DE4313418A1 - Method and device for the digital determination and remote interrogation of filling levels and levels in liquids or media of limited high viscosity, using discrete sensor positions - Google Patents

Abstract

Methods and devices are used for the detection and remote interrogation of filling levels and levels, whereby in contrast with the prior art used, with almost exclusive utilisation of analogue (continuous) sampling, the procedure here uses digital methods, with closely-spaced discrete sensor positions, so that the errors associated with analogue methods are eliminated. For Claims 1 to 3, an electrical conductivity is presupposed in the case of the media. Main Claim 1 covers in general the detection of the liquid level by causing a potential state on pick-up contacts, while Subclaim 2 makes use of control as a function of the liquid conductivity. Main Claim 3 describes bringing about a defined sensor state as a function of the liquid level by means of an electrical displacement current between capacitor plates. The following claims from 4 onwards relate to (active or passive) sensor-controlling elements which are coupled (in a floating manner) to the upper limit of the liquid or of a more highly viscous medium and influence pick-ups adjoining it. In so doing, various physical principles are used which are assigned in each case to the individual claims.

Description

Almost all physical levels can be used to determine the level of a liquid Principle of measurement and for this all several sub-methods are used. they However, with a few exceptions (cf. Refs. 1 and 2), they are based on an analog recording the mirror position (e.g. with pressure sensor lying on the liquid floor, with ultrasound measurements for the path from the top to the top edge of the liquid) with all the known deficiencies in analog technology. Or they are based on singular sensors Threshold detection or on the information jump of a single sensor, the is lowered mechanically or manually from above and when in contact with the liquid a reaction can be seen, while the depth as a vertical advance of the lowered sensor is detectable. The traditional slat levels, for example, are not automated and require the optical detection by the observer. A Automation of the various manual measuring methods with a lowering one Sensor and individual observation of the mirror indication would be unrealistic.

So there is a need to create fully automatic registrable arrangements from one to provide chain-like plurality of equally spaced individual sensor elements, the each state relative to the liquid level (above and below) through the The measuring principle used is clearly digitally recognized and by suitable circuitry Precautions can be made remotely, the accuracy of the detection Given by the vertical distance from the individual sensor element to the next is, theoretically, can be made arbitrarily small and where the depth of the mirror results from the serial number of the sensor that is responsible for the information jump serial detection electronically.

The interrogation takes place as a digital recording of the states L and H of the individual sensors and excludes a large number of the errors known from analog sensors (none Aging, no TC, no air pressure dependency, no hysteresis etc.) and also has as The advantage is the direct and primary provision of digital data for simultaneous storage of measured values without the need for an A / D conversion, which in turn causes errors.

Such arrangements can consist of many hundreds of individual parts, the possibility of cascading is almost unlimited, which also means that which is otherwise customary for analog processes Specification of the relative error becomes obsolete, which is particularly evident in digital measuring devices a long length after being replaced by the constant absolute and then many smaller measurement uncertainties make the advantage recognizable.

The invention essentially consists in being reproducible point by point reliably queryable information of this "electronic staff level", which is also fully system-compatible be designed, provided with a data logger and also for any Time can be prompted to output information manually. In addition, is still in In principle, in contrast to analogue devices, there is a possibility of self-checking for that Given overall system.

The function of the measured value recordings according to the inventive idea will be shown with the aid of three examples. Fig. 1 may be, inter alia, for explaining claim 1 are used, Fig. 2 explains the claims 3 and Fig. 3 one of the claims from Nr. 4,.

To Fig. 1

Here is 1 horizontally arranged pair of metallic for each sensor element Contact points exist that are only electrically below the level above the liquid  is connected. In the drawing, G are the potential-changing current transmitters, that affect the transducer contacts A. On the board P is the electronics that can distinguish between the two states "wetted" and "unwetted". On electrical command from above - usually with an adjustable time interval - is then the one Boundary line queried digitally, which corresponds to the liquid level. The data can be in any given rhythm or at any time by Manual selection can be queried and saved.

