GB2086861A

GB2086861A - Controlling operation of filling elements of a filling machine

Info

Publication number: GB2086861A
Application number: GB8126715A
Authority: GB
Original assignee: Seitz-Werke GmbH
Current assignee: Seitz-Werke GmbH
Priority date: 1980-09-26
Filing date: 1981-09-03
Publication date: 1982-05-19
Also published as: JPS5786496A; NL8103789A; KR830007424A; FR2491050A1; DE3036294C2; BR8106149A; IT8149218A0; IT1142731B; SU1069618A3; DD201875A5; BE890363A; DE3036294A1; JPH0260593B2; DK419181A

Abstract

In a method of controlling the operation of filling elements (10) of a bottle filling machine, each of the filling elements includes an electrically actuable valve (19) for controlling the flow of liquid into a bottle placed below the filling element. The commencement of flow of liquid into each bottle after opening of the respective valve (19) is detected by means of a pick-up (46), and the instant for closure of each valve is determined by a computer operation in dependence on a desired quantity of liquid to be filled into the respective bottle. The pick-up (46) may also detect the flow rate. Control may be enhanced by a feedback system comprising a level detector (57) or a weighing machine (not shown). <IMAGE>

Description

SPECIFICATION Controlling operation of filling elements of a filling machine The present invention relates to a method of controlling the operation of filling elements of a filling machine for filling vessels with liquid and to control means for carrying out the method.

In filling machine filling elements including electrically actuable liquid flow control valves it is known to use, as a means for determining the filled levels in vessels filled by the elements, gas lines provided with a bottom intersection point or electrical signal transmitters which come into contact with the liquid, the gas lines or transmitters being introduced into the vessels for the purpose of controlling the filling operation and then being withdrawn at the end of the operation.

A feature of this method of control is that, depending on the desired filled level, the gas line intersections or the signal transmitters must be adjusted in height so that the liquid ascending in the vessel can interrupt the further inflow of liquid either when it reaches the gas line intersection or when it contacts the signal transmitter.

In order to reduce the constructional complication necessary for such height adjustment and also to reduce the number of associated setting operations, a change has been made to the provision of filled level determining means for a number of filling elements outside the vessels.

Thus, in United States patent specification No.

2 949 941 there is disclosed a filling machine with a control common to several filling elements and provided by a control device which, in the filling machine operating cycle, switches the filling elements on over a fairly large, preselected portion of each revolution of the filling machine and switches them off again, each filling element including an electrically actuable valve. During the valve opening period, which is established by electromagnet contact arms slidable along a height adjustable conducting bar arranged at the periphery of a filler of the element, liquid flows into the vessel up to a filled level predetermined by the length of the bar, whereupon after contact with the bar has been interrupted the valves are closed by liquid pressure.In this form of filling element control, which does not include any means insertable into and removable from the vessels to determine the filled levels, difference in such filled levels are not impossible when the operating speed of the machine varies. Thus, inaccuracies due to overfilling may occur in the starting up and running down phases of the machine. Differences in filled level also occur due to differences between individual vessels and filling elements as these differences are not taken into account by the control.

There is accordingly a need for a method of controlling the filling elements of a filling machine, and for control means for carrying out such method, whereby the accuracy of filling is so improved that the variations that previously adversely affected the filled levels are avoided and variable operating speeds of the machine are without influence, so that the vessels can be filled with liquid quantities lying within the desired tolerances and/or those established by, for example, legal requirements.

According to a first aspect of the present invention there is provided a method of controlling the operation of filling elements for a filling machine for filling vessels with liquid, wherein each of the filling elements comprises an electrically actuable flow control valve for controlling flow of liquid into such vessels and means operable externally of the vessels to determine the levels of filling thereof, the method comprising the steps of detecting the commencement of flow of liquid into the respective vessel after opening of the flow control valve of each filling element and determining an instant for closure of each flow control valve by a regulating process in dependence on the desired quantity of liquid to be filled into the vessel.

In a preferred feature of the method, to ensure optimum filling accuracy with the least possible complication of switching equipment while guaranteeing careful treatment of the filled liquid, an individual regulating operation is carried out for each filling element, whereby the quantity of liquid to be filled into each vessel is established as a common value for the regulating operations of all the elements, and for each individual regulating operation an actual value distinct from the common value is processed by computer means. It is possible to process, as the actual value, a value which continuously orients itself to the flow speed of the liquid, or else an average value formed from measured values of the filled levels or of the weight of a number of vessels each filled by one and the same filling element.

