DE2602229A1 - Indicator of overfilling of tanks - uses oscillator to indicate when level is exceeded when filling vessels and tanks with solid and liquid substances - Google Patents

Abstract

The device comprises a measuring element (8) with means for mounting it securely in the container measuring instrument is affected by the substance when it is filled up to the level of the instrument. There is an oscillator (2) which is connected with this instrument (8), which delivers a signal when the substance fills the container up to the level of the instrument (8). A circuit is connected to the oscillator n2), which responds to its signal and indicates when the substance has reached the instrument level. The substance filling the vessel or tank may be either a liquid or a free flowing solid granular material.

Description

Device for indicating that the level has been exceeded.

The invention relates to a device for indicating that the level has been exceeded when filling vessels, tanks and the like with solid and / or liquid substances.

Well-known level indicators are the water level glass, 'the float and the photocell indicator. The water level glass is a passive indicator that requires human intervention when a certain level is exceeded and has the disadvantage that it can only indicate liquid levels. The swimmer enables an active reaction when a level is exceeded, whereby the mechanical Display above a lever system can be done in many ways. In this case, too the disadvantage still occurs that no solid levels are displayed can. The indicator with photocells does not have the last-mentioned disadvantage on. However, this indicator has the disadvantage that two are at a certain distance elements attached to one another are required, that is to say the light source and the light receiver. This requires additional wiring. Powder has one very unfavorable impact on this scoreboard. Special care and accuracy in the mostly fixed arrangement, the causes are that this indicator is less The object of the invention is to provide an active level excess indicator to be effective on both solids and liquids which requires as little wiring as possible and only a single arrangement, which can be conveniently attached anywhere and against deposited dust not and against adhering material parts is not very sensitive.

The device according to the invention is characterized in that the measuring element with means for attaching this - <measuring element in a container contains, the measuring element through the container up to the level of this measuring element filling substance is influenced and coupled with the measuring element to an oscillator which provides an output signal when the substance rises to the level in the container of the measuring element fills with which oscillator a circuit is connected to which the output signal responds while indicating that the substance has reached the level of the measuring element.

The invention is explained in more detail with reference to the drawings, here 1 shows a block diagram of the device according to the invention; Fig. 2 schematically an embodiment of a capacitive button; Fig. 3 is a block diagram of the logic Switching of the switching and reproducing device; 4 schematically shows an embodiment of two measuring devices connected in parallel; 5, 6 and 7 sections through different ones Execution of the device according to the invention; 8 shows another embodiment of a pushbutton, and FIG. 9 shows an oscillator, detector and amplifier circuit, which is used in the device of the invention. In Fig. 1, 8 denotes a Measuring element, which is formed by a button 1, which is connected to an oscillator 2 whose output is connected to the input of a rectifier and amplifier circuit 3 connected is. The output of circuit 3 is via a galvanically isolating element 4 connected to a logic circuit 5, which is again connected to a switching and playback device 6 is connected. A DC voltage supply source 7 provides the voltage supply of the different items.

The operation of the device is as follows. If in the immediate via the button, which is attached like a probe in the measuring room, the medium itself changes, for example replaced by another medium frd, thus earth locally physical Quantities such as specific mass, heat conduction coefficient, electrical and magnetic Line coefficient changed. A button that Other one these physical quantities can determine, for example 'a temperature-sensitive Resistance, a capacitive element or an inductive element, is in an oscillator circuit housed. The measuring element, the button, is preferably integrated into an active oscillator aufitenommen, which is set in such a way that it is at a certain, minimum Change in the value of the element takes effect. Once effective, the oscillator delivers at its output a certain alternating voltage for a rectifier and amplifier circuit, that when an alternating voltage appears with a predetermined minimum amplitude becomes effective at the input. The rectifying and amplifying circuit is constructed so that the appearance of a sufficiently high AC voltage at the input a higher one Direct current caused by the supply lines of a DC voltage supply source. This change in current is transmitted to a logical one via a galvanically isolating element Circuit transmitted which the information supplied by the change in current converts into control signals that the switching and playback device for excitation control of signaling and / or alarming device. The DC voltage supply source 7 supplies the voltage supply to the measuring element 8 via the primary part of the galvanic separating element. The signal is thus transmitted via the DC voltage supply lines of the measuring organ.

