DE102005010398A1 - Gravimeter unit for detection using gravitational field analysis determines first data based on detected first position of first floating body or produced field, where first data correspond to first gravitational strength at first location - Google Patents

Abstract

The gravimeter unit (708-712) has a first floating body that is contactlessly held in floating state by the field generated by a field generating source. A first detector detects the first position of the first floating body. The gravimeter is adapted to determine first data base on the detected first position or the generated field. The first data correspond to a first gravitational field strength at a first location. Independent claims are included for the following: (A) Sensor for detecting material based on gravitational field analysis; (B) Filling level measurement of a filling good in a container based on gravitational field analysis; Program component for filling level measurement of filling goof in a container based on gravitational field analysis; and (C) Computer readable medium storing the computer program for filling level measurement of a filling good in a container based on gravitational field analysis.

Description

The The present invention relates to material detection by means of gravitational field evaluation. In particular, the present invention relates to a gravimeter unit for determining a gravitational field strength, a sensor for material detection by means of a gravitational field evaluation, a method for level measurement of a filling material in a container, the use of a sensor as a level gauge, the use a sensor as a proximity switch, a program element for level measurement and a computer readable storage medium.

From every massed body a gravitational field is generated, which is an attractive force other masses. In a spherical body with homogeneous mass distribution is that occurring on its surface Gravitational field proportional to the ball diameter and its density. Outside the body takes the field strength of its gravitational field with the reciprocal of the distance square to the ball center.

The Gravitational field of the earth, which acts as a fall acceleration, has on the earth's surface a value of about 9.81 meters per square second. A spherical volume of water 1 m in diameter creates a gravitational field on its surface, Compared to the Earth's field, it behaves as 1 to 70,000,000.

This Value is extremely low, let yourself However, with the help of a Gravimeterinstrumentes measure. These devices exist usually from a precision engineering Spring-mass system, on which the gravitational field to be measured acts. The feather is characterized by the gravitational proportional weight of the Mass element stretched, and their change in length, or a required compensation force for reaching a defined reference length, used as a measure of the applied gravitational field strength.

It are also heavy pendulum, float and Fallkörperanordnungen used for gravitational field measurement.

Next scientific applications, such as the measurement of the moon and Sun generated tidal forces, Gravimeter instruments are used primarily in search and exploration of natural resources like Oil, Gas, coal, ores and salts used. It is exploited that these materials usually have a different density to the normal underground rock or change its density, if they are contained in the rock spores.

In The area to be examined is followed by a gravimeter instrument the earth's surface moves, and the gravitational readings as well as their geographical Position recorded. The gravimeter can also attach to an airplane be mounted, which flies over the area to be examined. Furthermore, it is common Gravimeterinstrumente in boreholes Lowering the measured gravitational field values during the lowering process and related Record depth values.

The The result of these series of measurements are maps of geological gravity field anomalies represent, or depth diagrams which the field in the underground demonstrate.

Of the trained geologist can now use the created maps and diagrams, recognize existing density differences in the underground, and thus on the occurrence of deposits and their mining value Draw conclusions.

US Pat. No. 6,612,171 B1 discloses a gravitational instrument for measuring the gravitational field in boreholes in order to determine the density of formations in the underground. The disclosed gravitational measuring device is movable between two positions to perform a differential measurement.

The DE 689 15 45 T2 discloses a gravitational gradiometer. Hereby, extra diagonal components of a gravitational gradient tensor are to be measured, in particular a special bending bearing is disclosed.

WO 98/57197 also discloses a gravitational gradiometer. It explains that gravitational measurement is often done from aircraft to discover oil deposits. Appearing in the aircraft and thus acting on the gravitational gradiometer accelerations are in the in This document explained gravity gradiometer be compensated.

Alles the known gravitational measuring devices are suitable for use as industrially suitable Sensors for detecting quantity of material or for determining a filling level a filling material in a container not suitable. On the one hand, they are much too expensive, too voluminous and show only the gravitational field in a spatial direction. The issued Gravitational field display requires the interpretation of a specialist to derive further information from it.

Farther are response time and energy consumption of known gravity measurement systems for an industrial level sensor way to high.

It It is an object of the present invention to provide a sensor for direct Measurement and output of a level value provide.

According to one embodiment According to the present invention, the above object is achieved by means of a gravimeter unit solved for determining a gravitational field strength, comprising the gravimeter unit a first float, a first detector and a source for generating a field, the first float by a field generated by the source without contact in the balance durable is, wherein a first position of the float through the first detector is detectable, wherein the gravimeter unit is executed, first data based on the detected first position or the and the first data with a first gravitational field strength correspond at a first location.

advantageously, becomes a cost effective, miniaturized and high-resolution Gravimetermesszelle provided in which a gravitational field-detecting Mass element by means of electrostatic force fields contactless held in suspension in three dimensions. The need a mechanical spring element is eliminated.

Of the present invention according to this Aspect is based on the idea of a Schwebehalterung a float to measure the gravitational force acting on it. For example can the knowledge of the compensatory force that is necessary, the float in its original To hold position or due to its original position, in addition used, conclusions on on the float to draw acting gravitational force. Thus, the invention provides a cost effective, miniaturized and high-resolution Gravimeter unit ready, with which gravitational field strengths without mechanical spring elements or the like determined three-dimensionally can be.

The Floating mass element is preferably directly above a integrated semiconductor circuit arranged so that, for example Detector and source at least partially mounted directly on this can be.

According to one another embodiment According to the present invention, the field is selected from the group consisting from electric field, magnetic field, electromagnetic field and mechanical flow field.

advantageously, can thus over corresponding components, such as coils or capacitor plates, In a simple way fields are generated which the float in hold the balance.

According to one another embodiment of the present invention is the first detector for capacitive, inductive, conductive or optical detection of the first position of the first float carried out. The Capacitive position detection can for example via a second electrode, which for capacitance measurement between float and the second electrode is usable. According to one aspect of the present Invention, the float For example, be arranged within a cavity, which filled with a dielectric is. This can be the sensitivity increase the capacitive measurement or z. B. also the float stabilize. Naturally the capacitive position detection can also be done via a pair of electrodes.

For inductive measurement, for example, miniaturized coils can be integrated in the gravimeter unit, which generate a magnetic field which has an effect on the float. For example Induction currents can be generated in the float.

A Optical position determination offers the advantage, apart from the radiation pressure the photons, no additional personnel in the float couple. For example, you can here interferometric methods are applied as they are made the optics are known.

According to one another embodiment The present invention further includes the gravimeter unit a second float and a second detector, wherein a second position of the second float detectable by the second detector and wherein the gravimeter unit is executed, the first data based on the measured first position and the to generate measured second position.

advantageously, can by the use of two floating bodies within the gravimeter unit Calibrations performed or aging processes or temperature fluctuations Drift phenomena are compensated in the measured data.

in this connection It should be noted that the gravimeter unit, although the first Position of the first float and the second position of the second float determines it only a record is created, which reveals the gravitational field at Location of the gravimeter unit. The use of several floats in The gravimeter unit can thus ensure system accuracy and safety increase, but provides in the present case, only one common record.

According to one another embodiment The present invention further includes the gravimeter unit a control device, which for holding the first floating body in executed a starting position is.

For example For example, the control device may supply control signals to the source Send generation of the field, so that the field strength is varied accordingly, changed one Counteract gravitational acceleration and a deflection of the float from the zero position to compensate. The control variables, which for compensation changed Gravity accelerations can be used according to the invention in the Determination of gravitational field strength included.

According to one another embodiment The present invention further includes the gravimeter unit a memory device for storing reference values.

Farther Is it possible, these reference values in the course of a calibration of the gravimeter unit to store in the memory device and thus subsequent measurements simplify or calibrate. By attaching a Memory device in the gravimeter unit can exchange data between the gravimeter unit and external evaluation units or Display units are minimized.

According to one another embodiment The present invention is a sensor for material detection indicated by a gravitational field evaluation, wherein the sensor a first gravimeter unit, a second gravimeter unit and includes a communication interface. The first gravimeter unit is executed for determining first data, which with a first Gravitational field strength correspond at a first location. The second gravimeter unit is executed to determine second data, which with a second Gravitational field strength at a second location correspond and the communication interface is for transmission the first data and the second data to an evaluation executed.

The Distinction between a gravitational field, for example from a product to be detected goes out, and the rest Gravitational fields that originate from masses that are not measured are to be particularly advantageous in that the Gradient values of the gravitational field in the area of the to be measured filling material be determined and from their spatial Course the mass distribution in the immediate vicinity is determined.

advantageously, will according to this embodiment the present invention, the gravitational field strength in the Near the mass to be detected measured at different points in space. Because the distances between the gravitational measuring points and the mass to be detected can be known from the occurring field gradient values of Proportion of the measured sum field strength can be determined on the observation position for the unknown mass is omitted.