According to a second aspect of the present invention there is provided control means for carrying out the method according to the first aspect of the invention, the control means comprising respective detecting means arranged below the flow control value of each filling element in an outlet zone thereof and operable to detect the commencement of flow of liquid into a vessel below the filling element after opening of the valve and to provide an output signal indicative of the detected commencement of flow, setting means for setting a desired liquid filling quantity common to the vessels filled by all of the filling elements and for providing an output signal indicative of the set liquid filling quantity, and computing means for carrying out the regulating process for all of the filling elements, the computing means comprising respective regulating means associated with each filling element, respective input means for receiving the output signal of the detecting means of each filling element, further input means common to all of the regulating means for receiving the output signal of the setting means, and respective output means for supplying control signals to each filling element to effect closing of the flow control valve thereof at an instant determined by the regulating process.

An embodiment of the present invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a schematic vertical sectional elevation of a filling element, in a compression position, of a counterpressure filling machine to which a method and control means embodying the present invention may be applied, and Fig. 2 is a view similar to Fig. 1 and showing, in block diagram form, a control means for controlling the filling element and a plurality of other such filling elements of the machine.

Referring now to the drawings, there is shown in Fig. 1 a filling element 10 of a rotatable counterpressure bottle filling machine of singlechamber construction, the machine itself not being shown in more detail. A plurality of such filling elements 10 are connected to a common annular liquid housing 11 of the machine. The housing 11 is provided at its lower side with an annular pressurising gas chamber 12 and an annular venting chamber 13 with permanently open outlets 14 leading to the atmosphere.

Each filling element 10 comprises a body 1 5 with a valve casing 1 6 and a pressurising gas chamber casing 17. Arranged in the interior of the valve casing 1 6 is a vertically displaceable valve body which is biassed by a spring 18 and which forms, together with a valve seat mounted in the casing 16, a liquid valve 19. An electromagnetic actuating device 21 acts via a vertical plunger 20 on the valve body of the valve 19. When switched into its active state, the actuating device 21 presses the valve body, against the force of the spring 1 8, against the valve seat thereby to provide the closed position of the liquid valve 1 9.

Each valve element 10 further comprises a filler pipe 22 which includes a head 23 pushed from below into the casing 16. The pipe 22 extends through the casing 1 7 so that the upper end of the pipe is disposed opposite to the lower end of the valve 19, a space being maintained therebetween to define a balancing chamber 24. The pipe 22 is fixed in this position by a pin 25 pushed into the casing 1 7 and engaging beneath the shoulder of the head 23. The pipe 22 co-operates with a centering mouthpiece having a rubber seating, the mouthpiece being movable upwardly and downwardly on vertical guide rods (not shown) to surround the pipe 22.

In the region of the pin 25 the casing 1 7 defines an annular pressurising gas chamber 27 surrounding the filler pipe 22.

A pressurising gas valve assembly 28 is laterally mounted on the casing 1 6 and comprises a housing in which a valve disc 29 is mounted on a rotatable support 30. At its free end projecting out of the casing the support 30 is connected to an actuating lever 31, which co-operates with control cams 32 or the like mounted at intervals on the frame of the filling machine at different levels. As the machine rotates, the cams 32 cooperate with the lever 32 of each filling element to pivot the support 32 and thereby the valve disc 29 into the required operating position.A spring 33 presses the valve disc 29 gastightly against a base plate 34, in the surface of which facing towards the valve disc 29 there leads out a pressurising gas feed duct 35 which is connected to the chamber 1 2 and passes through the lower part of the housing 11 and through the casing 1 6. Also leading out into the surface of the baseplate 34 which faces towards the valve disc 29 are a balancing duct 38 communicating with the balancing chamber 24 and a pressurising gas inlet duct 37 communicating with the chamber 27, the duct 37 being connected tangentially to the chamber 27.

The valve disc 28 is provided in its interior with a radial duct 38 having two bores 39 and 40 which are oriented towards the baseplate 34 and dimensioned in correspondence with the mouths of the compression ducts 35, 36 and 37, the bores 39 and 40 being so arranged at a spacing opposite one another that in an operative position they connect together at least two duct mouths via the duct 38.

The casing 16 also includes a vent duct 41 leading to the venting chamber 13, the pressurising gas chamber 27 being connected to the duct 41 via a discharge duct 42 extending from the lower part of the chamber 27 through the casing 17. The discharge duct 42 is in permanent open communication with the venting duct 41 via a nozzle 43.

Laterally mounted in the casing 1 6 and sealed from the exterior is a pick-up 46 which, when influenced by liquid after the valve 1 9 has opened, detects the commencement of flow and the flow speed. For this purpose, a known pick-up for heat tone measurement is suitable, the pick-up being disposed immediately below the outlet of the valve 19 in the space between the valve and the upper end of the pipe 22 and being arranged to extend into the balancing chamber 24.

