DE102004051148B4 - Level sensor and mounting device for installing the level sensor - Google Patents

Abstract

Level sensor, especially for a fuel tank in a vehicle, having a container-fixed Holding element on which at least two lever encoders for detecting a Levels of a liquid in a container are each arranged pivotally, which lever at least a transmitter for generating an electrical level signal have, by means of a first lever encoder a level of liquid within a first level range is detectable and above the first lever emitter in series with this at least one other, second lever encoder with a second level range for detection a level of fluid is arranged, wherein the individual level ranges at least immediately abut each other, the lever actuators each having a lever with a float, and container side one lower stop each for the lever encoder for determining a lower operating position of The lever sensors each assigned level range (N1, N2) provided characterized in that one with the stops (17, 18) Related assembly device for installing the level sensor in the container through an opening of the container available...

Description

The The invention relates to a level sensor, in particular for one Fuel tank in a vehicle, having a tank-proof Holding element on which at least two lever encoders for detecting a Levels of a liquid in a container are each arranged pivotally, which lift at least have a transmitter for generating an electrical level signal, wherein by means of a first lever emitter, a level of the liquid within a first level range is detectable and above the first lever emitter in series with this at least one other, second lever encoder with a second level range for detection a level of fluid is arranged, wherein the individual level ranges at least immediately abut one another, with the lever actuators each have a lever with a float, and container side one lower stop each for the lever encoder for determining a lower operating position of The levers each associated level range is provided.

The US 2,474,154 shows a level sensor of the type mentioned.

From the EP 1 329 698 A2 a level sensor for a container is known, wherein the lever encoders are fixedly arranged on the inner wall of the container and an installation opening for the level sensor is not present.

From the US 1,757,061 a level sensor is known, which is inserted through an opening in a container in this. The lever of the single lever transmitter can be acted upon by an externally operable slider so that it is pivoted in a vertically downward position.

One the aforementioned level sensor is for a tank known as a liquid level gauge with at the ends of two arms rotatably mounted floats. there becomes a liquid level determined by a plant-external electrical instrument, the the electrical resistance of a potentiometer winding on one Disk measures on which the floats are acted upon. With this Liquid level measuring device should by means of the two floats the level of a moving tank is detected.

Besides that is a device for measuring a level of a liquid in a liquid container with two separate liquid container chambers known. The device has two rotatably mounted levers arranged floats on, wherein in each case one of the floating bodies in one of the liquid container chambers located. This will provide an independent capture of each filling level the liquid in the liquid container chambers allows.

Of Further, for mounting in a fuel tank, a measuring device for one Fuel level in the fuel tank with a float arm device comprising a float known. The measuring device is equipped with a variable resistor and a Regular resistance mounting bracket provided along a support rod at a desired Position can be adjusted to the measuring device for different To be able to use fuel tank depths.

Furthermore is a lever with a float arranged on a very long lever arm for measuring a fuel level in a fuel tank, the a big Height, known. By means of this lever, which due to its considerable Dimensions a large installation space requires, a measurement is over the entire height the fuel tank allows.

task The invention is a level sensor of the type mentioned above, with which a level of the liquid in a big one Area is detectable and also easy to install in the container is.

These Task is inventively characterized solved, that one with the stops Related assembly device for installing the level sensor in the container through an opening of the container is present, with the lever of the other, second lever engageable bottom stop for lifting the lever a downward position in its lower operating position is provided.

Of the level sensor can thus with folded or pivoted lever of the upper lever through an extremely small opening in the container introduced become.

Of the Inventive level sensor is particularly cost-effective in its production and of stable construction. That, for example, rod-shaped, Holding element can, for example, on a lid closing the container be arranged.

By the container side Arrangement of one lower stop for the lever encoder for fixing a lower limit of the levers each associated level range can the Operational safety of the level sensor increase and a high measuring precision to reach.

By using at least two arranged in series lever encoders can ver As a result, the level of liquid in a wide range can be measured. Thus, the invention is particularly advantageous for bulky containers, for example, fuel tanks in trucks suitable. At the same time results in a very compact design of the level sensor, so that only a small opening in the container for installation of the level sensor is sufficient. Such a small opening in the container has the further advantage that only a comparatively small area of the container must be closed after installation of the filling level sensor, for example by means of a lid, and optionally sealed. Since closure and sealing points inherently entail the risk of escaping substances in the container, in particular outgassing fuel, a particularly dense container can be realized with the invention. Due to the compact design of the lever transmitter of the level sensor according to the invention they are largely insensitive to oscillatory excitation, which is constantly present, for example, in vehicles in their operation in the form of vibrations. The vibration insensitivity of the level sensor according to the invention is in particular an advantage compared to the known from the prior art individual lever encoder with a very long lever arm. The large measuring range, which is covered by the level sensor according to the invention, is achieved in that each lever is assigned a separate level range of the liquid. At the same time, the individual level ranges at least directly adjoin one another; for a reliable measurement in any case, for example, even with intensive shaking of the container or very large container tilt, it may be advantageous if the level ranges overlap to a small extent. Starting from such a fundamentally possible overlapping region, the second level range according to the invention is not generally above, but substantially, that is, with a predominant proportion, arranged above the first level range. By providing a plurality of individual level ranges associated with the lever encoder, the level sensor according to the invention has a very high measurement accuracy. In addition, for example, when using the level sensor in a fuel tank, a high resolution can be achieved in a reserve area by means of a corresponding sensor element on the first, lower lever transmitter. To achieve particularly large measuring ranges, correspondingly large container heights, the number of arranged in series lever encoder can be increased beyond two. The installation space required by the invention as a whole for the filling level sensor in the container makes it possible, for example, advantageously to provide additional baffles in the container for calming the liquid, as a result of which the measuring accuracy of the level indicator can be further increased.