According to this embodiment The present invention provides an industrial sensor, in particular a tank level detection sensor that allows materials, in particular filled goods, contactless through closed tank walls to measure through. The tank level is determined by measurement and evaluation of the Füllguteigengravitationsfeldes determined by the sensor. Advantageously, all requirements Fulfills, placed on a sensor for use in industrial plants become.

For this is the Sensor built statically, without that a gravimeter instrument mechanically over a measuring distance or a surface is moved away. The generated measurement result does not need further processing or interpretation of a professional, but can be directly viewable fillingValue represent. This can be continuous, uninterrupted and in Real time available stand. The measurement result does not include geological or astronomical Components, such as fluctuating water content of the underground, tectonic mass displacements in the mantle or tidal forces, such as they are being measured by classical gravitational sensors. Likewise surrounding masses, such as people and vehicles, suppressed in the measurement result become.

According to one another embodiment The present invention bases the determined first data on first float position data or on first control parameters of a first control device. Furthermore, the determined second data are based on second float position data or on second control parameters of a second control device.

The Float position or also the control parameters, which are for example may be a voltage applied to a capacitor plate, represent easily measurable and accurately determinable data about which sound statements about appropriate, on the float acting gravitational forces can be taken.

According to one Aspect of the present invention are the first and the second Gravimeter unit relative to each other at fixed positions in the sensor arranged. Furthermore you can the two gravimeter units are factory-spaced such that optimal measurement for For example, a very specific container is possible.

According to one another embodiment According to the present invention, the first gravimeter unit is one Axis rotatable or displaceable along an axis, while during a rotation or shift continuously recorded data which are at the detected first positions or the generated Fields are based within the gravimeter unit. This recorded Data can then into a volume dataset that summarizes the topology represents a gravitational field. About this Volume data set can thus conclusions on a local one Mass distribution can be drawn in the vicinity of the sensor. to Evaluation of the data set and imaging can be done from known methods e.g. used in computed tomography.

According to one Aspect of the present invention, the sensor comprises a plurality of gravimeter units arranged in a line-like, plane-like or spatially are, so that a one-, two- or three-dimensional record is determined which represents a gravitational field distribution.

Farther the sensor may comprise an evaluation unit, which is for receiving the first data and the second data from the communication office accomplished is, wherein the evaluation unit for calculating a gradient of a Gravitational field based on the first data and the second data accomplished is.

According to one Aspect of the present invention, the evaluation unit, for example together with the sensor on a semiconductor chip in the form of an integrated Circuit formed. Naturally it is also possible that the evaluation unit is arranged externally and the data from the communication interface via for example, a radio transmission or another wireless data transmission method. Of course you can the communication interface also via a data line with the Be connected evaluation.

According to one another embodiment The present invention is the use of a sensor according to the invention as a level gauge specified. Therefor can the sensor in the vicinity a container be arranged and the level inside the container measure up.

Furthermore, according to one aspect of the invention, the sensor may be used as a proximity sensor be detected, for example, whether a door is open or closed, or how far a corresponding object is removed from the sensor or at what speed he approaches the sensor.

According to one another embodiment The present invention is the use of a gravimeter as a level gauge specified, for example, a method for level measurement according to a embodiment of the present invention.

Also can, according to one Aspect of the present invention, a gravimeter as a proximity sensor application find, for example, for the detection of distances.

According to one another embodiment The present invention is the use of a gravimeter unit according to the invention indicated as an accelerometer, which is used to measure accelerations, for example within a vehicle, airplane or another moving or vibrating object, such as a person or a machine is used.

According to a further exemplary embodiment of the present invention, a method for measuring the filling level of a filling material in a container by means of a gravitational field evaluation is provided, the method comprising the following steps:
Determining first data corresponding to a first gravitational field strength at a first location by a first gravimeter unit; Determining second data corresponding to a second gravitational field strength at a second location by a second gravimeter unit; Calculating a filling level of the filling material on the basis of the determined first and second data.

advantageously, allows the use of a gravitational field evaluation for level measurement a non-contact Measurement which does not require contact with the measurement object. Farther is for the inventive method no radiation source or the like necessary, which a Emitted measuring beam, which, for example, subsequently from the filling is reflected, so that below statements about the level height can be made. Much more uses the inventive method the measurement of gravitational fields generated by the contents become. An introduction of the sensor in the container is not required. Also, no energy is introduced into the medium by the measurement.

According to one further embodiment The present invention is a method for receiving a Volumetric data set in which the first unit of the gravimeter is rotated about an axis or moved along an axis. Also, a combination of displacement and rotation can be done, so that the gravimeter unit extends along any one or three-dimensionally moving web can move. During the movement the gravimeter unit creates a first volume data set which includes the first data. To carry out this exemplary Procedure is only one gravimeter unit necessary, but it can also be provided a plurality of gravimeter units, which, for example can lead to a faster recording of the volume data, or also movement dimensions saved in the course of the course allowed.

The The present invention also relates to a program element for level measurement a filling in a container by means of a gravitational field evaluation and a computer readable Storage medium on which a computer program for level measurement a filling material in a container is stored by means of a gravitational field evaluation. in this connection The computer program initiates a processor, a method according to a embodiment of the present invention, if it is on the processor accomplished becomes. The program element according to a embodiment The present invention may preferably be in the working memory of a data processor. The data processor can be executed exemplary embodiments of the method of the present invention. Farther can the computer program in any programming language, such as C ++, can be written and stored on a computer-readable storage medium, such as a CD-ROM. Furthermore, can the computer program over a network available such as the WorldWideWeb, which makes it into a processor or computer can be loaded.

Further Tasks, embodiments and advantages of the invention will become apparent from the dependent claims and the sibling claims.

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

1 shows a cross section through an exemplary embodiment of a gravimeter unit according to the present invention.

2 shows a plan view of a semiconductor chip with electrodes applied thereon in 1 illustrated embodiment of the invention Gravimetereinheit.

3 shows a cross section through a further embodiment of a gravimeter unit according to the present invention.

4 shows a plan view of a semiconductor chip with electrodes of the in 3 illustrated embodiment of the gravimeter unit.

5 shows a cross section through an embodiment of a gravimeter unit according to another exemplary embodiment of the present invention.

6 shows a schematic side view of a gravity level limit switch, which is mounted horizontally mounted on a side of a product container, according to an embodiment of the present invention.

7 shows a schematic cross-sectional view of a partially filled product container, are mounted on the five different types of continuously measuring sensors according to embodiments of the present invention.

8th shows another embodiment of a gravimeter according to the present invention.

9 shows another embodiment of a gravimeter according to another embodiment of the present invention.

1 shows a cross section through an exemplary embodiment of a gravimeter unit according to the present invention, which will be explained in more detail below. Several of these gravimeter units can be integrated into a level sensor or level switch. A corresponding embodiment is in 6 shown.

6 shows a schematic side view of a gravity level limit switch, which is mounted horizontally mounted on a side of a product container, according to an embodiment of the present invention.

Of the Inventive level sensor contains at least 2 gravimeter units G1, G2, which are attached to solid Positions on, or in the immediate vicinity of, to be measured product container mounted are. To compensate for varying gravitational distant fields whose Origin not in level changes The field strength measured values are used for signal processing of the 2 or more gravimeter units subtracted from each other. The Felddifferenzwertbildung is doing directionally selective, the is called, they are field components, each with the same orientation with respect to to subtract x, y or z space axis from each other.

Depending on the number of gravimeter units and their positions on the product container, the filling level value is determined from the field differential values according to various methods, shown below. For gravitational field measurement, a novel miniature gravimeter is used. An embodiment thereof is in 1 shown.

The Distinction between the gravitational field to be detected by the one to be detected filling goes out, and the rest Gravitational fields that come from masses that are not measured are particularly advantageous in that the gradient values of the gravitational field in the region of the product to be measured be determined, and the spatial distribution of the mass distribution in the nearer Environment is determined.

There the gravitational field of each body, outside of this, with the Inverts the distance square to its center of gravity decreases in its nearer Environment a significantly larger percentage Field strength decrease per unit length, as this is the case further away.

The Gravitational fields of different distant body possess thus an individual spatial gradient change, and can therefore be distinguished on the basis of this.

A near small mass with very weak self-gravitational field, can therefore because of their large Feldgradientenänderungswertes, despite the dominant strong earth field, its gradient change value However, by many orders of magnitude lower, metrologically recorded become.

To For this purpose, the gravitational field strength in the vicinity of the Detecting mass measured at different points in space. Because the distances between the gravitational measuring points and the mass to be detected can be known from the occurring field gradient values, that proportion of the measured sum field strength can be determined, the the observation position for the unknown mass is omitted.