In a preferred embodiment, the measuring element contains a capacitive one Button for observing changes in the dielectric constant (i.e. dielectric losses of the exercise medium). As the capacitance of a capacitor to the dielectric constant of the medium between the plates is proportional, there will be a change in the dielectric constant cause a change in capacitance. When a predetermined capacitance value is exceeded the oscillator 2 becomes effective.

Fig. 2 shows an embodiment of the capacitive button. On one electrically insulating carriers 10 are two concentric, electrically conductive, flat rings, an outer ring 12 and an inner ring, or rather a round one Plate 11 attached. With such an arrangement of the electrodes, a great sensitivity to changes in the dielectric properties of materials achieved in the immediate vicinity of the button.

A plate 13 attached to the other side of the carrier 10 forms one Shearing between the capacitive button and the oscillator.

The measuring element described above is preferably coated with resin, causing bumps or vibrations, pressure or temperature fluctuations and Attack is particularly well resistant in aggressive environments without the self-awareness is impaired. It also results in a good one electrical insulation, which is important when measuring in explosive environments is.

In Fig. 3, 20 denotes a DC voltage / current regulating device, the fuses required for many types of use voltage and current limiting organs, not shown, are provided and furthermore a pair of input terminals for connection to a DC voltage source, a pair of output terminals for supplying the required supply voltage for the measuring element and output terminals +1 and +2 for outputting the different voltages contained in the logical Circuit and the switching and playback device are necessary. An output terminal with positive voltage +3 is with the primary part of the galvanically isolating element or signal transmission organ connected, which in a preferred embodiment consists of a light emitting diode 22, in which case the secondary part is formed by a phototransistor 23. Between the collector and the emitter of the phototransistor 23, a resistor 24 is connected, which is on the emitter side to the positive voltage +1 on the collector side via a resistor 25 to the positive voltage -F2 is connected. The collector of the is via line 26 Phototransistor 23 connected to logic circuit 35. The logic circuit In one embodiment, 35 contains, for example, two measuring elements for display the crossing of two levels are used, three Schmitt triggers 30, 31 and 32, the inputs of which via the controllable IDs 27, 28 and 29, respectively a line 26 are connected in parallel, the variable resistors for setting an appropriate threshold input value of each Schmitt trigger.

The input threshold value of the Schmitt trigger 0 is set in such a way that that this refers to errors in the system itself, since ã means that the operating limits are below certain limits Responds to voltages and / or currents. A with the output of the Schmitt trigger 30 connected pulse amplifier 33 supplies a control signal to the switching and playback device 36 and a blocking signal to the flip-flop Circuit 34. The Schmitt Triggers 31 and 32 are of this type due to the different variable resistors 28 and 29 set that they are on line 26 voltages corresponding to two different Address levels. The Schmitt triggers 31 and 32 are connected to the circuit 34, which contains a number of flip-flops, the control pulses to the switching and playback device 36 deliver.

- The effect of the circuit arrangement already results from the Figure. The higher the current through the primary part of the organ 21, the lower is the voltage through line 26. In the idle state, none of the Schmitt triggers are activated 30, 31 or 32 react, so that no control signal is sent to the switching and playback device 36 is delivered. If, as a result of a fault, a current lower than the quiescent current flows through 22, the Schmitt trigger 30 will respond to indicate an error signal. If a first measuring element detects that a first level has been exceeded, 'will the relevant current flowing through 22 actuate the Schmitt trigger 31 to Generating a first control signal which indicates: "the first level has been reached". If a second measuring element detects that a second level has been exceeded, the associated current flowing through 22 make the Schmitt trigger 32 effective, in order to emit a second control signal which indicates: the second level has been reached ". When an error occurs, the circuit 33 delivers a blocking pulse to the Flip-flop circuit 34 to prevent the display of levels * The switching and reproducing device contains a number of audio-visual reproduction organs such as lamps and horns and organs to excite the same and also organs, the control signals to desired on devices such as pumps, locking devices and the like responding to the level being exceeded can give up.

4 shows an embodiment of two on a support rod 46 attached measuring elements 40 and 41. The llessorban 40 is via a quick-release device 42 is connected to a tube 43 which is fastened to the carrier 46. The center line 44 of the tube 43 closes an angle c <with the center line 45 of the carrier 46 a. The reason for this is that when used in more or less sticky fabrics like crude oil, this substance sticks to the measuring element less quickly provided the measuring element with respect to the liquid level in an inclined, gently sloping position is attached. In the case of a vertically arranged carrier, the angle is in practice <about 450.

