DE10201769A1 - Level sensor has a simple optoelectronic detector arrangement that can be used with containers of varying size and liquid or material products and is suitable for indicating the presence or absence of a given amount of product - Google Patents

Abstract

Level sensor for detecting the presence or absence of a liquid or material within a container (3) with a liquid or material level sensor comprising a transmitter (1) and receiver (2) for detection of radiation transmitted by the transmitter. The wall of the container (8) is at least partially transparent and sloping in the area of the transmitted beam. As the wall of the container is sloping when the transmitted beam is incident on it, the transmitted beam will only reach the detector when the container is empty and the beam is not diffracted away by liquid or absorbed by solid material.

Description

The invention relates to a level sensor for determination a level of a substance in a container after Preamble of claim 1.

Level sensors are often attached to containers z. B. reaching a certain level or Falling below a fill level below a predetermined level Minimum threshold and, if necessary, the need for Signal to fill the container.

So far, for example, fill level sensors are known a transmitter and a receiver for transmission or Receive radiation include. In general, the Radiation from the transmitter through the interior of the container to Receiver. A suitable container can, if necessary either with a liquid or a solid substance, the is as impermeable as possible to the radiation by the user or consumers are filled. Is the container like this filled that the level of the operating material is above of the sensor, the radiation hits in the area of the Entry area on the operating fluid and is from this absorbed or reflected. As a result, the recipient receives preferably no or a relatively low radiation, thereby advantageously a corresponding signal is generated, the level by means of an evaluation unit or the presence of the substance signals. The Receiving or not receiving the radiation used accordingly for signaling.

A disadvantage of a level sensor with a transmitter and a receiver for radiation according to the prior art is that this is for radiation only absorbent or reflective materials is suitable.

In contrast, the object of the invention is a Level sensor for determining a level of a Substance in a container with at least one transmitter for Sending radiation and a receiver for receiving the emitted radiation, the container at least one that is at least partially transparent to the radiation Wall section includes and the beam path from the transmitter to Receiver runs through the interior of the container, propose where the scope is essential is expanded.

This task is based on a level sensor type mentioned in the introduction, by the characteristic features of claim 1 solved.

By the measures mentioned in the subclaims advantageous embodiments and developments of the invention possible.

Accordingly, one according to the invention is distinguished Level sensor characterized in that the wall section at least one at an angle to the beam direction, in particular arranged on the inside of the container, Interface includes.

With the help of a trained according to the invention Level sensors can, on the one hand, fill liquid or solid fuels are determined that the radiation absorb and / or reflect. On the other hand, in advantageously by means of the level sensor according to the Invention additionally the level or the presence of especially liquid, largely for radiation permeable consumables can be detected.

According to the invention, an optical refraction or Redirection of the beam path to the beam direction oblique interface due to the generally different refractive index of air or of the liquid substance allows. In addition, detection of gaseous fuels with air different refractive index possible.

It is advantageously provided that the Angle of incidence of the radiation with respect to the oblique angle Interface larger than that of the refractive indices of the media dependent critical angle of total reflection is.

Advantageously, according to the invention for Determining the fill levels of several containers independently on the state of matter and / or on the refractive indices of the Detecting substances several, almost identical Level sensors used in a single machine become. This leads in particular to comparatively high ones Production numbers of a correspondingly versatile Level sensor, so that the manufacturing cost compared to special level sensors with relatively low Reduce the number of pieces according to the state of the art can.

In a special development of the invention, the oblique interface is the entrance surface of the radiation in the container. This results in an advantageous manner due to the between the interface and receiver located interior of the container a large distance between the radiation refractive interface and the Receiver, so that a comparatively small deflection of the Radiation at the interface, e.g. B. due to a relative small difference in the refractive indices of air and the liquid fuel, to a relatively large, cross-directional or lateral deviation in the Area of the recipient. In particular, this enables that the radiation is relative in an advantageous manner is directed far past the receiver. For example hereby achieved that due to the optical refraction of the Radiation as little as possible or none under certain circumstances existing scattered radiation is perceptible by the receiver.

The transmitter may be on one side of the container and the receiver on an opposite side Side of the container arranged. For example, transmitters or receiver plane-parallel on the container wall and / or be arranged at an angle to the container wall.

In a special variant of the invention, the Arrangement of the entry and exit surface of the A prism, a lens or an optical grating out.