For many Applications in practice are sufficient it, if the gravitational measuring points on a straight line located on the mass to be detected.

at such a gravitational field sensor register the individual Gravimetry cells dependent their distance to the target object, a differently weakened object field strength. The weakening is due to the high field gradient change value in the near range of the measurement object clearly nonlinear.

Further By contrast, remote objects generate, depending on the spatial orientation of the sensor, either all the same field strengths in the measuring cells, or because of their low field gradient change values in the far field, a nearly linear field decrease along the measuring cells. By appropriate Mathematical processing of the cell readings can be done by the sensor electronics to calculate the far fields.

gravitational fields subject as opposed to electromagnetic and acoustic Do not wave the physical phenomena of absorption, reflection, Dispersion, interference, diffraction and refraction.

by Lights If you use a human hand with a light source, you are allowed to Again, light escaping it does not recognize the bone structure. Even when using the most advanced optical sensors and the most complex data processing algorithms, it is impossible to create a bone image in this way. The reason is that the above mentioned physical effects have destroyed the information content of the light.

There when passing a gravitational field through a layer of matter none of these effects has an effect, the information content the passing field in no way changed. This means that the gravitational field of a behind a thick lead plate set up Glass of water, the plate passes through completely unchanged, and therefore it does not matter if it is present or Not. The lead plate adds only to the already existing in space gravitational fields their own added.

There each of the fields has its own origin in space is through Evaluation of the spatial Field distribution a separation possible.

It depends therefore only by the accuracy and resolution of the available Gravity sensor technology, whether it is possible through the lead plate to see how full the glass is, or even what shape it has.

in the The first is the measurement according to the invention of level limit values by evaluation of the Füllguteigengravitationsfeldes described.

Level sensors should report the achievement of a certain fill level. To this end the sensor is outside on the container wall at the height of the level value to be reported. His job is one spatial Limited volume on the presence of Füllgutmasse to monitor. Crowds outside of the container are allowed to not be displayed.

One Level Switches includes, for example, three gravimeter circuits with which the gravitational field strength measured at three different points. The points are preferably on a straight line that points to the level to be measured. Out the three obtained measurements can two adjacent field gradient values determined by subtraction become.

While the field strength proportional to the product diameter grows, the field gradient on the product surface is independent of Diameter of the product volume. Both the field strength as well as the gradient are both proportional to the product density. With increasing distance from the product surface take field strength and Field gradient. The degree of distance-related decrease of both Parameter is dependent from the product diameter and thus the container size.

at fixing the mounting distance of the three gravimeters inside of the level sensor Therefore, the area of the container diameter to be covered must be taken into account.

Becomes the distance chosen too large, so the sensor can through small containers look through it so that masses behind it are detected become. If he is elected too narrow, so give great container only small signal differences between the gravimeters.

There If the gravimeters do not influence each other, you can extend the range of application additionally a fourth gravimeter at a greater distance be provided in the sensor.

6 schematically shows a gravity level limit switch is mounted horizontally on a side of a product container.

The gravimeter circuits in the sensor housing are labeled G1, G2, G3. The distances a ₂ , a _{3 of} the gravimeters to each other, for example, each 20 mm. The distance a ₁ between the first gravimeter G1 and the product container is, for example, 10 mm and the distance a ₄ to the sensor housing rear wall is, for example, 80 mm. The mass of the product container m (B) is for example 1 kg, with a diameter of 0.124 m, the masses of the interference elements S ₁ and S ₂ are, for example, each 100 kg, with a diameter of 0.58 m. Of course, quite different distances, densities and masses can be chosen.

The Sensor signal processing detects the presence of a filling material on the one hand, that the field gradient between the two next Gravimetern the product a certain height owns what a sign for that is that there is a sufficient mass density, on the other hand, that of the contents more distant field gradient in a certain way lower than the first Gradient is what is a sign that the detected Mass in the immediate vicinity and right direction.

to Elimination of fluctuating far fields forms the sensor signal processing First, the difference values (G1 - G2) and (G2 - G3) of the in the direction of the measuring lines lying field strengths. These values are the field gradient proportional in the corresponding distance interval.

Then be by height of the first difference value, of the signal processing two permissible value ranges for the determined second difference value. Is the second difference value in the first value range, the sensor outputs an empty message. If the value is in the second value range, the output is a Full message. If the second difference value is not assigned to either of the two Contain value ranges, there is a malfunction, and the sensor gives fault message out.

Should The sensor can be equipped with a switching hysteresis, this can by using different value ranges for the empty / full and full / empty changes happen.

at Sensors acting as maximum level or minimum level safety limit switches can be used, it can be useful to each of these two modes assign their own value ranges to that for the respective operating mode safe sensor output value to give a signal output preference.

through stored in the sensor mathematical functions, which the first Have difference value as input, can the sensor electronics the limits of the allocation ranges of calculate the second difference value to the output states Empty / Full / Fault.

It is also possible, instead of mathematical functions, to store a table of values in the sensor, from the the sensor signal processing can read out the corresponding range allocation limits for the second difference value on the basis of the first difference value. To limit the value table size, a reasonable number of input values are used, and interpolated at intermediate values according to known methods.

It there is also the possibility the required minimum height of the first difference value and the range allocation limits for the second one Difference value, in addition based on entered measurement application properties such as vessel diameter or to adjust the product density to the current measuring task.

As well Is it possible, when filled container to perform a full match to the signal evaluation parameters to the actually occurring field difference values to adapt.

On the basis of in 6 The measuring arrangement shown below, the influence of moving external masses and their removal is shown from the measurement result.

Of the in the example used product container is very small and contains filled only a quantity of goods of 1Kg weight. The task of the laterally mounted sensor is the presence of this quantity, unaffected by variable surrounding Masses, safe to display.

To illustrate the influence of moving mass bodies, are in the 6 the disturbing masses S ₁ and S ₂ drawn. By way of example, these are two persons who are very overweight and have a spherical belly of 100 kg each. Both persons assume the most critical position for the measuring arrangement, in that their center of gravity is located exactly on the measuring line of the three gravimeters G1, G2, G3. The first person (perturbation mass S ₁ ) is for this purpose exactly on the back of the container, the second person (perturbation mass S ₂ ) touched with her body directly from the rear of the sensor housing.

The Density of the contents and the masses of disturbances is assumed to be 1 g / cc (water). All the masses have due For ease of calculability, a spherical volume. The container wall has one Thickness of 10 mm.

Table 1

table 1 shows by means of 7 different mass combinations the occurring Field strength values the three gravimeters and the calculated difference values. The field strengths are given in nanometers per square second and apply in the direction the measuring line.

The The first 3 lines of the table show the field values when the container is empty and existing disturbing masses. The fourth line shows the field values when the container is full without the disturbance masses. The last 3 lines show the field values with full tank and Disturbing masses.

you recognizes that in the case of the disordered masses without filling, Although the first field difference value clearly refers to an existing mass indicates, the difference to the second difference value but only minimal is.

This means that the detected mass is outside of the observed Room volume and therefore may not be displayed.

In the case of the perturbations with filling material, it can be seen that both the first difference value high, and the Difference to the second difference value is large enough for the desired full message.

Even though the disturbance masses in the example, both were 100 times as large as the contents of the product, the Gravitational field sensor the level show correctly.

The Values of Table 1 also show that using only 2 instead of 3 gravimeters, a distinction between the contents and the listed disturbing masses not possible would.

at particularly critical applications such as low density products, or Measurements through thick container insulation layers, can for disturbing mass suppression of Use of 4 sensor-internal gravimeter circuits required become.

There the measuring method described selectively the gravitational fields in Evaluate the direction of the measuring line, go disturbing masses whose focus is not spatially is on the measuring line, only diminished or not at all Measurement on.

When Second is the measurement according to the invention of continuous Fill levels by evaluation of the Füllguteigengravitationsfeldes described.

The Measurement of continuous level values can be done by four different methods of field evaluation. These methods can individually or combined in a sensor.

7 shows a schematic cross-sectional view of a partially filled product container, are mounted on the five different types of continuously measuring sensors according to embodiments of the present invention.

The first method is based on the evaluation of the field strength difference in between the gravimeters befindendem contents.

For this purpose, preferably a first gravimeter is attached to the underside of the product container and a second to the top. This sensor type is in 7 with the numeral 701 designated.

is the container empty results in a difference in reading between the two gravimeters, which corresponds to the earth field gradient multiplied by the container height. This value is removed from the measurement result by means of zero compensation.

Becomes the container filled, this is how the contents gravitational field works at the location of the lower gravimeter against the Earth's field, so that its measured field strength falls. At the location of the upper gravimeter, the filling material field adds to the earth field, so that its field strength increases.