In order to prevent the measuring element from flowing down in the event of an immediate impact Filling flow responds, it can be partially surrounding, somewhat widening Cap can be provided that leaves the downward-facing measurement opening free.

If necessary, precautions can be taken to avoid that against the measuring element splashing up filler an undesirable display of a Could result in exceeding the level. For this purpose, the logic circuit should include a timing circuit, which the signal information during a back to a predetermined length of time and at a predetermined instant the stored signal information in the hold circuit with the actually existing one Signal information compares and, in the event of equality, only in the case of exceeding provides a control signal for information indicating a level.

The above-described level excess indicator after the The invention is intended to be adjusted to a specific reference medium, in practice usually air will.

Materials with a dielectric constant sufficient of differs from the dielectric constant of air, which is about 1 when it is in sufficient quantities are available and are sufficiently close to the measuring element, can let this measuring element respond. As materials, for example mentioned are: oil, gasoline, toluene, cement, grain, fodder. Ragged Flaterials have the same effect as long as the rags are not too coarse. Even sticky substances have this effect. If they are too sticky, the measuring device must cleaned for the next use. '4itteIs an easily attachable Support in the form of a tube on which one or more measuring elements are connected in parallel are attached so that only a pair of electrically conductive wires make a connection requires, the device according to the invention is an appropriate, allgel, tein Usable level crossing indicator Figs. 5, 6 and 7 show particular ones Embodiments of measuring organs, which are suitable for use in special environments suitable.

Fig. 5 shows, for example, a -lessorgan in a sheath partially made of metal and partly made of insulating material, in particular for permanent use explosive areas. The metal jacket 50 can be made of stainless steel, for example. Steel made. The surface of the insulating material must not be too large with Be considerate of the generation of static electricity that could create sparks Around the jacket 50, a round plate 51 of insulating material is attached over the a head. 52 is screwed, for example, from stainless steel, which is at the height of the Button 55 has a small, round opening 53. It is at the same height as the button a small, unshielded area made of insulating material, e.g. Teflon, is available, which is large enough to allow the button to respond to the surrounding media, and which is sufficiently small to meet the security requirements when used in permanently explosive areas (unshielded surface should be smaller than about 25 cm2) to Ben'irSen. The measuring element 54 encased with resin is in front the assembly of the protective cover in the tintel 50 clamped.

dough. 6 shows a variant of the embodiment according to FIG. 5. When used of the tiess organ in rooms that are not always explosive but only occasionally the security requirements are less strict (requirement: unshielded Surface smaller than about 50 cm), so that only a smaller part is shielded needs to become. A metal jacket 60 and a head 61 of insulating material form here the shell in which the resin encapsulated measuring element is housed.

Fig. 7 shows yet another variation. This is used in particular to Use in rooms in which extraordinary temperatures can occur, for example in motor housings, in cylinders or in bottles with liquid gases or similar. The button 80, 81 is also from the electronic part of the printed Wiring 71 of the measuring element arranged and can with a surrounding protective head 72 for example made of Teflon, which is resistant to high ambient temperatures, in the measuring room protrude, the measuring element being screwed tightly into the wall by a coupling piece 70 is, while the electronic part is outside the measuring room of the normal operating temperature subject. The capacitor surfaces 80 and 81 of the button have one of these circumstances adapted shape (see also Fig. 8). Neither this training nor the occurring extreme temperatures can affect the display properties of the above Measuring element affect two copper pipes 80 and 81, the center lines of which are mutually connected ceilings that are aligned with one another are isolated from one another in one insulating protective box 72 housed. The tubes form the capacitor electrodes, each by itself Lines with the electronic part of the ltess organs are connected.

The aforementioned embodiments according to FIGS. 5, 6, 7 and 8 in particular when an all Teflon cover is used, are well suited to use in aggressive lines.

It will be evident that for all special environments except the already mentioned, potentially explosive, aggressive, hot or cold environments and an appropriate combination of materials for environments with other special properties fNo the grommet can be found i <ann.