As shown in Fig. 2, the pick-up 46 and also the electromagnet of the actuating device 21 for the valve 1 9 are connected to an input and output device 47 of a digital computing system 48, which includes, in addition to the device 47 and the elements which constitute a regulator for the filling element 10, a further such input and output device and regulator elements for each further filling element in the-machine, a computing and controlling device 49 common to all filling elements, and a central memory 50, these being in direct reciprocal connection with each other.

Connected to the computing and controlling device 49 is an input device 51 which is common to all the regulators of the filling elements and which serves for setting filled volume values for the bottles to be filled. Also in reciprocal connection with the computing and controlling device 49 is an input and output unit 52, to which is connected a control device 53 of a filled level monitoring device 54, which measures the filled levels of the filled bottles as or after they leave the filling machine. The measured values obtained are utilized for forming correction values for eliminating cause of fluctuation in the regulating operation and are delivered by the input and output unit 52. each separated according to filling element, to the computing system 48 for the purpose of processing.The monitoring device 54 preferably comprises a height-adjustable, horizontal measuring barrier unit 57 consisting of a light or gamma radiation transmitter 55 and corresponding receiver 56, the unit being disposed at the level of the liquid surface of the filled bottles at the outlet from the filling machine or just behind the outlet on a single-track conveying path which effects removal of the bottles at requisite intervals.

Connected to the line between the actuating device 21 and the input and output device 47 are a switching contact 58 and a proximity switch 59 associated with the filling element 1 0. The switch 59 is mounted at a fixed location in that region of the actuating lever 31 and the support 30 in which the valve disc 29 assumes the rotational position required for gas pressurisation of the bottle to be filled and the switch is operated by the lever 31 in this position of the valve disc. Instead of a proximity switch for each filling element, a central control, for example a shift register device, may be provided for all filling elements.

For carrying out a method exemplifying the present invention, with the filling element 10 ready for operation the desired filled volume value for bottles of a particular kind is input by the input device 51 into the computing and controlling device 49 and is stored in the central memory 50.

If an empty bottle to be filled is placed on the lifting device 60 and is pressed by the lifting device against the filling element, accompanied by elevation of the centering mouth 26, centering of the bottle mouth relative to the rubber seating and introduction of the filler pipe 22 into the bottle, then the bottle is in position for gas pressurisation prior to filling with liquid. The valve disc 29 is then pivoted by means of the control cam 32 and the actuating lever 31 out of its rest position and into a pressurising position. In this position, the bore 40 of the duct 38 is connected with the feed duct 35 and the bore 39 of the duct 38 is connected with the inlet duct 37. Pressurising gas flows out of the feed duct 35 into the inlet duct 37 and thence, via the chamber 27, into the interior of the bottle to be filled, as a consequence of which the desired gas pressure is produced.By virtue of the tangential inflow of the gas into the chamber 27, any liquid residues present on the chamber walls and on the filler pipe 22 are simultaneously removed and expelled via the discharge duct 42, the nozzle 43 and the duct 41 into the venting chamber 13. In this gas pressurising condition, with the gas discharge route open to atmosphere, one surface of the actuating lever 31 co-operates with the proximity switch 59 so that the switching contact 58 and therefore the electrical circuit for the electromagnet of the actuating device 21 are closed. As a result, the actuating device 21 is switched to its operative position and the valve body of the closed valve 1 9 is held against its valve seating and secured in the closed position.

As the filling element 10 continues to revolve, after gas pressurisation has been completed and when the actuating lever 31 contacts a further control cam 32, the valve disc 29 is pivoted back into its rest position, causing the supply of gas to be interrupted. The actuating lever 31 is also pivoted out of the effective range of the proximity switch 59, which causes the switching contact 58 to open so that the electrical circuit of the electromagnet of the actuating device 21 is interrupted and the electromagnet de-energised.

The spring 1 8 then moves the valve body of the valve 19, now released by the electromagnet, in an upward direction so that the liquid flows via the balancing chamber 24 and the filler pipe 22 into the bottle. Gas expelled by the entering liquid flows through the discharge duct 42, nozzle 43 and venting duct 41 into the venting chamber 13 and thence via the outlets 14 to atmosphere. As soon as the liquid flows out of the opened valve 1 9, it covers that portion of the pick-up 46 which extends into the balancing chamber 24, which portion, when covered, signals the commencement of flow. The signal indicating commencement of flow is supplied via the input and output device 47 to the computing system 48, which initiates the regulating operation for determining the closure instant for the valve 1 9.

