EP0658511A1 - System for filling bottles, cans or similar containers with a liquid product - Google Patents

Abstract

In the case of a filling system for filling containers (2) with a liquid product by means of a filling element (1), there is provided on the latter an electric probe (10), which determines the filling level and has a first probe section (11), which forms the lower probe tip and a first electrode (E1), as well as a second probe section (13), which is arranged above the first probe section and forms a second electrode (E2), and a probe section (12), which is designed as an insulator and is situated between the first and second probe sections. A third electrode (E3) is formed on the filling element in the path of the liquid. The electrodes are connected to an evaluation and control electronic unit (15) in such a way that the probe has a first, high-resistance state before the first and second electrodes are covered by the liquid product, has a second, low-resistance state when the first electrode is covered by the liquid product, and has a third, likewise low-resistance state when the second electrode is covered. <IMAGE>

Description

The invention relates to a system according to the preamble of claim 1.

Such a system is known (DE 16 32 004). In the known system, the axially displaceable probe forms with a lower first probe section, i. H. with a lower probe tip a first electrode and with an overlying probe section, namely with the actual probe body a second electrode, which is electrically or galvanically separated from the first electrode by a third probe section designed as an insulator.

When filling a container, the probe extends with the electrode path formed between the first and second electrodes to a level in the container to be filled which corresponds to the response fill level, i.e. the level at which a probe signal causing the closing of the liquid valve is to be generated.

The probe is connected to the control and evaluation electronics via a possibly two-wire measuring line, of which the first wire is connected to the first electrode and the second wire to the second electrode.

The object of the invention is to demonstrate a system in which, while maintaining a simple design of the probe, in particular also with regard to the electrical connections, and while maintaining a simple electrical connection between the probe and the control and evaluation electronics, a probe signal preceding the response level is possible.

To achieve this object, a system is designed according to the characterizing part of patent claim 1.

In the system according to the invention, the probe assumes a low-resistance state at a preliminary filling level before reaching the response filling level, which state differs from the low-resistance state when the response filling level is reached and is determined by the electrical resistance of the liquid filling material on the electrode path which is between the first Electrode and the third electrode are formed.

Characterized in that both electrode paths form an electrode path arrangement in which these electrode paths are connected in parallel and are also parallel to the input of the control and evaluation electronics, and in addition the third electrode is arranged in such a way that it is constantly and already at the beginning of the filling phase in the liquid path of the filling material flowing into the container, the state of the probe corresponding to the provisional filling height is reached when the liquid electrode in the container is occupied by the first electrode or the first probe section forming this electrode. The third electrode, which is preferably formed by a return gas tube surrounding the probe, is located at a clear distance above the second electrode or the response range of this electrode. This return gas tube is then preferably designed such that it also extends into this container when a container is being filled, but with a much shorter length than the probe.

With a control signal, which is derived from the state of the probe corresponding to the provisional filling level, a wide variety of functions can be controlled, for example a filling pause or temporary interruption of the filling process or a reduction in the filling speed, etc.

Developments of the invention are the subject of the dependent claims.

Fig. 1

in vereinfachter Darstellung und im Schnitt ein Füllelement mit einer erfindungsgemäßen Sondeneinrichtung;

Figuren 2 und 3

das Füllelement in einer Darstellung entsprechend der Fig. 1, jedoch bei Erreichen der vorläufigen Füllhöhe bzw. der Ansprechfüllhöhe;

Fig. 4

das elektrische Satzschaltbild der Sondeneinrichtung;

Fig. 5

den zeitlichen Verlauf der Spannung beim Ansprechen der Elektroden.

The invention is explained in more detail below with reference to the figures using an exemplary embodiment. Show it:

Fig. 1

in a simplified representation and in section, a filling element with a probe device according to the invention;

Figures 2 and 3

the filling element in a representation corresponding to Figure 1, but when reaching the preliminary level or the response level.

Fig. 4

the electrical block diagram of the probe device;

Fig. 5

the time course of the voltage when the electrodes respond.

In the figures, a 1 is a filling element which is provided in a large number of further filling elements on a rotating part or rotor of a filling machine for filling bottles 2 with a liquid filling material.