The beam path advantageously runs through a intended form of the container, in particular Bulge, bulge or the like. Appropriate Formations are comparatively easy to produce.

If necessary, the shape is formed such that in Depending on the level of the substance to be detected The radiation is reflected or not reflected on it, so that the receiver receives the radiation or not receives. Here are the sender and the receiver optionally arranged side by side.

The formation may be designed in such a way that preferably standard components, such as. B. commercially available Transmitter, receiver or light barriers or the like, can be advantageously arranged on the formation.

The beam path preferably runs through a provided corner area of the container. Often point corresponding containers already have an essentially angular, in particular a square cross-section, so that the Level sensor according to the invention already without change existing container shapes can be arranged on them. This enables an economically advantageous implementation of the Invention. In addition, according to the invention Variant if necessary, an advantageous retrofit to already existing containers can be realized with little effort.

The wall section of the container can according to the invention both an almost constant wall thickness and one itself changing wall thickness in the entrance or exit area of radiation. It is conceivable that the Beam path through a recess or Cavity of the container wall runs.

Advantageously, at least two sections of the Formation at an angle, in particular almost 90 degrees, arranged to each other. This is advantageous Dimensioning of radiation that can be crossed out Container interior possible.

In general, the entry and exit area of the Container as a coherent, for radiation at least partially permeable wall section or from at least two separate wall sections can be realized. The container is preferably essentially made of a the radiation is at least partially transparent material educated. In the latter training of Invention is a particularly flexible arrangement of the Level sensor can be implemented on the container.

In an advantageous variant of the invention, the Radiation a predetermined, relatively narrow Wavelength range. This will be more advantageous Way a defined refraction or deflection of the radiation achieved according to the invention.

The transmitter or receiver can, for example, transmit or Receiving radiation in the visible as well as in the ultraviolet wavelength range are formed.

The receiver or the transmitter are advantageously used for Sending or receiving infrared radiation trained. A corresponding fill level sensor is advantageous Wise to interference from daylight comparatively insensitive. For example, the transmitter as an infrared diode and the receiver as a corresponding photo Transistor are formed. Preferably for the Sender and / or the receiver already commercially available Standard components used.

The transmitter can advantageously be used intermittently or are operated temporarily and / or clocked. hereby can cause interference from outside light as well as energy requirements be significantly reduced.

The beam path advantageously runs during the Measurement phase in an almost horizontal plane. This is an advantageous arrangement in the area of a largely vertical longitudinal edge of the container can be realized.

For example, the level sensor is close to one vertical longitudinal groove and / or a corresponding corner area arranged of the container. Alternatively, the Beam path during the measurement phase in an almost vertical Level. In certain applications, the Corresponding sensor on the horizontal longitudinal edges of the container to be ordered.

Generally, a sensor can be switched on by means of a control unit Signal, especially for a user or consumer generates the non-existence of the substance or the Signals the presence of preferably air in the container, additionally in an advantageous manner in the absence generate a corresponding signal from the container. According to the Invention can be a level sensor for determining the Level of a substance in the container and in addition to Determined the presence of the container become. This advantageous variant of the invention is before especially if you have to remove or exchangeable containers can be used advantageously.

In a special development of the invention Evaluation unit for the quantitative evaluation of the Receiver detected radiation or amount of radiation intended. This can be used in an advantageous manner Contamination of the container and / or a quantitative one Determines the parameters of the substance and if necessary be signaled. For example, the need to cleaning the container are displayed advantageously.

In an advantageous variant of the invention, the transmitter and the receiver in parallel in the same circuit with two Connections switched, one controlled by the receiver Electronic component is provided, which is the voltage and / or the current between the two connections affected. With such a circuit arrangement fill level sensor according to the invention, the number of necessary connections to the corresponding control unit reduce two connections, reducing the wiring effort both in terms of material and assembly is reduced.

In many possible applications for corresponding sensors there is enormous cost pressure, so that too Connection and wiring a not inconsiderable effort represents. Often these are devices with high Quantity, so that small savings with the help this variant of the invention noticeably to reduce costs contribute.

The measurement signal can be that in the energized state of the sensor voltage present between the connections or in Circuit flowing current can be evaluated. The recipient such a sensor arrangement can be, for example Resistance dependent on the measured variable, a dependent on the measured variable Capacitance and / or an inductance dependent on the measured variable his.