The measured field strength difference between both gravimeters results after suitable measured value linearization one of the container filling material proportional level indicator.

It is possible, too, the two gravimeters on two opposite side walls of the To be attached to the product container. In terms of However, the exact detection of the empty and full state is the mentioned earlier Mounting method preferable.

The Measurement result is of the product density dependent.

The second method is based on the evaluation of the field strength decrease in increasing distance to the product.

The gravitational field outside of the contents decreases, according to the law of gravity, with the reciprocal of the distance square to its center of mass. The degree of distance-related field strength change is both a measure of the Füllgutdurchmesser as well as the distance to the contents. A sensor operating on this principle contains several line-mounted gravimeter circuits. The assembly line preferably points to the filling center of gravity. This sensor type is in 7 with numeral 702 designated.

sensor 702 includes, for example, five gravimeter units 708 . 709 . 710 . 711 and 712 , which are arranged vertically one above the other. The sensor can be mounted both on and under the container. Furthermore, the sensor comprises a communication interface 713 which has, for example, a transmitter. Via the communication interface 713 can records, which, for example, on measurement data of the gravimeter units 708 . 709 . 710 . 711 and 712 based on an external evaluation unit 715 with receiver 714 by radio transmission 716 be sent. Of course it is also possible to use the evaluation unit 715 into the sensor, and then, for example, an evaluation result (eg filling level height) via interface 713 to an output unit or to a device for further processing.

The Sensor signal processing calculates by means of the measured field values, and the known physical gravitational field distribution laws outside of mass bodies, the distance to the product or its height.

Become a total of only 2 gravimeters used, so only 2 are different from the product focus spaced field measurements available, the difference of which can only calculate a field gradient. The derivable from it Level measurement is as a result of the filling material density dependent.

Preferably Therefore, at least 3 gravimeters are used, from their field measurements At least 2 spatially different field gradients can be calculated. From these at least 2 Felgradientenwerten the level independent of density be determined. The 3 unknown parameters in this case, filling level, filling density and far field amplitude, require at least to solve the measurement problem 3 gravimeters that provide 3 different field measurements.

at The initial commissioning of the sensor is an empty product container Zero balance to perform near-field static components, such as the empty mass of the container to remove the measurement result.

The third method is based on the evaluation of the field strength distribution within the product or along its boundary surfaces. The generated by a spherical filling material Field takes, according to the Gravitatationsfeldgesetz, from the center of mass to the product surface linear to, the field strength is within the contents proportional to the center of gravity distance. For non-spherical contents are the ratios more complicated, yet strictly physically legitimate.

At the center of gravity, its inherent field strength is generally zero. The sensor 703 includes several gravimeters mounted on a line 718 . 719 . 720 . 721 . 722 which are located in a common protective tube. The sensor is mounted so that it preferably dips into the medium, but it can also be mounted vertically to the container side wall. Goes with a dipping sensor 703 the assembly line of the gravimeter through the center of gravity, this is particularly advantageous, but by no means a condition.

The Sensor signal processing calculates based on the field strength difference values between the individual gravimeters, and the well-known physical Field distribution laws within mass bodies, the level value. By execution a zero balance, static near field components are compensated. Become Only 2 gravimeters used, the level measurement result depends on the filling density. Stand at least 3 spatially different field measurements available, so can the level independent of density be determined.

The depending on level just not submerged gravimeter of the sensor, can do so to be used the level additionally to determine by method two. Likewise, it is advantageous to the Value of the last immersed gravimeter with that of the first one not to charge more submerged gravimeters according to method one. By combining the result values of all used procedures let yourself increase the measuring accuracy of the sensor.

Of the Advantage of this type of sensor immersing level rod probes Other physical measuring principles is that the sensor through one into the container built-in separation tube that protects him from the contents, can measure through.

For transport containers insertable sensors can be realized. In the container, a one-sided closed and open to the outside separation pipe is installed. During filling and other control purposes, the gravity sensor is temporarily pushed in and measures the level through the separator tube. The container remains hermetically sealed. In the example of 7 is one Separating pipe miteingezeichnet.

The fourth method is based on the evaluation of the spatial position of the gravitational field vector. Such a sensor is in 7 with numeral 704 designated.

Lying with a sensor 704 Due to the installation, the individual gravimeter positions are not on the ascending line of the center of gravity, so the gravitational field vector acting on the gravimeters changes not only its length but also its orientation in space.

Of the Three-dimensional gravitational field vector is formed by the orthogonal field components in the x, y and z directions. The z field points in filling height direction and is perpendicular to the ground. The x and y field, on the other hand, runs parallel to the ground. The x-field should be the gravitational component towards the tank center represent and the y-field the component parallel or tangential to the container wall on Represent the mounting location of the sensor.

Is the sensor 704 mounted centrally on the side wall of a symmetrical container, so register the Gravimeter when filling a field in the x and z directions. A y-field component does not occur because due to the central sensor mounting, the individual y-fields cancel each other out at the sensor location. In the case of non-centered mounting, the filling material generates all three field components at the gravimeter positions. The amplitude ratios of the orthogonal field components at the gravimeters or the angular orientation of the resulting gravitational field vector in space is characteristic for each individual fill level value and thus the fill height can be derived therefrom. Since the amplitude ratios are evaluated, the absolute amplitude values do not enter the measurement result, so that this filling density is independent.

Every gravimeter in the sensor 704 determines the components of the gravitational field in the three spatial dimensions. The field strength values obtained in this way are freed from fluctuating far fields by forming difference values between the gravimeters. A zero calibration when the sensor is put into operation serves to eliminate the static ambient gravitational field. From the difference field strength values obtained in this way and the known positions of the gravimeters, the sensor signal processing calculates the position of the contents and thus the level value. Also, this fourth method is, depending on the structure of the sensor 704 , combinable with the other 3 methods.

The in 7 with numeral 705 For example, the designated sensor consisting of two gravimeter units mounted on the container side wall employs methods one and four, for example.

Next the calculation of the filling height from the Gravimetermesswerte by application of the known physical Field distribution laws under consideration the mounting positions of the gravimeters and possibly additionally entered Container data there is also the possibility the filling level from the current gravimeter readings by comparison with previously stored Gravimeter readings during a commissioning filling to determine.

Of the containers to be measured is for this purpose, after mounting the sensor, gradually filled, and after each filling step the present filling level to the sensor communicated. This saves to the entered level value the occurring gravitational measurements of all gravimeters. At the later Measuring mode now compares the sensor signal processing currently measured gravitational values with the stored support values and interpolates the level closest to each other lying memory values.

at The methods 2 to 4 are preferably not the absolute sizes of the Field difference measured values compared to each other, but the ratio values the individual field differences to each other. That way also filled goods, with one for commissioning deviating medium density, measured exactly.

By the application of several of the methods 1 to 4 in a sensor, can the level be determined several times by different methods. The averaging the individual measurement results lead to an elevated one Measuring accuracy of the sensor.

at Occurrence of a disturbing mass Depending on the position of the mass, the individual methods react differently sensitive to this. The averaging of several methods therefore increases additionally the insensitivity to Disturbing masses.

It is possible, too after execution a plausibility check of the individual measurement results, a result of inaccurately recognized exclude earnings averaging.

By Use of more gravimeters and thus field strength measuring points in one sensor as theoretically required, is also an over-determination the level possible. Also offer extra Gravimeter the possibility to reduce the field measuring point distance, so that the near field measuring range of the sensor is reduced and possible disturbing masses rather than unproblematic Far fields work.

The Choosing a cheap one Mounting position of the sensor on the product container additionally increases the Noise immunity.

Next These passive methods influence the influence of disturbing masses on the measurement result to suppress, there is also the possibility the disturbing mass and then calculate them out of the final result. requirement for this procedure is a sufficiently large number of field measurements, and thus input variables, for the correction algorithm.

The Number of required Gravimeter in a continuous level sensor also hangs from the shape of the container from. Slim and irregular shaped container can require more gravitational measuring points and thus gravimeters than flat simple containers.

At the in 7 with numeral 704 designated sensor, the gravimeters are surrounded by a common metal tube. The sensor is therefore only suitable for mounting on straight container walls. If the gravimeters are integrated in a flexible band, the sensor can also follow curved container walls. In addition to these pre-assembled sensors, individual gravimeter units can also be attached to the vessel wall at regular intervals, and connected to the evaluation electronics of the sensor via a two-wire data bus cable. The individual gravimeters are preferably connected by means of cable penetration technology to a rubber-like ribbon cable with a rectangular cross-section. The continuous bus cable must therefore neither be severed nor stripped.