The filling element 1 consists essentially of a housing 3 with the usual liquid channel 4, in which the liquid valve 5 is provided and which on the underside of the housing 3 forms the discharge opening 7 enclosing a return gas pipe 6, via which the liquid filling material is opened when the liquid valve 5 is open flows in the sealing position with the filling element or with a sealing element 8 arranged bottle 2.

The return gas pipe 6 is provided on a valve body 9 of the liquid valve 5, which (valve body) can be moved together with the return gas pipe 6 between a raised open position and a lowered closed position in the direction of the vertical filling element axis FA.

An electrical probe 10, which determines the filling level, is arranged in the return gas tube 6, coaxially with the filling element axis FA, and extends over the lower, open end of the return gas tube 6 protrudes. The return gas duct is formed between the outside surface of this probe and the inside surface of the return gas tube 6.

The rod-shaped probe 10, which in the embodiment shown has a constant circular cylindrical outer cross section over its entire length, has a lower, the lower end or the probe tip forming probe section 11 which has a predetermined axial length in the direction of the axis FA and an exposed surface on its outer surface forms electrically conductive surface or electrode E1. The probe section 11 is adjoined at the top by a probe section 12 which is designed as an insulator and which electrically separates the section 11 from a rod-shaped section 13 which adjoins the upper side of the section 12 and which makes up most of the length of the probe 10, i.e. forms the actual probe body and is in turn formed on its outer surface as an exposed, electrically conductive electrode E2.

The probe section 13 projects beyond the open underside of the return gas tube 6 and also extends through the return gas tube in the interior of the filling element 1 to an upper region of this filling element, on which the electrical connections for the probe 10, which are not shown in FIGS. 1-3, are also provided are.

In the case of the filling element 1, the return gas tube 6 also forms an exposed electrode E3 at least at its lower, open end. In the embodiment shown, the return gas tube 6 is made entirely of an electrically conductive material (metal) for this purpose.

4 shows the block diagram of the circuit arrangement or probe control having the probe. As shown, the return gas tube 6 and the probe section 13 or the electrodes formed by these elements are each connected to the electrical ground of the filling machine, to which (ground) also a connection of a measuring voltage source 14 an evaluation and measuring electronics 15 is connected.

In the embodiment shown, in which the evaluation and measuring electronics 15 are provided separately for each filling element 1, the voltage source 14 supplying a constant measuring voltage is a fixed voltage regulator which is connected with its input to a DC voltage supply, not shown, common to all filling elements 1 and delivers the measuring voltage at its output. The output of the voltage source 14 is electrically connected via an adjustable measuring resistor 16 'and an electrical connecting line 17 to the probe section 11 forming the lower probe tip, the electrical connection 17 within the probe 10 being formed by a conductor 18 which is located inside the probe 10 extends upward from the probe section 11 through the probe sections 12 and 13 and to which a cable forming the electrical connection 17 outside the probe 10 is then connected. Special connections are not required for the probe section 13 and the return gas tube 6 or for the electrodes formed by these components if these components are held on electrically conductive parts of the filling element 1 and these parts are connected to the electrical mass of the filling machine.

The evaluation and measuring electronics 15 furthermore have a measuring circuit 16 which, with its two connections, is parallel to the series connection of the output of the voltage source 14 and the measuring resistor 16 ', i.e. with its one connection via the electrical connection 17 also connected to the probe section 11 or to the electrode E1 there and with its other connection it is connected to the circuit ground.

In principle, it is also possible to provide an AC or pulse voltage instead of a DC voltage for the measuring voltage, here again using a Circuit or controller ensures that the measurement voltage in question is available with a constant amplitude at the output of a measurement voltage source.

FIGS. 1-3 show the closed state to the left of the axis FA and the open state of the liquid valve 5 to the right of this axis.

FIGS. 2 and 3 show the filling of the bottle 2, which is pressed with its bottle mouth 2 ′ against a seal 19 of a centering tulip 20, the seal 19 in turn lying tightly against the sealing element provided on the underside of the housing 3, the bottle 2 is in sealing position with the filling element 1.

As FIGS. 2 and 3 also show, the filling material flowing into the bottle 2 when the liquid valve 5 is open via the discharge opening 7 forms a flow which essentially runs along the inner surface of the bottle 2 or the bottle neck and in FIGS. 2 and 3 with 22 is designated. This flow 22 also necessarily touches the return gas tube 6 or the electrode E3 formed by this return gas tube.