In a further advantageous embodiment, a Control device provided that works in cyclical operation.

On the one hand, this allows the total electricity demand Sensor device including control unit clearly lower, resulting in a lower performance and thus cheaper power supply can be used.

In addition, the use of several is in one cycle Sensors with circuit according to the invention by the same Control unit possible by alternating the individual sensors be queried for the state of their transmission link. In a special embodiment, a So-called multiplexer between the control unit and the various sensors arranged.

In conjunction with one of the above Embodiments in which a capacitor in Receiver circuit is arranged, is also in cycle mode particularly simple voltage evaluation possible by the Voltage curve at the two connections after termination a voltage or current pulse through the control unit is recorded and evaluated. Depending on the state of charge Capacity results in a different time course of this Tension.

Furthermore, the cycle operation results in a permanent one Resetting the sensor circuit to its initial state, see above that gain effects or oscillations caused by the Influencing the transmitter power through the parallel in receiver located in the same circuit, cannot have any adverse effects.

An embodiment of the invention is in the drawing shown and will be explained in more detail below with reference to the figures explained.

In detail shows:

Fig. 1 is a schematic plan view of a sensor assembly according to the invention with a level below the sensor,

Fig. 2 is a schematic plan view of the sensor assembly with a level of liquid above the sensor,

Fig. 3 is a schematic plan view of a section of a container wall with a thickened portion,

Fig. 4 is a schematic top view of another sensor arrangement according to the invention with a level below the sensor,

Fig. 5 is a schematic plan view of the sensor assembly of FIG. 4 with a level of liquid above the sensor,

Fig. 6 is a schematic plan view of the sensor assembly of FIG. 4 with a level of a powder above the sensor,

Fig. 7 is a schematic plan view of a further inventive sensor arrangement with a level below the sensor and

Fig. 8 shows a schematic plan view of a fourth sensor arrangement according to the invention in a corner region of a container with a level below the sensor.

In Fig. 1, a level sensor with a transmitter 1 and a receiver 2 is arranged on a container 3 . The transmitter 1 is designed in particular as an IR diode, so that it emits IR radiation 4 , which can be detected by the receiver 2 , which is designed as a corresponding phototransistor.

The container 3 is made according to FIG. 1 essentially from a material that is largely transparent to the IR radiation 4 , for. B. by means of injection molding, deep-drawing or comparable processes. The material of the container 3 has a refractive index n> 1, so that the radiation 4 is optically refracted on the outer and on the inner surfaces of the container 3 and the radiation 4 inside the container 3 is offset somewhat parallel to the outside of the container 3 extending radiation 4 .

When using a container material with a refractive index n of approximately 1, the radiation 4 according to FIG. 4 runs almost straight from the transmitter 1 through the wall of the container 3 and through its interior to the receiver 2 .

A “lightning” symbol each represents the detection of radiation 4 by the receiver 2 . According to the top view of FIGS. 1 and 4, there is a fill level of a fuel, not shown, below the sensor arrangement, so that the container interior between the transmitter 1 and the receiver 2 is preferably filled with air. In this case, for example, the fill level sensor generates an electrical or optical and / or acoustic signal, which may be perceived by a user or service personnel and / or an almost automatic filling device of the container 3 . This accordingly makes it clear that the operating fluid in the container 3 has to be refilled.

Alternatively and / or in combination, the signal can be made available to an automatic filling device. In this case, the operating material is conveyed from a supply line with a controllable valve or from a comparatively large second container (not shown in more detail) by means of a pump or the like into the container 3 , which may be small by comparison. A level sensor according to the invention may also be arranged on the comparatively large container (not shown in more detail), especially for determining a minimum level.

To determine a predetermined maximum fill level, a fill level sensor according to the invention can be arranged in the upper region of the container 3 . For example, a corresponding evaluation unit is designed such that, in the event that the receiver 2 of the sensor receives the radiation 4 , it does not generate an electrical or optical and / or acoustic warning signal for the user or for a loading device.

In FIGS. 2 and 5 the situation is shown in which a liquid 5, z. B. water, at least up to the level of the almost horizontally arranged level sensor in the container 3 .