For sensors that consist of a few gravimeter units, such as the type 701 and the guy 705 in 7 , an existing fieldbus can also be used for data exchange. All units are interconnected via the fieldbus. The slave units send their measured gravitational values directly to the bus, the master unit reads them back from the bus, calculates them with their own gravitational measurements to the level value, and outputs them to the bus.

On Base of the later described Miniaturgravimeterschaltkreis and modern radio transmission method is also the development and application of wireless sending gravimeter units possible.

These equipment For example, consist of the gravimeter circuit, a highly integrated Radio interface and a long-life lithium battery as a power supply. The volume of this unit is the size of a matchbox or even smaller. The gravimeter units are in the required number glued to the appropriate places on the container. One away mounted evaluation unit receives the measuring data of all gravimeters and calculates them to the filling level value. It is sufficient while an evaluation to the data from a plurality of containers to receive and calculate their levels.

A further miniaturization is possible by means of technologies such as they used on smart credit cards and merchandise labels become. With that could The Gravimeterereinheiten designed as a flat, flexible sticker become. Inside is the Gravimeterchip, the Send chip, a planar antenna, a lithium polymer battery and possibly an amorphous solar cell for battery charging.

The area is for example, 1 cm by 4 cm, the thickness of about 1 mm. With these sensory Stickers can then container and piping in revolutionary be instrumented easily. A central receiving unit then calculates all level values and gives them to the process control.

is it is possible by means of special gravimeters, in a gravimeter unit multiple gravitational field strengths to measure at different places or directly their difference value are the gravitational field measurement point arrangements described above and the associated ones Gravitational field evaluation method according to the same sense on such Gravimeter units transferable, without thereby leaving the subject invention.

Level measurement based on gravitational fields offers the following features and application advantages:
All liquids and liquefied gases can be measured. Bulk materials must have a minimum density, the grain size does not matter. The measurement can be made through the closed container wall, all wall materials are suitable. This is particularly advantageous for corrosive, abrasive, explosive, germ-free, toxic, biohazardous, radioactive and ultrapure products, as well as for high-pressure tanks.

Very name is and become very cold products measured through the tank insulation. As the measurement method reacts to mass quantities, product adhesions, dirt deposits and foam ignored. It is therefore also suitable for particularly sticky and viscous products. Fillings the tend to very strong electrostatic charges, can the outer wall Do not damage mounted sensors still add product.

The Application in explosion-proof Areas is easily. There is no energy coupled into the product. Sensor power supply and measured value transmission are via one intrinsically safe 4 ... 20 mA current loop possible.

vessel installations like impellers, baffles, Baffles, Heating and cooling coils, Coil, perforated shelves, Gas injector lances, catalyst carrier plates as well as packed beds are penetrated by the gravitational field unchanged, so that behind and below the contents are measured easily.

Next the mounting on the outside wall can Gravimeterensoren also screwed into the container wall or be flanged. Certain sensor designs close in this Hang in flush with From the wall, so that no narrowing of the withdrawal cross-section of containers or the flow cross-section of pipes occurs. Small screw thread the size M8 are possible.

sensors the outside on the container can be mounted be replaced or retrofitted without interruption of plant operation.

The construction of a novel miniature gravimeter according to the invention will now be described, as illustrated as exemplary embodiments in FIGS 1 to 5 is shown, and which is particularly advantageous for use in industrial plant sensors.

The Technique of classical precision mechanical Gravimeters, as they are used in the field of geology, is for applications not only much too expensive and in industrial metrology the response time too slow, especially disturbing that is way too big Volume. This not only prevents the realization of a compact Sensors, but lets also the needed punctate Gravitational field determination at close intervals not too.

One Another disadvantage of the classic gravimeter is the fact that they are able to measure the gravitational field in only one spatial direction. For a three-dimensional Field determination thus requires 3 of these devices. In addition to the would be immense cost Such a configuration also does not measure the 3 field components allow at the same point in space.

a integrated step in the right direction Micromechanical acceleration sensors. In these sensor elements is by means of etching from a silicon substrate, a bending beam structure with integrally formed Mass element generated. By capacitive distance measurement, the deflection of the bending beam detected and by means of electrostatic compensation force field the bending beam zero position restored. From the required compensation field strength is won the measurement result.

Of the The disadvantage of these sensor elements is that they are suitable for gravitational field measurements needed Accuracy and resolution do not reach.

The spring constant of the bending beam structure can not be reduced arbitrarily, since otherwise plastic deformations occur, resulting in a loss of zero stability. In addition, complex micromechanical structures are generally subject to a large number of defect influences. It is also disadvantageous that mechanics and electronics must be produced on the same material substrate, so that both components can not be manufactured optimally. For a three-dimensional field measurement would also be in this case three orthogonally mounted measuring elements required.

The Realization of a cost-effective, miniaturized and high-resolution Gravimetermesszelle according to the invention is characterized in that the gravitational field detecting Mass element by means of electrostatic force fields contactless held in suspension in three dimensions. The need a mechanical spring element is eliminated.

The Position of the mass element is determined capacitively. The floating Mass element is preferably directly above an integrated Semiconductor circuit arranged so that at least part of the required field-generating and measuring electrodes mounted directly on top of this can be. From to maintain a defined hovering position the mass element required electric field strengths let the values of the gravitational field strengths in the spatial directions calculate.

The 1 and 2 show a first embodiment of such a Schweighörpergravimeterzelle.

1 shows a cross section through an exemplary embodiment of a gravimeter unit according to the present invention.

2 shows a plan view of a semiconductor chip with electrodes applied thereon in 1 illustrated embodiment of the invention Gravimetereinheit.

On a semiconductor chip 101 which includes the signal processing electronics is a molded part 102 attached, which has two conical depressions. The molding 102 consists of non-conductive insulating material such as glass or ceramic. In the two cavities formed by the depressions, there is in each case a conical metallic body 100 . 200 , Its diameter is for example 0.5mm. In order to allow him to act in all three spatial directions electrostatic forces, eight electrodes, each of the shape of a quarter-circle segment, are mounted inside the cavity. One half of it is located on the semiconductor chip 101 and forms the base electrodes 113 . 213 . 1 . 2 . 3 . 4 . 201 . 202 . 203 . 204 the other half is on the inside of the conical recess on the molding 102 metallized and forms the side electrodes 115 . 116 . 215 . 216 , The side electrodes are on the lower part of the molding over the contact surfaces 117 . 217 with the chip 101 electrically contacted. references 118 . 119 . 120 denote filler material.

2 shows the chip surface with the base electrodes and the contact surfaces 5 . 6 . 7 . 8th . 205 . 206 . 207 . 208 to the side electrodes.

The gap 108 between float 100 . 200 and chip 101 or molded part 102 who in 1 can be seen acts as a dielectric for the electric field. The dielectric 108 consists of either vacuum, an inert gas such as nitrogen or a non-conducting liquid with preferably high dielectric constant. The use of a liquid offers, in addition to the values of the capacitances and electric field forces increased by the relative permittivity, also the advantage of the good damping of mechanical vibrations by viscosity-dependent fluid friction. The gap width is small and is for example 0.005 mm.

By applying a voltage between the base electrodes 113 . 213 . 1 . 2 . 3 . 4 . 201 . 202 . 203 . 204 The float is electrostatically pulled down. A voltage between the side electrodes 115 . 116 . 215 . 216 , pull him up. If one side of a voltage between a base and side electrode applied, the float is pulled to the appropriate side. By suitable electrode control can also generate rotational tilting moments.

to Coupling of the electrostatic forces can be both DC and AC voltages are used.

The Capacitive distance measurement to determine the exact position of the float is preferably over the same electrodes are running, which also serve the power input. It should be noted that the high-frequency measurement field also generates attractions.

The measurement and control electronics on the semiconductor chip now ensures that the float is held in an exact position of symmetry to the electrodes. The force acting from outside through the gravitational field on the float gravitational force is by a counter-directed electrostatic Kompensati onskraft lifted. The required compensation force in the three spatial directions is thus a measure of the gravitational field in the three spatial directions.

The used drive voltages of the individual electrode segments are preferably chosen that is on the float sets a median ground potential. For this purpose, the one Half of the Electrodes with a positive voltage level to center ground and the other half driven with corresponding negative level to the center mass.

There the float the applied electrostatic forces integrated over time, in addition to analog drive voltages, also digital pulse width modulated Binary- or Ternärlevelspannungen used become.

m

= Kegelmasse

d

= Kegeldurchmesser

h

= Kegelhöhe

V

= Kegelvolumen

ρ₁

= Kegeldichte

ρ₂

= Dielektrikumdichte

g

= Gravitationsfeldstärke

F_A

= Auftriebskraft

F_G

= wirksame Gewichtskraft

Elektrostatische Kräfte F_EL der einzelnen Elektroden:

ε_o

= Elektrische Feldkonstante = 8.85·10^–12 F/m

ε_r

= Dielektrizitätszahl des Dielektrikums

A

= wirksame Elektrodenfläche bezogen auf eine Raumrichtung x, y oder z.

