DE102007048752A1 - Fuel i.e. petroleum product, filling level detection device for installing in e.g. manhole pit of fuel tank of filling station, has indicator magnet displacing guide relative to wire in way different from intended movement of lifting body - Google Patents

Abstract

The device (1) has a filling level magnet whose position along a measuring wire (8) is detected by an operating electronic circuit (10) of a magnetostrictive position measuring system, and an indicator magnet. The position of the indicator magnet along the measuring wire is detected by the operating electronic circuit. The indicator magnet displaces a guide (2) relative to the measuring wire in a way different from the intended movement of a lifting body (4) during upward movement. The filling level magnet and the indicator magnet are identical to each other.

Description

The The invention relates to a level detection device with a magnetostrictive position measuring system whose mounting in the correct position can be monitored, in particular in the sense of an uninstall safeguard.

The magnetostrictive position measurement is a known technique (see eg. US 3,189,849 and US 3,225,312 ) and is used because of its advantages for position measuring tasks in mechanical engineering and in level measurement.

at a magnetostrictive measuring system is a permanent magnet as Positioners used. Due to the magnetostriction effect in a magnetic waveguide, hereinafter referred to as measuring wire, Ultrasonic waves generated. The duration of these ultrasonic waves can by means of an operating electronics with high precision be measured so that the position of the permanent magnet z. B. can be determined exactly reproducible to 2 microns. It is also possible to have a larger number of such magnetic positioners on a magnetostrictive Measuring wire simultaneously or virtually simultaneously, which exploited in conventional level and interface measuring systems becomes.

in principle it is for the reliability of the readings of Sensors of vital importance that the sensors in one correct position are installed. For example, the reading is a tank content measurement depends on the sensor in the tank container led to the ground is, because otherwise one affecting the accuracy Shift into the measured value is received. Therefore, a control option desirable, indicating that the sensor is down to the bottom of the tank was installed.

A similar Problem arises for tank content measurements in the custody account Traffic, eg. B. with regard to mineral oil products in one Tanker. The quantities delivered by the tanker are over determines a tank content measurement. When the level measuring device is not in the correct position, this also results in a Incorrect measurement.

A Another application in which the control of the installation position of a Sensors is essential, is the monitoring of Domschächten at service stations to liquid ingress with the help of a Level measurement. There are two typical error cases here. The most common case is that z. B. by heavy rain water enters the shaft. Since this water is disturbing, it must be detected by the level measurement and then pumped out become. Another case can occur when the fuel is out the tank is conveyed by means of a pressure pump to the dispensers. If at the fuel lines in the area of the dome shaft of the Tanks experience a leak, fuel can leak out and the shaft to fill. This dangerous fault (risk of explosion and pollution) must be recognized immediately, so that the associated Fuel pump can be switched off. But since the safer Case of water ingress will result in an alarm the monitoring system by the operator of the gas station frequently Overridden (manipulated) by the level sensor pulled up in a holder so that it does not dip.

Around to detect and report such manipulation, there are Prior art level detection devices with a magnetostrictive position measuring system, in which a displacement mechanism moves an additional magnet whose position is from the magnetostrictive position measuring system is detected. such Devices are relatively expensive.

It Object of the invention, a level detection device to provide with a magnetostrictive position measuring system whose assembly monitored in the correct position with little additional effort can be.

These Task is solved by a level detection device with the features of claim 1. Advantageous embodiments The invention will become apparent from the dependent claims.

The Inventive level detection device contains a magnetostrictive position measuring system. there has one movable along a guide and for swimming at a boundary between two fluids arranged buoyant body a magnet, which in the following "level magnet" is called. The position of the level magnet along a measuring wire is by means of an operating electronics of the magnetostrictive position measuring system detectable. So far, the structure of the level detection device corresponds a conventional magnetostrictive position measuring system.