The actual value required for the regulating operation, which refers to the flow speed of the liquid, is also continuously detected from commencement of flow onwards by the pick-up 46 and is delivered, in signal form, for processing via the input and output device 47 to the computing system 48. The computing system 48 calculates the closure instant for the valve 1 9 and, at this instant, supplies via the input and output device 47 a closure signal to the electromagnet of the actuating device 21 for the valve 19, whereupon the electromagnet is energized and the valve 1 9 adopts the closed position. With the output of the closure signal, the regulating operation is terminated.

As the filling element 10 continues to revolve and the actuating lever 31 again contacts a further control cam 32, the valve disc 29 is pivoted into a balancing position, in which the bore 39 of the duct 38 is in communication with the mouth of the inlet duct 37 and the bore 40 with the mouth of the balancing duct 36. The thereby produced flow connection for the gas from the space above the filler pipe 22 to the gas chamber 27 has the consequence that the levels of liquid in the interior of the filler pipe and in the bottle are equalized.

Simultaneously, excess pressure still present in the gas space of the bottle and in the system components connected with this space via the ducts 36 and 37 is relieved via the discharge duct 42, nozzle 43, venting duct 41 and the venting chamber 13. After the pressure relief has been completed, the closure signal is erased by a timing element which is provided in the input and output device 47 and which is switched to an operative state when the closure signal is delivered. The signal erasure causes the electromagnet of the actuating device 21 to be de-energized and the valve 1 9 to be held closed by the pressure of liquid thereabove. As the filling element 10 continues to revolve, the filled bottle is lowered and removed from the filling element.The actuating lever 31 contacts a further control element 32 and is operated to pivot the valve disc 29 back into its rest position. Alternatively, the valve disc 29 can remain in the above-described balancing position until a new bottle has been supplied to the filling element 10 for the next filling operation and has been engaged with the filling element in readiness for the gas pressurisation phase.

At or after the departure of each filled bottle from the filling machine, the content of the bottle is monitored by the measuring barrier unit 57 of the monitoring device 54, which is set at the level of the quantity to be monitored. The monitoring is preferably carried out with a gamma ray, which is directed from the transmitter 55, which contains a gamma ray emitter of very low radiation dose, to the receiver 56. The latter receives fewer rays when, in addition to the bottle wall, the content of the bottle has to be traversed and converts the incident radiation into electrical pulses corresponding to the degree of absorption. These pulses are supplied to the computing system 48 via the input and output unit 52 separately for each bottle filled beneath one and the same filling element.From a number, for example three, individual measurements per filling element average values are formed and are utilized as correction values in the regulating operation of the corresponding filling element 10, as a consequence of which inaccuracies in the filled quantity due to irregularities can be eliminated. If, for example, during the filling there is a change in the temperature and/or the specific gravity of the liquid and if such changes are not taken into account by the relevant average values as correction values, then the average values or correction values should be corrected in accordance with these changes, for example by modifying the setting of the absorption degree.

If the pick-up 46 is adapted to detect the requisite actual value and there is no need for correction of the regulating operation as a consequence of irregularities which do not affect the accuracy of the filled quantity, then the filled level monitoring of the bottles by the device 54 can be omitted and the filling operation can be carried out in the above-described manner but without the monitoring device 54. In this case, however, when a temperature change or a change in the specific gravity of the liquid occurs, the preset common filling value must be corrected by hand or by measured magnitudes.

In a modification, the pick-up 46 is in the form of a light barrier unit and is adapted exclusively for detecting the commencement of flow. The actual value is then formed as a summated actual value in the computing system 48 from a plurality of average values, each of which consists of several, for example, three, values detected by the measuring barrier unit 57 of the monitoring device 54 from bottles filled by one and the same filling element 1 0. In this case, the filling operation proceeds in the above-described manner, but with the difference that, as for each regulating operation measured values for forming the actual values have to be determined by the monitoring device 54, the first regulating operations have to be carried out as a function of the preset value until a first summated actual value is present.The current average value also has to be corrected accordingly when temperature and specific gravity changes in the liquid occur.

Instead of the filled level monitoring device 54, an electronic weighing device for weighing the filled bottles can be used and can be connected to the input and output unit 52 of the computing system 48. The average values from several weighings are utilized and processed as described above for forming a summated actual value or a correction value, and the current average value or correction value, as the case may be, is corrected when a change occurs in the temperature, the specific gravity or the weight of the filled vessel.