you could imagine that the levers, for example, over a Gear arrangement act on a single transmitter. For a simple and compact structure of the level sensor However, it is advantageous if, according to a development of the invention the lever encoders each have a transducer.

According to one Another advantageous embodiment of the invention has a transmitter a lever encoder on a thick-film network (DSN), bringing the manufacturing costs of the level sensor can be kept low.

A Another advantageous embodiment of the invention provides that a transmitter of a lever encoder a magnetic passive Position Sensor (MAPPS), which is an extraordinary high operational reliability and durability can be achieved.

In addition, can also each an upper stop for the lever encoder for fixing an upper limit exist.

A exact positioning of the stops and Assignment to the lever encoders can be advantageously achieved if according to a Development of the invention, the stops arranged on the holding element are.

For example a jamming of the lever in their limit positions can be reliably prevent if according to one Another advantageous embodiment of the invention, the lever of the Lever each with an associated with the respective lever encoder attacks have corresponding stop element.

On Particularly simple way the level sensor can be folded with or pivoted lever encoders through an extremely small opening in the container introduced be when the stop of an installation position in an end position Lever based on the level of the liquid liftable movable and limited in the final position to its top operating position is. The lever emitters are then passed through within the container Lifting by means of the mounting device in its lower operating position brought. It may be possible to raise the lowest Lever dispensed since it regularly during installation in the container through Nudge and pushing up on a container bottom in its lowest operating position, corresponding to a liquid-empty Container, is brought.

Advantageous in particular for use of stops as the level ranges defining stops is when, according to an embodiment of the invention, the stops are arranged on a on the holding element between a lower container installation position and an upper end position vertically slidably guided slider which is fixable in its upper end position.

embodiments The invention are shown schematically in the drawing and will be closer in the following described. Show it:

1 a perspective view of the upper part of a level sensor,

1a the detail "X" off 1 in an enlarged view,

2 a view of the level sensor after 1 with the levers and floats in container installation position,

3 the level sensor after 1 with the levers and floats in their operating position with empty tank,

4 the level sensor after 1 with levers and floats in their transition position from the detection of the lower level range to the upper level range,

5 the level sensor after 1 with levers and floats in their position with fully filled container.

The illustrated level sensor 1 has a tube-like holding element 2 on, at the upper end of an unillustrated flange can be fastened, through which an insertion opening in a fuel tank is closed and the level sensor 1 holds in its installed position.

At the top of the retaining element 2 with a circular cross-section closes over the remainder of the length of the retaining element 2 extending part 3 U-shaped cross section. The opening of the "U" is through a sensor carrier plate 4 closable. The sensor carrier plate 4 is by a latching connection on the holding element 2 fixable.

On the sensor carrier plate 4 are at a distance perpendicular to each other from a first lever 5 and a second lever 6 arranged. Every lever 5 and 6 has a transmitter 7 and 8th , which is a potentiometer-type thick film network 9 . 10 having.

About the thick film network 9 . 10 in each case a grinder is movable, which is attached to a lever 11 . 12 is arranged.

The levers 11 and 12 the transmitter 7 and 8th are in their one end area about pivot axes 13 and 14 freely pivotable on the sensor carrier plate 4 stored. At the other end are the levers 11 and 12 float 15 and 16 arranged to receive a buoyancy corresponding to the level of the liquid in the fuel tank and occupy a position corresponding to this level. Accordingly, a tap on the thick film networks takes place 9 and 10 through the grinders and the generation of a level signal.

Each lever encoder records 5 and 6 its own level range, with the level range (N1) of the first lever emitter 5 substantially below the level range (N2) of the second lever encoder 6 located.

By stops 17 and 18 to which the levers 11 and 12 is the lowest position in which the levers 11 and 12 can pivot.

The attacks 17 and 18 are on a slider 19 arranged at a distance from each other. The slider 19 is inside the retaining element 2 slidably guided in its longitudinal extent between an upper and a lower end position.