U

= Spannung zwischen Elektrode und Schwebekörper

s

= Dielektrikumspaltweite

n

= Anzahl der Basis – oder Seitenelektroden

l

= Sehnenlänge der Seitenelektroden

x,y

= Raumrichtung parallel zu den Basiselektroden

z

= Raumrichtung senkrecht zu den Basiselektroden

Elektrodenansteuerspannung zur Kompensation der Gewichts- bzw. Gravitationskraft:

U_x

= Ansteuerspannung einer Seitenelektrode um ein Gravitationsfeld in x-Richtung zu kompensieren

U_z

= Ansteuerspannung aller Basiselektroden oder aller Seitenelektroden um ein Gravitationsfeld in z-Richtung zu kompensieren.

The following are the physical calculation formulas for an idealized hover cone gravimeter. Furthermore, it is shown on the basis of a calculation example, which height the electrode drive voltages occurring in practice have for the gravitational field compensation, and which electrode capacitance values result. Buoyancy and effective weight of the float:

m

= Cone mass

d

= Cone diameter

H

= Cone height

V

= Cone volume

ρ ₁

= Cone density

ρ ₂

= Dielectric density

G

= Gravitational field strength

F _A

= Buoyancy

F _G

= effective weight

Electrostatic forces F _{EL of} the individual electrodes:

ε _o

= Electric field constant = 8.85 · 10 ^-12 F / m

ε _r

= Dielectric constant of the dielectric

A

= effective electrode area with respect to a spatial direction x, y or z.

U

= Voltage between electrode and float

s

= Dielectric gap width

n

= Number of base or side electrodes

l

= Chord length of the side electrodes

x, y

= Spatial direction parallel to the base electrodes

z

= Spatial direction perpendicular to the base electrodes

Electrode drive voltage for compensation of the weight or gravitational force:

U _x

= Drive voltage of a side electrode to compensate for a gravitational field in the x direction

U _z

= Drive voltage of all base electrodes or all side electrodes to compensate for a gravitational field in z-direction.

Capacities between Electrodes and floats:

• C _B

  = Capacity of one base electrode

  C _S

  = Capacity of one side electrode

  A _S , A _B

  = Areas of electrodes

Gravitational field calculation

• G

  = Gravitational field and the surface a spherical one property

  y

  = Gravitational constant = 6.67 x 10 ^-11 m ³ / kg.s ²

  m

  = Mass

  r

  = Ball radius

  V

  = Volume

  ρ

  = Ball density

example

The Gravimeter is mounted on the side of a spherical tank. The cone top points down.

The filling material field acts in the x-direction. The earth's field acts in the z-direction. The product is water. Given values: product density p = 1000kg / m ³ tank radius r = 0.5 m Cone diameter d = 500 μm cone height h = 250 μm cone density ρ ₁ = 2700kg / m ³ Dielektrikumdichte ρ ₂ = 700kg / m ³ gap width s = 5 μm number of electrodes n = 4 permittivity ε _r = 20 Earth's field g _E = 9.81 m / s ² Calculated values: Base electrode capacitance C _B = 1.74 pF

Side electrode capacitance C _S = 2.46 pF Füllgutgravitationsfeld g _F = 1.4 × 10 ^-7 m / s ² driving voltage for the bases U _Z = 680 mV driving voltage for the the contents facing away side electrode U _X = 171 μV

As the calculation example shows sufficient to generate the electrostatic compensation forces Voltages of low value, allowing operation of the measuring cell electronics at a usual 5 Volt supply voltage is easily possible.

There the hover gravimeter inherently no mechanical spring component contains, do not account only the error components that such a structure entails, but you are relative the measured value resolution no longer limited by the spring stiffness.

The components of the gravimeter cell are advantageously exposed during the measuring process no deformation, but operated purely static. Changes of component dimensions due to creeping processes or Parameter-changing material recrystallization processes due to mechanical tensile or compressive stresses therefore do not occur.

by virtue of the fact that on the semiconductor chip no mechanical structures have to be generated Its manufacturing process can be entirely based on the optimization of the electronic Circuit components are designed.

Becomes as a dielectric a liquid used, their thermal expansion must be taken into account. Within the molding, for example, a partially gas-filled capillary tube can be provided into which the dielectric fluid can expand into. Due to the surface tension the liquid becomes like the liquid thermometer a hiking of the gas column prevented from the capillary.

at a gaseous one Dielectric is the floating body cavity preferably hermetically sealed, so that at a temperature change the occupied volume of the gas remains constant, and therefore also its density.

There highest to the gravimeter measuring cell Requirements are made with regard to the measuring accuracy, Various error compensation mechanisms are used. It applies especially temperature and aging-related changes in the value of mechanical and electric way to compensate.

to Generation of two mathematically different from the gravitational field and the error components more dependent Readings, can on the chip two identical floating body units in all dimensions be upset. Likewise the associated Control and evaluation circuit parts to be identical.

A difference between the two arrangements is that the float 100 . 200 (please refer 5 ) consist of two different metals with different densities. This ensures that the gravitational field receives two different factors in the measurement results of the two floating body units. Since both factors are known, an error compensation can be carried out by offsetting both measured values.

at Use of a liquid Dielectric, which can be generated by its thermal expansion Buoyancy error to be compensated in this way.

One Comparison of capacity values of the eight electrode segments within a floating body unit provides additional Correction values.

While one position change of the float for one part of the electrodes an increase in capacity, and for another Part of a decrease results thermal material expansion to similar changes. By suitable allocation of the electrode segment values among each other, these errors can be compensated. With the help of another Cavity assembly, which includes no float, it is possible the basic capacity values to measure separately.

By Generation of test forces can be more information about the functional parameters of the measuring cell are obtained. To this Purpose is over the existing electrodes an additional electrostatic Force field in the float coupled. The field control in the electronics is thereby caused to adjust the strength of the existing compensation field to the balance of power in the float to maintain. The force field generation can be done with this method be measured in their characteristic.

By change the float position from the center, due to other setpoint specification for the control, let yourself from the resulting electrode capacitance values at different distances between the float and the individual electrodes, the capacitance-distance characteristic of the measuring cell remeasure.

With This method allows the cell in all three dimensions automatically measured and recalibrated.

A further error correction option is the direct temperature compensation. On the semiconductor chip, a temperature sensor is integrated and according to predetermined value dependencies Compensation executed. Since the entire measuring cell itself only has chip size, a compensation-distorting temperature gradient does not occur.

Of the executed in the complete sensor Billing process of the measured values of the individual gravimeter circuits, leads a similar residual error of the cells, to another compensation effect. The Chips for The measuring cells of a sensor should therefore be the same manufacturing wafer be removed.

If despite all corrective action and the advantageous high degree of integration of the measuring cell, the required Measurement accuracy can not be achieved by using a third floating body with third density value, another set of input values for Accuracy increase can be generated.

A second embodiment of a Schweighörpergravimeteranordnung is in the 3 and 4 shown.

3 shows a cross section through a further embodiment of a gravimeter unit according to the present invention.

4 shows a plan view of a semiconductor chip with electrodes of the in 3 illustrated embodiment of the gravimeter unit.

If the gravimeter cell is always mounted in such a way that the earth's gravitational field points away from the chip surface, then the entire electrode structure on the chip can 101 be applied. The molding 102 then comes out without electrical connections. By means of external electrodes 114 . 214 can be laterally on the float 100 . 200 generate acting forces. The ever-present force component to the chip surface counteracts mounting due to the earth's field.

Since the outer electrodes can produce only small forces, the float can 100 . 200 be advantageously designed as a low-mass flat disc. By combined control of the outer electrodes 114 . 214 and internal electrodes 113 . 213 All required force components can be generated.

The molding 102 can be made both of insulating material as well as metal in this arrangement. When using a metallic molding this is connected to the circuit ground potential and thereby acts simultaneously as an electrical shield for the measuring system. The cell alignment to the earth's surface can deviate by approximately +/- 45 degrees in both spatial directions.

In addition to the described electrostatic forces of attraction, the generation of repulsive forces is also possible. The float 100 . 200 must be made of a non-conductive material such as glass or ceramic for this purpose. Its dielectric constant must be smaller than that of the liquid used. An electric field built up between two electrodes then acts repulsively on the float.

The Combined generation of both types of force is possible by the non-conductive float is provided with a partial metallization. The semiconductor chip becomes thus enabled, with the electrodes on it to attract the metallized part of the float and the non-metallized part repel. It can thus forces be generated in all spatial directions, so that a cell alignment is not required.