To Fig. 2

The capacitive determination of the height of the water level ( 5 ) by detection of the displacement current through an insulating layer ( 1 ), z. B. can be put through a tube, due to, for example, a conductive feed of an alternating current through the electrode ( 3 ) and generated by the generator ( 4 ), with reference to the capacitor rings ( 2 ), by comparing the capacitor ring potentials with one Reference potential, such that the individual information obtained can be digitally evaluated and remotely queried at each sensor.

To Fig. 3

Here a floating body (K) moves with the fluctuations in the liquid level and passes the sensors (S) on the side, which are close to K in their state (L or H) can be changed and when queried electronically from above provide the information related to the depth (serial number).

Literature references

L. 1 BUSCH, K.-F. & LUCKNER, L. (1972). Geohydraulics. VEB German publisher for Basic industry, Leipzig.

L. 2 RAMMNER, R. (2.7.1992). Method and device for determining fill level and levels in electrically conductive liquids using discrete sensor positions. German Patent office, disclosure DE 40 42 257.

Claims (10)

1. A method and devices for determining fill levels and levels of electrically conductive liquids using a variety of arranged along a non-conductive support body sensors each with metallic (or other) electrically conductive) contacts of the ability to absorb electrical potentials, characterized in that by further Potential-carrying contact points located at the same height on the carrier body or arranged lower then the first-mentioned transducer contacts experience an electrical potential impression by flowing an electric current in the liquid as soon as they are below the liquid level, in contrast to the transducer contacts located above the level. so that the electronic processing of the influence of the transducer contacts enables a clear differentiation of the wetting state and can also be remotely queried. 2. Method and device for determining fill levels and level heights according to 2., characterized in that in addition a regulation of an (otherwise dependent on conductivity) Potential imprint depending on the conductivity of the liquid and that this is done by controlling one of the lowest points of the column to be queried arranged and on a suitable circuit of the electronic components between Potential sensor and potential sensor acting conductivity sensor is guaranteed or that these are each on the individual element by means of potential-carrying contact points in the immediate (no higher) environment of the individual sensor by a suitable electronic circuit between the current-emitting primary potential-carrying Contact point and the potential sensor contact automatically by the Current path resistance in the liquid between the two takes place by this the potential of the transducer contact also defined. 3. A method and apparatus for determining fill levels and level levels of electrically conductive liquids using a variety of sensors arranged lengthways in an insulating material sheath, characterized in that a small capacitor plate separated from the liquid by means of the insulating material sheath undergoes a potential change in each sensor element, in that the surrounding liquid column receives a quasi-uniform alternating voltage potential, thus represents the counterplate for all small internal capacitor plates and, due to the AC voltage supply, causes a displacement current to flow through all the elements up to the upper end of the liquid column to the individual plates can, by means of the resulting potential changes in the capacitor plates, the individual sensor elements in their state (except wetted or not wetted) t and can be queried remotely.
Claims 4 to 10.
Method and devices for determining fill levels and level heights of liquids or generally of media with limited high viscosity, characterized in that using a variety of sensors, fixedly arranged along a carrier body, of sensors and / or receivers at discrete positions, these are then identified by a sensor on the upper edge the floating medium, which is floating in parallel, can be influenced, if the active or passive body is buoyant, if it is at its height, this changes its state (L or H) and the sensors can be digitally queried and localized due to suitable electronic precautions and moreover; 4. The running body consists of a magnet and on reed relays or otherwise magnetostatically influenceable sensors acts; 5. the running body for any electromagnetic waves a reflector or Represents absorber and acts on (optically) sensitive sensors in this regard; 6. the running body for sound or absorber represents and acts on acoustically sensitive sensors;   7. The running body due to its heat capacity or thermal conductivity on the Temperature, the heat flow, the heat flow or the heat radiation thermal sensitive sensors acts; 8. the running body due to its properties in terms of Dielectric constant, permeability or electrical conductivity a capacitive or inductive detuning or other influencing of sensors with C or L containing Assemblies obtained; 9. the running body through parts of the sensors electrostatic or electromagnetic can be changed and thereby retroactive to electrostatic or electromagnetic sensitive other parts of the sensors changes state; 10. The running body by means of elastic (metal) springs mounted on two contacts of the sensors that are isolated from one another are located directly with one another connects or ensures contacting through its own conductivity or one Contacting via a thin interlayer of liquid is due to its intrinsic conductivity enables and hereby affects the digital state of the sensors.