The liquid 5 according to FIG. 2 has a refractive index n which is not equal to the refractive index of air and almost the same as the refractive index of the container material, so that the radiation 4, for example at an interface 6 at an angle to the beam direction and arranged on the outside of the container. B. is optically broken in the manner shown in FIG. 2. As a result, the radiation 4 is deflected such that it cannot be received by the receiver 2 . The presence of the operating material or the liquid 5 between the transmitter 1 and the receiver 2 can be correspondingly detected, as a result of which the user or a filling device that may be provided is generally signaled that the container 3 is sufficiently filled with the operating material or the liquid 5 .

The level sensor shown works on the principle of optical refraction, so that almost transparent or radiation-permeable liquids 5 can be detected. In addition, operating fluids absorbing or reflecting radiation 4 can also be detected with the aid of a fill level sensor according to the invention. In the case of appropriately designed liquids 5 , both the optical refraction and the optical absorption or reflection of the radiation 4 can be used to determine the fill level.

The liquid 5 according to FIG. 5 has a refractive index n which is not equal to the refractive indices of air or of the container material, so that in this case the radiation 4, for example, at an interface 6 arranged at an angle to the beam direction on the inside of the container. B. is optically broken in the manner shown in FIG. 4. As a result, the radiation 4 is again deflected in such a way that it cannot be received by the receiver 2 . The presence of the operating material or the liquid 5 is again detected accordingly.

Further, according to Fig. 6 and solids such as powder 7, pellets, granules, tablets or the like are detected. Such substances 7 or mixtures of substances are generally detected on the basis of the optical absorption and / or reflection of the radiation 4 according to the invention.

By way of example in FIGS. 1, 2, 4 to 6 shown a nearly rectangular protrusion 8, so that the oblique angle is arranged for radiation 4 interface 6 in a particularly simple manner is implemented. The oblique-angled boundary surface 6 enables the liquid 5 to be detected with the aid of optical refraction, so that, as stated above, both solid and liquid consumables 5 , 7, which in particular are largely transparent to the radiation, can be detected.

In Fig. 3a, a section of a container wall with a thickened portion 11 with the to the beam direction (indicated by double arrow P) oblique boundary surface 6 is shown in each b. Here, FIG 3a and 3b shows by way of example. Two different Strahleinfalls- or beam loss variants. The thickening 11 may be designed as a separate element arranged on an almost plane-parallel wall of the container 3 .

In Fig. 7 a further level sensor assembly is shown in accordance with the invention. Here, the bulge 8 has a wall 9 arranged at an angle to the beam direction with the interface 6 and a wall 10 arranged almost perpendicular to the beam direction. Fig. 7 shows the case is that the level of the operating fluid is below the sensor assembly such that the radiation 4 is received by the receiver 2. With regard to this fill level sensor arrangement, the situation that the fill level of the operating material is above the sensor arrangement is comparable to FIGS. 2, 5 and 6.

In FIG. 8, a fourth level sensor assembly is shown according to the invention, the transmitter 1 and the receiver is disposed at a corner portion of the container 3 2. This represents a variant of the invention that is particularly easy to implement, since the interface 6 , which is to be provided in particular for optical refraction and is arranged at an angle to the beam direction, is realized by means of an advantageous arrangement of the transmitter 1 or receiver 2 . This variant can be used, among other things, for retrofitting existing, generally angular containers 3 .

In addition to the embodiments of the invention shown in FIGS. 1 to 8, wherein the transmitter 1 and the receiver 2 are arranged on an almost horizontal plane, an arrangement which is oblique or almost vertical with respect to the horizontal plane can alternatively also be realized.

In addition, in particular in the case of comparatively large containers 3, it is possible to use a plurality of fill level sensors, preferably arranged one above the other, for detecting different fill levels of the operating material 5 , 7 .

The fill level sensor or the transmitter 1 and the receiver 2 are preferably arranged completely outside of the container 3 , so that a comparatively simple assembly or repair of the fill level sensor can be implemented and possible impairment due to chemically reactive substances 5 , 7 is effectively prevented.

In special applications, the receiver 2 in particular can alternatively be arranged inside the container 3 . Furthermore, if necessary, an extension of the beam path by means of a reflector arranged inside the container and / or outside the container can be advantageous for deflecting the radiation 4 . Since this allows the deviation of the optically refracted from the non-refracted radiation 4 in the region of the receiver 2 to be significantly increased, the sensitivity of the fill level sensor according to the invention is decisively improved.