In the above-described actuating device 21 for the valve 19, the magnet is de-energized in the rest position of the filling element 10. If so desired, however, the construction of this actuating device could be such that the electromagnet is supplied with current and energized in the rest position.

The actuating device may also comprise, instead of an electromagnet, an electrically controllable, pneumatically operating device.

It will be understood that the afore-described method and control means for achieving accurate filled levels, while dispensing with filled level determining means that must be introduced into and withdrawn from the vessels, is suitable not only for counterpressure filling but also for the other filling systems.

Claims

1. A method of controlling the operation of filling elements for a filling machine for filling vessels with liquid, wherein each of the filling elements comprises an electrically actuable flow control valve for controlling flow of liquid into such vessels and means operable externally of the vessels to determine the levels of filling thereof, the method comprising the steps of detecting the commencement of flow of liquid into the respective vessel after opening of the flow control valve of each filling element and determining an instant for closure of each flow control valve by a regulating process in dependence on the desired quantity of liquid to be filled into the vessel.

2, A method as claimed in claim 1, wherein the step of determining comprises establishing a desired liquid filling quantity common to all of the vessels, determining an actual value indicative of a parameter of the filling operation carried out by each individual filling element, and processing such value in computer means in a respective regulating operation for each filling element to determine such an instant of closure for the control valve thereof as to provide said desired liquid filling quantity in a vessel filled by that filling element.

3. A method as claimed in claim 2, wherein the actual value is related to the speed of flow of liquid during the filling operation.

4. A method as claimed in claim 3, wherein the step of determining further comprises correcting the value of said desired liquid filling quantity in dependence on change in at least one of temperature, weight of the vessel and specific gravity of the liquid.

5. A method as claimed in claim 3, wherein the step of determining further comprises measuring the levels of filling or weights of a plurality of vessels filled by one and the same filling element, forming an average value of the measured levels or weights, and utilising such average value for correction of said actual value in the regulating operation respective to that filling element.

6. A metnod as claimed in claim 2, wherein said actual value is the average value of the levels of filling or weights of a plurality of vessels filled by that filling element.

7. A method as claimed in claim 3, wherein the commencement of liquid flow and the instantaneous value of the speed of liquid flow at each filling element are detected below the flow control valve thereof in an outlet zone of the element.

8. A method as claimed in either claim 5 or claim 6, wherein the levels of filling or weights of said plurality of vessels are measured at the time of or after departure of the vessels from the machine.

9. A method as claimed in either claim 5 or claim 6, wherein the step of determining further comprises correcting the average value in dependence on change in at least one of temperature, weight of the vessel and the specific gravity of the liquid.

10. Control means for carrying out the method as claimed in claim 1, comprising respective detecting means arranged below the flow control value of each filling element in an outlet zone thereof and operable to detect the commencement of flow of liquid into a vessel below the filling element after opening of the valve and to provide an output signal indicative of the detected commencement of flow, setting means for setting a desired liquid filling quantity common to the vessels filled by all of the filling elements and for providing an output signal indicative of the set liquid filling quantity, and computing means for carrying out the regulating process for all of the filling elements, the computing means comprising respective regulating means associated with each filling element, respective input means for receiving the output signal of the detecting means of each filling element, further input means common to all of the regulating means for receiving the output signal of the setting means, and respective output means for supplying control signals to each filling element to effect closing of the flow control valve thereof at an instant determined by the regulating process.

11. Control means as claimed in claim 10, each detecting means being adapted exclusively for detection of the commencement of liquid flow.

12. Control means as claimed in claim 11, each detecting means comprising photoelectric cell means.

13. Control means as claimed in claim 10, each detecting means being adapted to detect the commencement of liquid flow and to measure the speed of such flow.

14. Control means as claimed in claim 13, each detecting means being responsive to temperature.

1 5. Control means as claimed in any one of claims 10 to 14, further comprising measuring means for measuring the levels of filling or weights of vessels filled by the filling elements, and an input and output unit associated with all of the filling elements and connected to the measuring means and computing means to supply to the computing means signals indicative of the measured levels or weights of vessels filled by one and the same filling element.

16. Control means as claimed in claim 15, the measuring means comprising gamma radiation emitting and receiving means for measuring the levels of filling.

1 7. Control means as claimed in claim 15, the measuring means comprising light emitting and receiving means for measuring the levels of filling.

1 8. A method of controlling the operation of filling elements for a filling machine for filling vessels with liquid, the method being substantially as hereinbefore described with reference to the accompanying drawings.

1 9. Control means for carrying out the method as claimed in claim 1, the control means being substantially as hereinbefore described with reference to the accompanying drawings.