While at Application of attractive electrostatic forces control of the electrode voltage is imperative to keep the float stable in the air to hold, when using repulsive forces a force field control not in principle required.

A approach of the float a repulsive one Force field, leads with decreasing distance and thus increasing electric field strength, too an increase in field forces. The float approaches Therefore, the electrodes only so far until gravitational forces and electric field forces keep the balance. From the self-adjusting intervals of the float to the individual electrodes, then can the value of the gravitational field be calculated in the 3 spatial directions. The application of an active field control at repulsive Force fields, however, can still be favorable, as a constant Float position Advantages of error compensation offers.

A third embodiment of a floating body gravimeter arrangement is shown in FIG 5 shown. The molding 102 also requires no electrode structure in this arrangement. It is possible forces of both polarities in all three dimensions on the float 100 . 200 couple.

A difference from the above-described arrangement is that purely metallic floating body can be used. The molding 102 is designed for this purpose basically conductive and connected to ground. By special mechanical shaping, it receives the function of an electrode attracting the float. This is achieved in that the effective electrode surface by attaching the recess 111 . 211 on an annular edge zone 112 . 212 is reduced. This edge zone 112 . 212 has a smaller area than the sum area of the internal electrodes 113 . 213 and external electrodes 114 . 214 on the chip. Be the chip electrodes 113 . 114 . 213 . 214 driven with an identical voltage value, which is different from ground, so there is a higher electrical field density at the ring electrodes 112 . 212 as at the chip electrodes 113 . 114 . 213 . 214 , As a result, the float is attracted to the ring electrode. If the float is to be attracted by the chip electrodes, this is done by using different voltage potentials between the individual chip electrodes.

5 also shows an alternative embodiment for the float 100 . 200 , To increase the electrostatically generated lateral forces, the floating bodies 100 . 200 each over a depression 115 . 215 at its bottom. This creates an annular edge zone 216 the chip electrodes 113 . 114 . 213 . 214 faces. The border zone 216 has an additional inside surface 219 that it's the internal electrodes 113 . 213 also allows side forces to be coupled into the float. The outer electrodes 114 . 214 serves the outside surface 218 the coupling of lateral forces.

It there is also the possibility on the float bottom provide a plurality of concentric ring structures, each having a own assigned set of internal and external electrodes have to even higher lateral forces to be able to produce.

By suitable control of multiple existing electrode segments can the for the force field generation electrically effective electrode surface to test and control purposes.

Farther it is possible to execute the ring structures at different heights, so that every single one Ring over has a different distance to the electrodes on the chip surface. A Such arrangement allows the float position using several times to determine different gap widths. Based on the known Ring height values can be the distance difference distance measurements of Free up existing error components.

This Procedure has opposite a variation of the position setpoint, for the purpose of measuring the capacitance-distance characteristic, the advantage that the float does not have to be moved. The assigned to the individual rings Electrodes also allow the electrical field forces variable over different Coupling gap widths.

8th shows as a fourth embodiment, a gravimeter with a gap-width-structured float 109 which has three ring units a, b, c. The ring units consist of ring structures 116a . 116b . 116c and depressions 115a . 115b . 115c , On the semiconductor chip 101 are annular outer electrodes 114a . 114b . 114c and internal electrodes 113a . 113b . 113c appropriate.

With the use of a gaseous dielectric with a constant density, it is possible with such a design to derive all of the measured values required for error compensation from a single float. The Gravimetermesszelle needed in this case, as in 8th shown, a total of only one Schweungsanordnung.

Becomes a liquid Dielectric used, so its thermal expansion, and the resulting buoyancy error, generally two Floating arrangements for error compensation. Can with the used Dielectric but calculated from the dielectric constant of the density value because, for example, the electrical susceptibility of the dielectric proportional to the density value, so is in this way also the buoyancy error compensation executable.

The determination of the dielectric constant is carried out by offsetting the capacitance values of a sufficient number of electrodes, so that other capacity-determining quantities, such as, for example, the position of the floating body and the basic substrate capacitances, can be eliminated. An arrangement like in 8th shown, has a sufficient number of electrodes for this purpose.

at Use square instead of round float, are the aforementioned ring structures correspondingly identical by polygon-like structural geometries to replace.

electrical conductive float or molded parts can in addition to metal also alternatively made of metallized insulating material, such as Glass or ceramics. Contour-accurate production metallic float or metallic moldings can by stamping forming suitable blanks respectively. Glass-based parts can be precisely shaped by pressing in the plastic hot state.

Next solid floating bodies can in principle also liquid balls be used. The dielectric may be either gaseous, or consist of a non-mixing second liquid. Likewise is the use of an electrostatically levitated gas bubble in a liquid conceivable. The small size. strongly increasing surface tension takes care of a defined form of these floating objects.

It there is also the possibility the float completely from one, all electrodes bearing, molding assembly surrounded, and the semiconductor chip or other electronics with conductor connections to dock. It is also possible the float sandwiched between two semiconductor chips. Farther it is possible the wells for the float not to be provided in the molded part but on the semiconductor chip itself.

9 shows in this regard, a fifth embodiment of a Schwebstörpergravimeters, wherein for the sake of simplicity, only a floating arrangement is shown. Inside two, at a dividing line 93 superimposed moldings 91 . 92 , which each have a hemispherical recess 10 , there is a spherical float 100 , Each of the moldings 91 . 92 carries in his recess 10 For example, four electrodes of quarter spherical cap shape, to force-generating and distance-measuring electric fields on the floating ball 100 to be able to couple. Of the 4 electrodes per molding, are in 9 only two electrodes each 5 . 8th respectively 6 . 7 to see. reference numeral 94 denotes an electrode extension limit. reference numeral 95 denotes an insulation gap.

The spherical shape of the float 100 allows a simplified field control, since due to the rotational symmetry of the spherical body with respect to all three spatial axes, can be dispensed with the regulation of all three rotational degrees of freedom, and therefore only the remaining three translational degrees of freedom are to be regulated.

As both moldings 91 . 92 are generally passive in nature, and therefore must be connected by means of stray-capacitive conductor connections to an external electronics, Schweungsanordnungen are particularly advantageous with elektrodentragendem semiconductor chip.

in the Schwebekörpergravimeter are preferably electric fields for power generation and distance measurement used. These can be generated with minimal energy consumption, just shield and the needed Electrode arrangements are inexpensive and very precise to produce as well as integratable.

alternative can also magnetic fields are used. The float is surrounded by electromagnetic coils. One made of ferromagnetic Material, such as iron or ferrite ceramic, existing float is attracted by the magnetic field of the coils. Body made of permanent magnetic material can be tightened as well as depending on the field polarity of the coils repel. body nonmagnetic but electrically conductive material, such as Aluminum, can due to eddy current formation by alternating magnetic fields of Coils, repelled by these become.

Also the distance measurement can be done by means of magnetic fields. Out the inductance values of the Coils, as well as from the magnetic coupling between the coils, the distance to a ferromagnetic float can be determined become. In an ohmic conductive Body, can the distance measurement by evaluation of the resistive component the AC impedance of the coils take place. From the float outgoing Fields, or changed by him Field amplitudes also represent a measure of the distance. The field strength measurement For example, by means of magnetoresistive, Hall or GMR sensor elements happen.

at Application of magnetic methods is sufficient shielding opposite the measuring cell Provide ambient magnetic fields.

The Float position can also be determined conductively. This is an ohmic conductive dielectric to use. The then occurring resistance value between individual Conductive measuring electrodes, provides a measure of the float distance to the electrodes. Is a not too low-resistance dielectric used, so is a simultaneous resistive and capacitive distance measurement feasible. As well the possibility remains obtained the electric power field generation.

Of Furthermore, an optical distance measurement is possible. These For example, by evaluating the shading effect of float on a light beam, by measuring the amplitude of backscattered from the body Light of a point light source and interferometry done.

in principle there is also the possibility by mechanical means, for example by arrival or flow around the float by means a fluid which occurs in place of the dielectric, or this can represent themselves, forces on the float coupled, and from the gap-width-dependent flow resistance of the arrangement, Conclusions on the body position to draw.

to suppression of the disturbing Influence of ambient vibrations on the gravimeter output signal There are different possibilities.

It is advantageous to embed the measuring cell carrier in insulation, or with other measures the vibration transmission from the sensor housing to inhibit the measuring cells.

Of Further, when using a liquid dielectric, the flow-related fluid friction for vibration suppression exploited become.

at Measuring cells with gaseous Dielectric can by appropriate design of float and Molded part also a vibration damping by the dielectric be effected.

Of the float is done this way, that it moves as possible in each of the three spatial directions, one as possible size volume displacement the gas dielectric causes, but at the same time only a minimal Own weight.