According to the invention, a magnet is provided, hereinafter referred to as "indicator magnet", whose position along the measuring wire can be detected by means of the operating electronics of the magnetostrictive position measuring system and which is adapted to move relatively when the guide is displaced (eg during an upward movement of the guide) to shift to the measuring wire in a manner different from a proper movement of the buoyant body. That is, if the leadership z. B. pulled up in manipulative intent is, the indicator magnet moves relative to the measuring wire, preferably in a range which is not covered in the intended use of the level detection device of the level magnet. In the measurement data evaluation of the magnetostrictive position measuring system in the operating electronics or an associated computer thus results in a signal indicating that the level detection device is no longer in the correct position. With the help of this signal, an alarm can be triggered, z. B. in optical or acoustic form. Furthermore, the signal can be logged.

The Device according to the invention is as a level detection device designated. It can be set up as a measuring device, for. B. to perform tank content measurements, but also as a pure monitoring device, which detects when a level exceeds a predetermined level, without it being on a reading for the level arrives.

Of the Float floats with the level magnet at a boundary between two fluids, e.g. B. at a border between Water and air or fuel and air. It can too be provided several buoyancy bodies, each on drive body having a level magnet, for. B. a buoyancy body for a boundary layer between water and oil or Fuel and a buoyant body for a boundary layer between oil or fuel and air. A magnetostrictive Position measuring system is able to adjust the positions of several buoyancy bodies to capture.

at a preferred embodiment of the invention is the Level magnet identical to the indicator magnet. there may be a bearing body movable along the guide be provided, the intended installation the level detection device on a predetermined outer Pad rests and the buoyant body above his deepest and detectable by the magnetostrictive Postionsmesssystem Holding position. When the leadership of the level detection device pulled up, makes the bearing body this movement initially not with, as he continues on the outside Pad rests, so that it relative to the measuring wire after moved down. If the buoyancy body for lack of fluid he does not experience sufficient buoyancy in contact with the bearing body and moves relatively to the measuring wire also down, so that in a position which, during normal operation of the Level detection device can not be achieved. This condition may be due to the magnetostrictive position measurement system easily detected and then evaluated as an alarm condition. If the buoyancy body at the beginning of the upward movement the guide floats in a liquid will the alarm state is reached only when advanced Upward movement of the bearing body in one after moved down position z. B. on a stop on the guide is applied and pulled up with the guide, until he touches the buoyant body, then himself also located in a lower position relative to the measuring wire, than the intended use of the level detection device equivalent.

at This configuration is therefore not an additional magnet required, but the level magnet can simultaneously be used as an indicator magnet. The bearing body is a simple component that can be produced inexpensively leaves.

at the above-explained operation is the bearing body separate from the float and is by a sufficiently high mass secured against floating. But it is also conceivable, the bearing body to integrate with the float to form a structural unit. In this Case, the bearing body is only on the predetermined outer Pad on when the buoyancy body is not due to lack of fluid floats. But at the latest, if at an upward movement the leadership of the buoyancy body with bearing body enters the lower area of the guide is located the indicator magnet relative to the measuring wire also outside of possible under normal use Movement range of the level magnet / indicator magnet.

at another advantageous embodiment of the invention is the Indicator magnet different from the level magnet and arranged on a stationary support. Such a holder can z. B. for holding the level detection device be furnished and z. B. in the upper part of the guide attack the level detection device. The indicator magnet is then located in an area of the intended Movement range of the fill level magnet in the buoyancy body differs. The magnetostrictive position measuring system can do this easily to capture. Now, if the guide is moved up, remains the indicator magnet on the stationary mount, so moves relative to down the measuring wire. This can be over the magnetostrictive Position measuring system to trigger a signal, z. B. a Alarm.

at A variant of this embodiment is the indicator magnet arranged in a holder that does not simultaneously guide the level detection device holds. To this Purpose of the indicator magnet z. B. in a screw-in introduced, which screw into such a separate holder leaves.

at preferred embodiments of the invention has the leadership a tube on, with the measuring wire inside the tube and can be aligned along the tube. This tube is preferably sealed against external media.