To determine the fill level of liquids 5 based on the optical refraction, the fill level sensor can in principle also be designed such that the receiver 2 receives the radiation 4 optically refracted by means of the liquid 5 . In particular, the interface 6 is advantageously to be aligned here. In this variant according to the invention, the receiver 2 cannot receive the unbroken radiation 4 .

Furthermore, it is conceivable that, due to the dependence of the refractive index n on qualitative material parameters of liquids 5, the fill level sensor can optionally also be designed as a sensor for determining a specific target material parameter of the operating material 5 . In the above variant, in which the receiver 2 receives the refracted radiation 4, the receiver 2 can only when a certain predetermined refractive index as possible receive the radiation 5 4 n of the liquid.

Advantageously, the receiver can 2, the radiation 4 at a given target material parameters received, at a deviation of the actual fuel parameter from the target material parameters the radiation 4 due to varying degrees of optical refraction or deflection of the radiation 4 is deflected past the receiver. 2

If necessary, in particular two level sensors, one for detecting the level of the operating material 5 and another for detecting the material parameter of the operating material 5 , can be provided. In a particularly structurally simple variant, a sensor according to the invention has, for example, a transmitter 1 and at least two receivers 2 , preferably one of the receivers 2 receiving the non-refracted radiation 4 and another receiver 2 receiving the predetermined substance parameters of the dissolved substance receives optically refracted radiation 4 corresponding to liquid 5 . If the actual substance parameter deviates from the target substance parameter of the dissolved substance in the liquid 5 , neither of the two receivers 2 generally receives the radiation 4 . In order to determine the most varied qualities of the substance parameter of the dissolved substance in the liquid 5 , additional, further receivers 2 can optionally be arranged on the container 3 along the spanned refractive plane. List of Reference Numerals 1 Transmitter
2 receivers
3 containers
4 radiation
5 liquid
6 interface
7 powder
8 bulge
9 wall
10 wall
P arrow

Claims (12)

1. level sensor for determining a level of a substance ( 5 , 7 ) in a container ( 3 ) with at least one transmitter ( 1 ) for emitting radiation ( 4 ) and a receiver ( 2 ) for receiving the emitted radiation ( 4 ), wherein the container ( 3 ) comprises at least one wall section ( 9 , 10 ) which is at least partially permeable to the radiation ( 4 ) and the beam path runs from the transmitter ( 1 ) to the receiver ( 2 ) through the interior of the container, characterized in that the wall section has at least one for Beam direction includes oblique-angle interface ( 6 ). 2. Level sensor according to claim 1, characterized in that the oblique-angled interface ( 6 ) forms the entry surface of the radiation ( 4 ) into the container ( 3 ). 3. Level sensor according to one of the preceding claims, characterized in that the beam path runs through a shape ( 8 ) of the container ( 3 ) provided for this purpose. 4. Level sensor according to one of the preceding claims, characterized in that the beam path runs through a corner region of the container ( 3 ) provided for this purpose. 5. Level sensor according to one of the preceding claims, characterized in that at least two sections ( 9 , 10 ) of the formation ( 8 ) are arranged at an angle to one another. 6. Level sensor according to one of the preceding claims, characterized in that the angle of the two sections ( 9 , 10 ) is almost 90 °. 7. Level sensor according to one of the preceding claims, characterized in that the transmitter ( 1 ) or the receiver ( 2 ) are designed to emit or receive infrared radiation ( 4 ). 8. Level sensor according to one of the preceding claims, characterized in that the transmitter ( 1 ) and the receiver ( 2 ) are connected in parallel in the same circuit between only two connections, wherein an electronic component controlled by the receiver ( 2 ) is provided, which Voltage and / or the current between the connections influenced. 9. Level sensor according to one of the preceding claims, characterized in that the receiver ( 2 ) is designed as a measurement-dependent resistance, measurement-dependent capacitance and / or measurement-dependent inductance. 10. level sensor according to one of the preceding claims, characterized in that a control device is provided, the one connected between the connections Has voltmeter. 11. Level sensor according to one of the preceding claims, characterized in that the control unit for one Cycle operation is formed. 12. level sensor according to one of the preceding claims, characterized in that a multiplexer for operation multiple sensors provided with the same control unit is.