in the second position it reflects the electromagnetic waves away from the antenna.

15. The radar level gauge according to claim 1, wherein the arrangement comprises a sensor for monitoring the position of the reflector and the reduction device.

16. The radar level gauge according to claim 1, wherein the adjustment device is driven automatically.

17. The radar level gauge according to claim 1, wherein the adjustment device is coupled to a field device.

18. A safety device for the radar level gauge of claim 1, comprising a reflector and an adjustment device and a reduction device and being suitably embodied to adjust the reflector and the reduction device at least between a first position, in which the reflector reflects the electromagnetic waves, and a second position, in which the reflector reflects the electromagnetic waves in a reduced fashion, wherein the adjustment device acts in a touchless fashion upon the reflector and the reduction device.

Description

[0024] In the following the present invention is explained in greater detail with reference to the attached figures.

[0025] The figures show:

[0026] FIG. 1 a sketch of the principle of a radar level gauge comprising a safety device in the first position, and

[0027] FIG. 2 the radar level gauge of FIG. 1 with a safety device in the second position.

[0028] FIG. 3 shows another exemplary embodiment of a radar level gauge with a safety device showing a rotary reflector in the first position,

[0029] FIG. 4 the radar level gauge of FIG. 3 in a second position,

[0030] FIG. 5 a radar level gauge with a rotationally embodied reduction device in the first position, and

[0031] FIG. 6 the radar level gauge of FIG. 5 in the second position.

[0032] FIG. 1 shows a schematic illustration of a radar level gauge 1 with a safety device 5, with the safety device 5 being shown in a first position I, in which a reflector 7 of the safety device 5 shows electromagnetic waves emitted by an antenna 3 of the radar level gauge 1 in a reflected fashion. The radar level gauge 1 is designed in the present exemplary embodiment with an antenna 3, which in the present case is embodied as a horn antenna. However, other forms of antennas are possible here, too, without leaving the scope of the present invention.

[0033] In the present exemplary embodiment the safety device 5 is designed as a cylindrically formed housing 10, with at the end near the container of reflector 7 being arranged in an alignment perpendicular to a primary direction of emission A of the antenna 3. The housing 10 is arranged parallel in reference to the radar level gauge 1 in a fastening flange 6 and this way already aligned by the factory and matches the fill level gauge 1. The safety device 5 further comprises a reduction device 15, which is embodied as a sheath displaceable axially at the housing. At one end of the reduction device 15 near the flange the device comprises two permanent magnets 12, which cooperate with two other permanent magnets 12 arranged at an adjustment device 9 provided in the housing 10. In order to yield higher protection from malfunction of the arrangement, here additional magnets may be arranged distributed over the entire length.

[0034] By a magnetic coupling between the permanent magnet 12 at the reduction unit 15 and the adjustment device 9 it is possible to lift the reduction device 15, embodied as a sheath, opposite the forces of gravity from the reflector 7, arranged with its end at the housing 10, which reflector in the present case also serves as a stop, and expose it as shown in FIG. 1 for reflecting electromagnetic waves emitted by the antenna 3. The housing 10 can in this embodiment be connected circumferentially with the fastening flange 6, for example welded, so that an arrangement develops which is pressure and diffusion tight. This way a radar level gauge 1 with a safety device 5 shown in FIG. 1 can also be used for toxic and/or pressurized media.

[0035] In order to allow a magnetic coupling through the housing 10 it is necessary that it is at least sectionally made from a non-magnetic material, for example stainless steel.

[0036] An activation of the adjustment device 9, not shown in greater detail in the present case, can occur manually, pneumatically, or electrically. In particular a manual and pneumatic operation of the adjustment device 9 is preferred because this way a low susceptibility to the adjustment malfunctioning can be achieved in a particularly simple fashion.

[0037] FIG. 2 shows the radar level gauge 1 of FIG. 1 with the safety device 5 in a second position II, in which the reduction device 15 reflects the electromagnetic waves emitted by the antenna 3 to an area oriented parallel in reference to the primary direction of emission A of the antenna 3 and thus guides them in the direction of the filled in goods. When compared to the first position I shown in FIG. 1, here a considerable reduction of the reflection is yielded, causing the safety device 5 to be essentially deactivated. In the position shown in FIG. 2 it is also clearly discernible that the reflector 7 in the present embodiment serves as a stop for the reduction device 15.

[0038] If in the exemplary embodiment shown in FIGS. 1 and 2 the magnetic coupling between the operating device 9 and the reduction device 15 was to operate in an unreliable fashion for whatever reason, additionally the effects of gravity ensure that the reduction device 15 is automatically switched into the second position II and thus a regular operation of the radar level gauge 1 is ensured.

[0039] FIG. 3 shows an exemplary embodiment of a radar level gauge 1 with a safety device 5, with the safety device 5 being in a first position I. The switch from the first position I to the second position II, shown in FIG. 4, occurs in this exemplary embodiment as well via a magnetic coupling, which is realized by two permanent magnets 12, with in this exemplary embodiment the reflector 7 being embodied in a rotary fashion. If in the present exemplary embodiment the adjustment device 9 is rotated in its longitudinal axis, via the permanent magnets 12, which are arranged at one side at the adjustment device 9 and at the other side at a reflector 7, this rotary motion is transferred to the reflector 7 such that it can be moved out of the first position I into the second position II. As further discernible from FIGS. 3 and 4 the reflector 7 is arranged in the first position I such that it reflects electromagnetic radiation emitted by the antenna 3. In the second position II the reflector 7 is removed from the radiation path of the antenna 3 such that no reflection occurs. Similar to the exemplary embodiment shown in FIGS. 1 and 2, it must be emphasized that the housing 10 is connected to the flange 6 in a pressure and diffusion tight fashion and this way the safety device can be applied in an advantageous fashion.

[0040] FIGS. 5 and 6 show another exemplary embodiment of a radar level gauge 1 and in this exemplary embodiment the reduction device 15, as also used in the first exemplary embodiment of FIGS. 1 and 2, is designed asymmetrically and in a rotary fashion. In the first position shown in FIG. 5 the reduction device 15 is arranged such that a portion of the reflector 7 is exposed and this way a reflection of electromagnetic radiation emitted by the antenna 3 can occur. In the second position II, which is shown in FIG. 6, the reduction device 15 is arranged rotated by 180° about its longitudinal axis and completely covers by its asymmetric design the reflector 7 when seen from the antenna 3 such that any electromagnetic radiation emitted by the antenna 3 is further reduced at the reduction device 15, or as shown in FIG. 6, further reflected towards the filled in goods. In any case it is decisive that a signal returned by the reflector 7 in the direction of the antenna 3 is reduced in reference to the first position 1.

[0041] Similar to the previous exemplary embodiment, a coupling between the adjustment device 9 and the safety device 5 occurs, in this case of the reduction device 15, via two permanent magnets 12 arranged at the one side at the adjustment device 9 and at the other side at the reduction device 15. They transfer a rotary motion of the adjustment device 9 to the reduction device 15.

LIST OF REFERENCE CHARACTERS

[0042] 1 radar level gauge [0043] 3 antenna [0044] 4 container [0045] 5 safety device [0046] 6 fastening flange [0047] 7 reflector [0048] 9 adjustment device [0049] 10 housing [0050] 12 permanent magnets [0051] 15 reduction device/sheath [0052] A direction of emission [0053] I first position [0054] II second position