The Guide and the buoyant body can of be surrounded by a housing, the z. B. designed like a tube is. The housing protects the buoyant body against external influences. With it liquid can get to the buoyant body, the housing preferably provided with openings.

ever after use, the inventive Level detection device also more than a buoyancy body having fill level magnet, as already explained.

The Inventive level detection device So opens up the possibility of using simple means and reliably recognize without much effort if the leadership z. B. in manipulative intent their desired position is moved (eg upwards), so that if necessary an alarm can be triggered.

in the The invention will be described below with reference to exemplary embodiments further described. The drawings show in

1 a schematic longitudinal section through a first embodiment of a level detection device according to the invention and

2 a schematic longitudinal section through a second embodiment of a level detection device according to the invention.

In 1 is an embodiment of a level detection device 1 shown in a schematic longitudinal section. The level detection device 1 can z. B. in the dome shaft of a fuel tank of a gas station or in a sump under a fuel pump be mounted to detect when a liquid in its environment exceeds a predetermined level. In this case, an alarm signal should be issued.

The level detection device 1 has a guide 2 in the form of a cylindrical tube with a closed lower end side. On the lead 2 is a buoyant body 4 movable up and down. The mass and volume of the buoyant body are coordinated so that the buoyancy body 4 floating on a fuel level.

In an interior of the buoyancy body 4 there is a permanent magnet 6 , The position of the magnet 6 along the guide 2 can be detected with the help of a magnetostrictive position measuring system, the one in the interior of the guide 2 arranged measuring wire and a back wire 9 having. The measuring wire 8th and the back wire 9 are with an operating electronics 10 connected.

The operating electronics 10 Located in a housing part, which merges down into a tubular housing, which is the guide 2 and the buoyancy body 4 surrounds. At its lower end 14 stands the housing 12 open.

Below the buoyancy body 4 is a bearing body as an independent component 16 arranged along the guide 2 is displaceable. The bearing body 16 is so heavy that it does not float when passing through openings in the wall of the housing 12 in the interior of the case 12 arrives. In the intended use of the level detection device 1 stands the lower end 14 of the housing 12 on an external surface 18 on, z. B. a bottom part of the dome shaft or the bottom of the sump of a fuel pump. This is the condition in which the bearing body 16 in 1 drawn in solid lines. This is the lowest position of the buoyancy body 4 specified for the intended operation, which also in 1 drawn in solid lines. When accessing liquid, the buoyant body moves 4 up; he usually can not take a lower position.

Now, if the level detection device 1 z. B. is moved upward in manipulative intention, the bearing body remains 16 because of the open end of the housing 12 on the pad 18 stand. That is, relative to the leadership 2 and the measuring wire 8th shifts the bearing body 16 downward. Because the bearing body 16 the buoyancy body 4 supports, also shifts the buoyant body 4 with the magnet 6 relative to the measuring wire 8th down, what of the operating electronics 10 of the magnetostrictive position measuring system is detected. In this case, z. B. an alarm signal can be specified. In 1 are the relative to the leadership 2 shifted down positions of the buoyancy body 4 and the bearing body 16 drawn in dotted lines.

If the buoyant body 4 floats in a liquid reach the bearing body 16 and the buoyancy body 4 only then her in 1 marked end positions at the bottom of the guide 2 when the level detection device has been moved a little bit higher up. This prevents a in 1 Not marked stop at the bottom 14 of the housing 12 in that the bearing body 16 out of the case 12 fall out.

In 2 another embodiment of a level detection device is shown here with 20 is designated. The level detection device 20 is at a storage tank 21 mounted for a liquid and serves as a level measuring device to increase the amount of stored in the storage tank 21 to be able to determine the liquid.

The level detection device 20 has a tubular guide 22 on, along which is a buoyant body 24 can move up and down. The buoyancy body 24 Floats at a level 25 the liquid. In its interior is a level magnet 26 arranged.