The float 100 can be cup-shaped, hat-shaped or semi-closed cylindrical constructed for this purpose as in 8th shown, as well as versions are possible as a completely closed hollow body. The displaced gas volume during movements must flow through the narrow gap between float and molded part to the opposite side, so that only slow movements are possible.

at metallic floating bodies can alternatively also eddy currents for vibration damping be used. For this purpose, a permanent magnet is on the molding attached, which the electrically conductive float a inhomogeneous magnetic field exposes. Every movement of the float leads to Formation of eddy currents, their own magnetic fields according to Lenz's law of causing them Counteract movement.

It there is also the possibility vibratory forces Compensate in real time by electrostatic forces of the electrodes. Because mechanical vibrations usually occur in the frequency range from 1 to 1000 Hz, the regulation of electrostatic fields but with frequencies of several hundred MHz, the electrical compensation forces are more than five Powers of ten faster than the highest mechanical vibration frequencies.

There Vibrations represent a pure variable of change, the gravitational field, however, is a DC field size, can by vibration suppression and Measured value integration the desired Separation brought about become.

By the extensive diagnostic functions in the context of the error correction, puts the float gravimeter cell a self-monitored Measuring system. The sensor operator receives a reliable fault message in case of failure, Similarly, if the parameter deterioration is a fallback signal than Warning message can be issued.

by virtue of the minuteness of the measuring cells, is for special safety requirements also the construction completely redundant sensors possible, without the outside dimensions enlarge. A mutual influence of the measuring cells or complete sensors does not occur due to the principle.

By Arrangement of numerous measuring cells in the form of a matrix, too the realization of imaging sensors conceivable.

The Float Gravimeter according to the invention and the gravitational field evaluation methods described above may be used alongside the use in level sensors also for other applications of qualitative and quantitative detection be used advantageously by masses or their volume. It can with only one type of gravimeter circuit, all kinds of measurement applications be covered because the earth's gravity field in all cases always representing the dominant size.

Of Further is the float measuring cell according to the invention in addition to the detection of gravitational acceleration also for measurement can be used by accelerators of other types. Opposite known Acceleration sensors, it has especially in the measurement very small acceleration values advantages. She lets herself therefore, for example, in inertial navigation systems for vehicles, Submarines and missiles use of various kinds.

Complementary to point out that "comprising" no other elements or excludes steps and "one" or "one" does not exclude a multitude. Further It should be noted that features or steps with reference to one of the above embodiments have been described, also in combination with other features or steps of other embodiments described above can. Reference signs in the claims are not as a limitation to watch.

Claims (34)

Gravimeter unit for determining a gravitational field strength, the Gravimeter unit comprising: a first float; one first detector; a source for generating a field; in which the first float is non-contact in suspension by a field generated by the source; in which a first position of the first float through the first detector is detectable; wherein the gravimeter unit is executed, first data based on the detected first position or the generated Field to determine; and the first data being a first Gravitational field strength correspond at a first location. The gravimeter unit of claim 1, wherein the field selected is from the group consisting of electric field, magnetic Field, electromagnetic field and mechanical flow field. Gravimeter unit according to one of claims 1 or 2, wherein the first detector for capacitive, inductive, conductive or optical detection of the first position of the first float is performed. Gravimeter unit according to one of claims 1 to 3, wherein the source comprises at least a first electrode, to Generation of the electric field; and wherein the first detector a second electrode for detecting the first position of the first float. Gravimeter unit according to claim 4, wherein the float in one filled with a dielectric Cavity is arranged. Gravimeter unit according to one of claims 1 to 5, further comprising: a second float; one second detector; wherein a second position of the second float by the second detector is detectable; and the gravimeter unit accomplished is the first data based on the measured first position and the to generate measured second position. A gravimeter unit according to any one of claims 1 to 6, further comprising: a controller; wherein the control device is designed to hold the first float in an initial position. Gravimeter unit according to claim 7, the Control device one strength of the field generated by the source based on that of the first Detector detects the detected first position of the first float, so that the first float in the home position is held; and the gravimeter unit accomplished is the first data based on a control parameter of To produce control device. Gravimeter unit according to one of claims 1 to 8, further comprising: a memory device; in which the memory device is designed to store reference values. Gravimeter unit according to one of claims 1 to 9, wherein the gravimeter unit is formed on a semiconductor chip is. Sensor for material detection by means of a gravitational field evaluation, the sensor comprises: a first gravimeter unit after a the claims 1 to 10; a second gravimeter unit according to one of claims 1 to 10; a communication interface; the first one Gravimeter unit for determining first data, which with a first Gravitational field strength correspond to a first location is executed; the second one Gravimeter unit for determining second data, which with a second gravitational field strength correspond at a second location is executed; and the Communication interface for transmission the first data and the second data is executed to an evaluation unit. Sensor according to claim 11, where the determined first data on first float position data or first control parameters of a first control device based; and wherein the determined second data on second Float position data or to second control parameters of a second control device based. A sensor according to claim 11 or 12, wherein the first and the second gravimeter unit relative to each other at fixed positions are arranged in the sensor. Sensor according to one of claims 11 to 13, the first gravimeter unit rotatable about an axis or along a is arranged displaceable common axis; the first one Gravimeter unit during a rotation or displacement to measure a first volume data set, which comprises the first data is executed. Sensor according to one of claims 11 to 14, further comprising: in which the sensor next to the first and second gravimeter unit a Comprises a plurality of third gravimeter units, which together with the first and the second gravimeter unit a one-, two- or three-dimensional array for measuring a line, area or Train volume data set. A sensor according to any one of claims 11 to 15, further comprising: a evaluation unit; wherein the evaluation unit for receiving the first data and the second data from the communication interface accomplished is; and wherein the evaluation unit for calculating a gradient a gravitational field based on the first data and the second Data executed is. Sensor according to claim 16, wherein the evaluation unit to calculate a local Mass distribution is carried out in the vicinity of the sensor. Sensor according to claim 16 or 17, wherein the evaluation unit to calculate a level a container based on the first data and the second data. Sensor according to one of claims 11 to 18, wherein the sensor is formed on a semiconductor chip. Method for level measurement a filling material in a container by means of a gravitational field evaluation, comprising the method the following steps: Determining first dates which correspond to a first gravitational field strength at a first location, by a first gravimeter unit; Determining second data, which correspond to a second gravitational field strength at a second location, by a second gravimeter unit; Calculate a level of the contents based on the determined first and second data. The method of claim 20, further comprising the steps: Generating a field by a source; detect a first position of a first float of the first gravimeter unit through a first detector; wherein the first float through a field generated by the source is held in suspension without contact becomes; and wherein the first data based on the detected first position or the generated field. The method of claim 20 or 21, wherein the field selected is from the group consisting of electric field, magnetic Field, electromagnetic field and mechanical flow field. The method of any of claims 20 to 22, wherein the first Detector for capacitive, inductive, conductive or optical Detection of the first position of the first float is carried out. Method according to one of claims 20 to 23, wherein the calculation the level calculating a gradient of a gravitational field in the area of the contents based on the first data and the second data. A method according to any one of claims 20 to 24, wherein the first and the second gravimeter unit relative to each other at fixed positions are arranged in a sensor. The method of any of claims 20 to 25, further comprising the step: Rotate the first gravimeter unit by one Axis or moving the first gravimeter unit along a Axis; wherein the first gravimeter unit during a rotation or displacement for measuring a first volume data set, which is the first Includes data, executed is. The method of any one of claims 20 to 26, further comprising the step: transmission the first data and the second data through a communication interface to an evaluation unit. Use of a sensor according to one of claims 11 to 19 as a level gauge. Use of a sensor according to one of claims 11 to 19 as a proximity sensor. Using a gravimeter as a level gauge. Using a gravimeter as a proximity sensor. Use of a gravimeter unit according to one of claims 1 to 10 as an accelerometer. Program element for level measurement of a filling material in a container by means of a gravitational field evaluation, wherein the program element, when running on a processor that instructs processor, to perform the following operations: Determine of first data, which with a first gravitational field strength at a first place correspond by a first gravimeter unit; Determine of second data, which with a second gravitational field strength at a second place correspond, by a second gravimeter unit; To calculate a level of the contents based on the determined first and second data. A computer-readable storage medium on which a Computer program for level measurement a filling material in a container is stored by means of a gravitational field evaluation, wherein the computer program when it runs on a processor instruct the processor to perform the following operations: Determine of first data, which with a first gravitational field strength at a first place correspond by a first gravimeter unit; Determine of second data, which with a second gravitational field strength at a second place correspond, by a second gravimeter unit; To calculate a level of the contents based on the determined first and second data.