If the mirror S of the liquid filling material 21 is located in the bottle 2 below the probe section 11 or the electrode E1, a voltage is present at the inputs of the measuring circuit 16, which essentially corresponds to the open circuit voltage of the voltage source 14 when the measuring circuit 16 is at high impedance and is designated U1 in FIG. 5.

If, when the bottle 2 is filled further, the mirror S of the filling material 21 reaches the electrode E1 at the time t1, ie the probe section 11 is increasingly immersed in the filling material 21, the measuring resistor 16 'and the resistance which the liquid filling material 21 in the region of Flow 22 or between the electrodes E1 and E3 has a voltage divider with the result that the voltage at the input of the measuring circuit decreases and finally, with sufficient occupancy of the electrode E1 formed by the probe section 11, has a voltage value which is denoted by U2 in FIG. 5. The electrical resistance of the aforementioned voltage divider formed by the filling material is then essentially determined by the distance between the electrodes E1 and E2, and also by the specific conductivity of the liquid filling material and the intensity of the flow 22.

The provisional filling level at which the mirror S reaches the lower probe section 11 and at which the step-shaped drop DU 1-2 of the voltage at the inputs of the measuring circuit 16 occurs from U1 to U2 is denoted by L1 in FIG. 2.

When the mirror S finally reaches the lower region of the sun section 13 or the electrode E2, the resistance formed by the liquid filling material 21 and lying between the probe section 11 and the machine mass is reduced, in particular by the fact that the one which is decisive for this liquid resistance effective distance between the probe section 11 and the probe section 13 or between the electrodes E1 and E2 is only determined by the relatively short length of the probe section 12 and, moreover, the cross section relevant for the electrical fluid resistance is essentially determined by the entire inner cross section, the the bottle 2 has where the lower region of the probe section 13 is located. By reducing the electrical fluid resistance, when the probe section 13 responds at time t2, there is a further step-like drop DU 2-3 of the voltage applied to the inputs of the measuring circuit 16 from the voltage U2 to the voltage value U3.

By appropriate adjustment of the measuring resistor 16 ', the axial length of the probe section 12 can also be achieved, with a corresponding choice, that the two voltage drops DU 1-2 and DU 2-3 are approximately the same size, in each case Case are so pronounced that, depending on these voltage drops, the measuring circuit 16 can deliver special control signals to measuring lines 23.

The fill level at which the probe section 13 responds at time t2 and the voltage applied to the measuring circuit 16 has dropped to U3 is designated by L2 in FIG. 3 and corresponds to a fill level at which the closing of the liquid valve 5 is then initiated.

The following control of the filling element 1 is possible with the probe control, for example. For example, when the voltage has dropped from the value U1 to the value U2 at time t1, a filling pause can be made, i.e. for this purpose, the liquid valve can be closed for a certain period of time, for example, predetermined by a timer or timer, or it can be switched from a higher to a lower filling speed.

Furthermore, it is also possible to initiate these processes (filling pause or switching from a higher filling speed to a lower filling speed) with a time delay, in order to enable additional adaptation to different products, bottles, shapes, etc.

When the probe section 13 responds, i.e. If the voltage U drops further to the value U3 at the time t2, the liquid valve 5 is then closed with the control signal supplied by the measuring circuit 16. Again, this can be delayed in order to correct the fill level.

The measuring voltage is preferably an AC or pulse voltage. This results in the same dependency of the voltage at the input of the measuring circuit 16 shown in FIG. 5, the voltages U1-U3 being the amplitudes of the applied voltage. The measuring circuit 16 has a rectifier circuit which rectifies the voltage present for further processing and evaluation.

The length L2, with which the lower region of the probe section 11 extends into the bottle 2 when it is filled, is optimally chosen for the respective bottle shape and can be optimally adjusted, for example, by exchanging the probe 10 and / or by axially adjusting this probe.

In principle, there is also the possibility of designing the probe 10 in such a way that standardized probe parts and probe parts of different lengths are used for the production of probes of different lengths. For this purpose, for example, the probe section 13 is designed such that it consists of an upper, longer probe section 13 ', to which a probe section 10' can then be attached, for example by screwing, which, in addition to a section 13 'which can be directly attached and which is attributable to the probe section 13 Part 13 ″ also has the probe sections 11 and 12, the optionally usable probe parts 10 ′ then having a different axial length for the part 13 ″ and / or the probe section 11 and / or the probe section 12.