Within the leadership 22 extend a measuring wire 28 and a back wire 29 leading to an operating electronics 30 are guided. As a result, in turn, a magnetostrictive position measuring system is formed, with which the height of the level 25 can be measured with high accuracy.

To obtain accurate readings, it is necessary that the guide tube 22 is mounted at the correct height. To prevent the level detection device 20 is moved improperly, especially upwards, is located in an external bracket 32 for the leadership 22 another permanent magnet, namely the indicator magnet 34 , The holder 32 is with the storage tank 21 connected. The correct position of the indicator magnet 34 in relation to the measuring wire 28 is determined and stored by a measurement with the magnetostrictive position measuring system. When the level detection device 20 is shifted, changes the actual position of the indicator magnet 34 in terms of leadership 22 , which is noticeable by comparison with the stored nominal value and can be displayed, for. B. as an optical or acoustic signal.

In the embodiment according to 2 is the indicator magnet 34 on the bracket 32 arranged, which is part of the storage tank 21 is. In other embodiments, a separate holder may be used for an indicator magnet that is in favorable geometry to the measuring wire 28 is mounted so that it does not move with a displacement of the level detection device. A favorable position for the indicator magnet can also be located, for example, in the lower region of the measuring arrangement.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 3189849 [0002]
• US 3225312 [0002]

Claims (11)

Level detection device with a magnetostrictive position measuring system, wherein one along a guide ( 2 ; 22 ) movable and swimming at a border ( 25 ) between two fluids arranged buoyant body ( 4 ; 24 ) a magnet ( 6 ; 26 ), the level magnet, whose position along a measuring wire ( 8th ; 28 ) by means of an operating electronics ( 10 ; 30 ) of the magnetostrictive position measuring system, characterized by a magnet ( 6 ; 34 ), the indicator magnet, whose position along the measuring wire ( 8th ; 28 ) by means of the operating electronics ( 10 ; 30 ) of the magnetostrictive position measuring system and which is adapted to move during a displacement, in particular an upward movement, of the guide ( 2 ; 22 ) relative to the measuring wire ( 8th ; 28 ) in one of an intended movement of the buoyant body ( 4 ; 24 ) differentiable way to relocate. Level detection device according to claim 1, characterized in that the level magnet ( 6 ) with the indicator magnet ( 6 ) is identical. Level detection device according to claim 2, characterized by a longitudinal guide ( 2 ) movable bearing body ( 16 ), which, when properly installed, the level detection device ( 1 ) on a given outer surface ( 18 ) rests and the buoyancy body ( 4 ) above its deepest and detectable position by the magnetostrictive position measuring system. Level detection device according to claim 3, characterized in that the bearing body with the Buoyancy is integrated into a unit. Level detection device according to claim 3, characterized in that the bearing body ( 16 ) separately from the buoyant body ( 4 ) and is secured by a sufficiently high mass against floating. Level detection device according to claim 1, characterized in that the indicator magnet ( 34 ) of the fill level magnet ( 26 ) is different and on a stationary bracket ( 32 ) is arranged. Level detection device according to claim 6, characterized in that the holder ( 32 ) for holding the level detection device ( 20 ) and preferably at the top of the guide ( 22 ) at the level detection device ( 20 ) attacks. Level detection device according to one of claims 1 to 7, characterized in that the guide ( 2 ; 22 ) has a tube. Level detection device according to claim 8, characterized in that the measuring wire ( 8th ; 28 ) inside the tube ( 2 ; 22 ) and along the tube ( 2 ; 22 ) is aligned. Level detection device according to one of claims 1 to 9, characterized in that the guide ( 2 ) and the buoyancy body ( 4 ) of a housing ( 12 ) are surrounded, which is preferably designed like a tube. Level detection device according to one of Claims 1 to 10, characterized in that more than a buoyant body is provided, each buoyant body having a level magnet.