Fig. 9 shows an oscillator, detector and switching amplifier circuit. The oscillator is with the reference number 93, the detector with 92 and the switching amplifier labeled 91. The oscillator 93 includes two transistors T3 and T4. The emitter of the transistor T4 is connected to the potentiometer P, the other terminal of which is grounded and is connected to capacitor C3, the other terminal of which is connected to the connection of resistors R7 and R10, which on the other hand is grounded. The base of the transistor T4 is to the junction of the capacitor and the resistor R5 and the resistor Rll connected to the. on the other hand is connected to earth. The other little ones of resistor R5 and capacitor C1 are connected in common to the junction of the emitter of T3, resistors R7 and R10 and des Capacitor C3 The collector of the transistor T4 is connected to the connection point of the Base of transistor T3 and resistor R2 connected. The other terminal of the Resistor R2 is connected to the cathode of the Zener diode Z and to the collector of the transistor T3 connected.

The capacitor C1 corresponds to the capacitive element shown in FIG. 8 with the plates 80 and 81 and its variant according to FIG. 2 with the plates 11 and 12. Fig.

7 shows a practical form of implementation of the guide element in which the cylindrical electrodes 80 and 81 constitute the electrodes of the capacitor C1. The fig.

5 and 6 show a further, practical embodiment where the capacitor C1 is denoted by the reference number 55. This capacitive element 55 has the Configuration according to FIG. 2. The capacitive elements shown in FIGS should have a relatively strong stray field, the lines of which are perpendicular to the surfaces of electrodes 11 and 12 in Fig. 2 and perpendicular to the cylindrical ones Surfaces of the electrodes 80 and 81 in FIG. 8 extend.

The substance to be detected therefore does not need to be in the space between to penetrate the electrodes of the capacitive element, which is one of the big Represents advantages of the device according to the invention.

The oscillator 93 shown in Fig. 9 operates as follows: normally if the oscillator is in retirement that means if the substance to be detected is far is removed from the measuring element C1. When the 'to be detected substance to the measuring organ C1 closer gomntJ takes the positive feedback from the emitter of transistor T3 to Base of the transistor T4 via the parallel connection of the resistor R5 and the capacitor C1 increases as the dielectric loss increases, causing the oscillator to oscillate begins. The oscillator frequency is between 200 and 400 kHz, preferably between 250 and 350 kHz-. In a practical embodiment of the device according to the Invention, the oscillator frequency was 300 kHz.

The output of the oscillator 93 is connected to the detector circuit 92, which contains the series connection of the capacitor C2 and the resistor R7. the other terminal of capacitor C2 is to the cathode of diode D1 and the junction of resistors R3 and R9 connected. The other terminal of diode Dl, similar to the other terminal of resistor R9 are grounded. The other terminal of the resistor R3 is connected to the junction of resistor R1, resistor R2 and des Collector of transistor T3 connected. The circuit amplifier 9i includes one Amplifier transistor T2 and a switching transistor T1.

The base of the transistor is biased through resistors R3 and R9 and the emitter is grounded. The collector is connected to resistor R4, its other terminal to the junction of the base of the transistor T1 and of resistor R6 is connected. The other clergy of resistance R6 is with connected to a capacitor C4, the other of which is grounded. The emitter of the Transistor T1 is connected to Ibliderrstand R8, the other terminal of which is grounded is. There is also a voltage regulation network; nd that the resistor R1 and contains the zener diode Z, thereby biasing the transistor T2 as well as the biases ftr the oscillator 93 are kept constant.

When the oscillator 93 begins to oscillate, a positive occurs Voltage he the diode D1, which is amplified by the amplifier transistor T2 in this way is that the transistor T1 is conductive, whereby a current of about 12 rA of the DC voltage source is removed. If that means the complete circuit the oscillator, detector 92 and circuit amplifier 91 at rest are, a direct current of about 2 inA is drawn from the little ones 94, 95.

The terminals 94, 95 are connected to the output terminals of the supply circuit 20 in FIG. 3 connected, that is, in the series circuit with the photodiode 22 and several of the circuits of FIG. 9 can be connected to the -, + output terminals of the supply source 20 in FIG. 3 can be connected. The circuit of FIG. 9 also includes a protective diode D2.

The potentiometer P of FIG. 9 can be used to set the level discontinue the substance; at which the transistor oscillator 93 starts to oscillate. The series connection of resistor R6 and capacitor C4 prevents the oscillator frequency to occur over the feed lines. The capacitive element C1 forms one of the the frequency-determining elements of the oscillator.