In the embodiment described above, it was assumed that each filling element 1 is assigned its own evaluation and measurement electronics 15. In principle, however, it is also possible for a common evaluation and measuring electronics 15 to be provided for each group which comprises a predetermined number of filling elements 1.

Reference list

1

Filling element

2nd

bottle

2 '

Bottle mouth

3rd

casing

4th

Liquid channel

5

Liquid valve

6

Return gas pipe

7

Delivery opening

8th

Sealing element

9

Valve body

10th

probe

10 '

Probe part

11, 12, 13

Probe section

13 ', 13' '

Subsection

14

Voltage source

15

Evaluation and measuring electronics

16

Measuring circuit

16 '

Measuring resistor

17th

electrical connection

18th

ladder

19th

poetry

20th

Centering tulip

21

Product

22

Product flow

23

Control line

Claims (8)

Filling system for filling a liquid filling material into bottles (2), cans or similar containers, with at least one filling element (1) which has at least one liquid valve (5) which controls the filling material inflow during a filling phase and is arranged in a liquid path as well as at least one probe (10 ) which protrudes at least during the filling phase with a predetermined length over the underside of the filling element (1) and extends into the interior of the container (2), the probe (10) having a lower, the probe tip and a first electrode (E1) first probe section (11) and a second, in the axial direction (FA) of the probe (10) overlying probe section (13), which forms a second electrode (E2) and through a third, designed as an insulator probe section (12) of the first Probe section (11) is separated, and with an evaluation and control electronics (15), which with one, at least two connections Me The β or signal input is parallel to an electrode path formed between the first and second electrodes (E1, E2) and delivers a signal which causes the liquid supply to stop when the electrode path between the first and second electrodes (E1, E2 ) is bridged by the liquid filling material and thus the probe (10) has passed from a high-resistance first state into a low-resistance second state determined by the electrical resistance of the filling material between the first and second electrodes (E1, E2), characterized in that on Filling element (1) at least one third electrode (E3) is provided, which is arranged in the liquid path of the liquid filling material and with the second electrode (E2) on a common connection of the control-evaluation electronics (15), so that parallel to the an electrode path formed by the second electrode (E2) and the first electrode (E1) e from the third electrode (E3) and the first electrode (E1) formed electrode path and when the first electrode (E1) is occupied by the liquid filling material at a preliminary filling level before reaching the response filling height, the probe (10) a third, due to the electrical resistance of the filling material between the third and first electrodes (E3 , E1) assumes a certain low-resistance state, which corresponds to the provisional filling level and is different from the first and second states, and that the control and evaluation electronics (15) have a measuring or evaluation circuit (16) which has the different, the provisional Filling level and the response level corresponding probe resistances detected and delivers a control signal corresponding to the preliminary level as well as a control signal corresponding to the response level. System according to Claim 1, characterized in that the parallel connection of the electrode sections is part of a voltage divider arrangement which is supplied with a measuring voltage and which provides at its output an output signal (U1, U2, U3) which is different in voltage or amplitude for each state of the probe (10) . System according to claim 2, characterized in that the measuring voltage is a DC voltage. System according to claim 1 or 2, characterized in that the measuring voltage is an AC voltage or a pulse voltage. System according to one of claims 2-4, characterized in that the parallel connection of the electrode paths is preferably connected via at least one series impedance (15) to the connections of a voltage source (14) supplying the measuring voltage, and in that the measuring and evaluation circuit (16) with two connections forming a measurement input is parallel to the electrode sections. System according to one of claims 1-5, characterized in that the second and third electrodes (E2, E3) are connected to the electrical ground of the system, which also forms a connection of the control and evaluation electronics (15). System according to one of the preceding claims, characterized in that the voltage divider arrangement comprising the electrode paths is designed in such a way that in the high-resistance first state a first output voltage (U1), after reaching the provisional fill level (L1), a second output voltage (U2 which is smaller than the first) ) and after reaching the response fill level (L2), a third output voltage (U3), which is smaller than the second, is present. System according to one of claims 1 - 7, characterized in that in the case of several filling elements, control and evaluation electronics are provided for each filling element (1) or for a group of filling elements.

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