The slider has this 19 a hook at its upper end 20 coming out of a window 21 of the holding element 2 protrudes outwards and to move the slider 19 manually acted upon.

At the upper end portion has the slider 19 furthermore protruding transversely to its longitudinal extension approaches 22 in the upper end position of the slider 19 hook 23 of the holding element 2 reach behind and thus prevent a shift towards the lower end position.

The hook 23 are opposite to the lower end of the retaining element 2 Ramps 24 on the holding element 2 trained over which the approaches 22 under elastic deflection of the upper end portion of the slider 19 slide, then into the openings of the hook 23 to be able to engage from above.

To lock the slider 19 in its upper end position, the upper end of the slider 19 from a spring cam 25 of the holding element 2 overlapped.

The attacks 17 and 18 protrude transversely to the longitudinal extent of the holding element 2 by lowering right slots 26 in the sensor carrier plate 4 outward in the swivel range of the lever 11 and 12 ,

Is the slider 19 out of the hook 23 disengaged and in the window 21 moved down until the stops 17 and 18 at the bottom of the slots 26 in conditioning, the levers can 11 and 12 to pivot in an approximately vertical downward position ( 2 ). As a result, the level sensor takes 1 such a slim dimension that it can be easily inserted through a small diameter insertion hole in the fuel tank.

Is the area of the sensor carrier plate 4 inserted into the fuel tank, the slider is 19 by means of the hook 20 moved to its upper end position, with the lugs 22 in the hook 23 engaged and by the spring cam 25 secured in this situation.

A not shown training has a radial on the slider projecting stop on the insertion of the level sensor in the insertion of the Fuel tanks comes to rest in the edge region of the insertion opening. In the further introduction of the level sensor the slide automatically shifts to its upper end position, so that a manual movement of the slider is eliminated.

It also the attacks 17 and 18 moved upwards, which causes the levers 11 and 12 apply and raise to their lower operating position ( 3 ).

When filling only the lower fuel level N1 of the fuel tank, the upper lever remains 11 in its lower operating limit during the lever 12 through the float 16 is pivoted upwards according to the level ( 4 ) and via its transmitter 8th generates a corresponding signal.

If a filling is also in the upper level range N2, the lever is located 11 in its upper operating limit and the lever 12 is by the float 16 pivoted upwards according to the level. If this is the maximum filling, both levers are located 11 and 12 in their upper operating limits ( 5 ).

The total level always results from a summation of the signals of both transducers 7 and 8th ,

Claims (8)

Level sensor, in particular for a fuel tank in a vehicle, comprising a container-fixed holding element, on which at least two lever encoders for detecting a level of a liquid in a container are each arranged pivotably, which lever encoder at least one transmitter for generating an electrical level signal, wherein by means of a first Lever a level of fluid within a first level range is detectable and above the first lever encoder in series with this at least one further second lever with a second level range for detecting a level of the liquid is disposed, wherein the individual level ranges at least immediately abut each other, the Lever each having a lever with a float, and container side each have a lower stop for the lever encoder to establish a lower operating position of the lever sensors respectively associated level area (N1; N2), characterized in that one with the stops ( 17 . 18 ) associated mounting device for installation of the level sensor in the container through an opening of the container is provided, wherein the with the lever ( 12 ) second, second lever ( 6 ) engageable bottom stop ( 18 ) for lifting the lever ( 12 ) is provided from a downward position in its lower operating position. Level sensor according to claim 1, characterized in that the lever ( 11 ) of the first lever transmitter ( 5 ) engageable stop ( 17 ) for lifting its lever ( 11 ) is provided from an approximately vertically downward position in its lower operating position. Level sensor according to claim 1 or 2, characterized in that the lever emitter ( 5 . 6 ) each have a transmitter ( 7 . 8th ) exhibit. Level sensor according to one of the preceding claims, characterized in that at least one transmitter ( 7 . 8th ) of a lever transmitter ( 5 . 6 ) a potentiometer with a thick film network ( 9 . 10 ) having. Level sensor according to one of the preceding claims, characterized in that a transmitter ( 7 . 8th ) of a lever transmitter ( 5 . 6 ) has a magnetic passive position sensor. level sensor according to one of the preceding claims, characterized that the levers of the levers each one with the respective Lever associated attacks have corresponding stop element. Level sensor according to one of the preceding claims, characterized in that the one or more stops ( 17 . 18 ) from its installation position in their end position the lever ( 11 . 12 ) relative to the level of the liquid lifting and can be limited in the end position to its uppermost operating position. Level sensor according to one of the preceding claims, characterized in that the stops ( 17 . 18 ) at a on the holding element between a lower container installation position and an upper end position vertically slidably guided slide ( 19 ) are arranged, which is fixable in its upper end position.