Claims (16)

PATENTANS PR CHE 1. Device for indicating that the level has been exceeded during filling of vessels, tanks and the like with solid and / or liquid substances, d a d u r c h e k e n nz e i c h n e t that this is a measuring element (8) with means for Attaching this measuring element in a container, the measuring element (8) through the substance filling the container up to the level of this measuring element can be influenced and an oscillator (2) is coupled to the measuring element (8) and has an output signal delivers when the substance fills the container up to the level of the measuring element (8), and that a circuit is connected to the oscillator (2) which responds to the output signal responds and indicates when the substance has reached the level of the measuring organ. 2. Apparatus according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that the measuring element (8). a capacitive button (lo - 13) contains the when the ambient medium changes to the changes in its dielectric constant is responsive. 3. Device according to claim 2, d u r c h g e n nz e i c n e t that the capacitive push button (lo-13) through two concentric, in the same Plates lying flat (11,12) is formed. 4 Device according to claims 2 and 3, d a d u r c h g ek e n n z e i c h n e t that the measuring element (8) contains an oscillator (2) in which the variable Capacity of the button (lo - 13) is housed in such a way that only at the exceeding a predetermined capacity threshold of the oscillator (2) can take effect. 5. Device according to Sp'ruch.4, d u r c h g e k e n n -z e i c Note that the measuring element (8) contains a rectifier and amplifier circuit (3) which is arranged to be responsive to the oscillations of the oscillator (2) a higher current can be drawn from a supply source, with the size of the drawn current can form the signal information. 6. Device according to claims 1-5, d a d u r c h g e k e n nz e i c h n e t that-this is an electrically insulating signal transmission element (4) for contains the transmission of the signal information of the measuring element (8) to a logic circuit, which is galvanically separated from the measuring element. 7. Apparatus according to claim 6, d a d u r c h g e k e n nz e i c h n e t that the signal transmission organ is a light emitting diode (22) un one Has piototransistor (23). 8. Device according to claims 1-7, d a d u r c h g ek e n n z e i c h n e t that this several parallel-connected circuit elements (27, 30; 28, 31; 29, 32) for signaling that various levels have been exceeded. 9. Device according to claims 6-8, d a d u r c h g ek e n n z e i c h n e t that the logic circuit (35) has several Schmitt triggers (30, 31, 32) contains the control pulses to a switching and playback device (36) accordingly deliver the t <transmission signals of the signal transmission organ and each for a different, predetermined one Threshold value half, in order to be able to display at least an equal number of different operating states. 1o. Device according to claims 1-9, d u r c h g ek e n n z e i c h n e t that the measuring element (1o - 1.3) is encased with resin. 11. Device according to claims 1 - 1o, d a d u r c h g ek e n n z e i c h n e t that the measuring element (4o, 41) in relation to a horizontal plane a Has lye sloping downwards. 12. The device according to claims 1-11, d a d u r c h g ek e n n z e i c h n e t that the measuring element has a protective cover (50, 60, 61), with at least on or around the whole button (54) or a part of it, the shell electrically insulating material (61) and the remaining part of the shell made of electrically conductive material (50 resp. 60) exist. 13. Device according to claims 1 - 12, d a d u r c h g e-K e n n z e i c h n e t that the button (60, 81) thermally against the electronic part (71) of the measuring element is insulated by an electrically non-conductive protective layer (72) is surrounded so that he can check for level exceedances by materials in rooms can address, in which a temperature can prevail depending on the operating temperature of the electronic part (71) of the measuring element can be very different. 14. The apparatus of claim 12 or 13, d a d u r c h g ek e n n notices that the insulating material is made of Teflon consists. 15. Device according to claim 13, d a d u r c h g e n nz e i c h n e t that the button consists of two coaxial, aligned, tubes (80, 81) which are electrically insulated from one another and made of electrically conductive material consists. 16. Method for signaling that the i? U'llen has exceeded the level of vessels, tanks and the like with solid or liquid substances, d a d u r c h g e k e n nz e i c h n e t that at least one device according to claims 1 to 15 is arranged in a measuring room, with a two- or three-core feed cable each device via a galvanically isolating device to a DC voltage supply source and a logic circuit is connected. L e r s e i t e