GB2174683A - Adjustment of the volume of scavenging and/or froth removing devices of can filling and closing plants - Google Patents

Abstract

An arrangement is proposed for the capacity-dependent adjustment of the gas volume which is supplied to the nozzles of a gas-supplying device disposed beneath the lid and/or to the outlet means of froth destroying members of can filling and closing plants. An initial pressure is ensured for the gas, such as CO2, which is used for the gas supply and such pressure is independent, even with variable capacities of the machine. Since the required quantity of gas can vary, depending on various factors, a control pressure is produced in a control medium and influences pressure regulators in the feed circuit of the gas-supplying nozzles, so that the gas pressure is set to a pressure which is proportional to the control pressure. In addition, this control pressure is converted into an electrical control signal which is adjustable in accordance with variable desired values and directly controls the capacity of the plant by influencing the r.p.m. of the main drive motor. This electrical control signal, which is proportional to the control pressure, is also used to change the control pressure via the intermediary of prescribed desired values. In this manner, the gas requirement is set according to the conditions and limited to the necessary extent.

Description

SPECIFICATION Arrangement or system for the capacity-dependent adjustment of the volume of scavenging and/or froth removing device of can filling and closing plants The present invention relates to an arrangement for the capacity-dependent adjustment of the volume of gas which is supplied to the nozzles of a gas-supplying device disposed beneath the lid and/or to the outlet means of froth destroying devices of can filling and closing apparatus which include a speed-adjustable drive means for driving the filling apparatus, the can and lid conveyor apparatus and the closing apparatus, a source of gas pressure which is connectable to the nozzles or froth destroying members via the intermediary of at least one valve control circuit, and means for actuating the valve control circuit which respond to the presence or absence of cans and/or lids.

Gas-supplying means for can filling apparatus are known (cf. German Patent No. 1 931 905 or German Auslegeschrift No. 1 511 670). It is also known with containers other than cans to remove the air from the top space of the filled containers by introducing a neutral or inert gas (cf. German Auslegeschrift No. 1 177 065). It is particularly necessary to supply such gas when caps are to be filled with beverages since the air present in the top space would otherwise alter the taste of the contents and, when associated with very acidic beverages, the air would induce the formation of corrosion on the inner surface of the can lid. Gas must be supplied immediately prior to the lid being attached and seamed-on. Carbon dioxide is frequently used as the protective gas.For this purpose, the gas is directly introduced into the top space of the filled can by means of an appropriate gas-supplying nozzle, such process being effected immediately prior to the lid, which has likewise been brought into position, being placed upon the can and being sealingly joined to said can by means of a double seam.

An extremely pure gas which is relatively expensive has to be used for the gas supply, so it is desirable for the gas to be introduced in an appropriate and economical manner. On the other hand, it is necessary to supply a sufficient quantity of gas so that all of the residues of air can be reliably removed from the top space of the can. However, various influencing parameters are known which affect the process. Thus, the normal volume of the emergent gas alters with the gas pressure which prevails in the feed line to the gas-supply nozzle. when the gas supply capacity is set to the normal machine capacity, the quantity of gas supplied in no longer the desired quantity if the machine capacity changes. The requirement also depends upon the type of contents, the filling speed and the filling temperature of the contents.

In filling plants for beverages containing carbon dioxide, problems arise due to the formation of froth when the cans are being filled with the beverages. It is known, therefore, to provide such filling plants with so-called froth destroying means or devices to destroy the bubbles on the surface. These froth destroying devices are comb-shaped nozzles from which carbon dioxide, for example, is blown into the cans so that bubbles which contain air and are mostly relatively large in size can be destroyed by the gas jet. Here also the action is dependent on the pressure and, in turn, the pressure is dependent on the capacity of the filling plant.

Modern filling and closing plants are designed for production capacities of 2,000 cans per minute or more. In such plants, operating conditions may occur which require a reduced operating speed. Thus, for example, the temperature of the contents during the filling operation can influence the maximum operating speed, as can the carbon dioxide content. It is also possible that empty cans can only be stopped and released again at a reduced machine capacity. It is known, therefore, to provide such filling and closing plants or apparatus with drives for driving the moving component parts of the supply means for lids and cans and of the filling apparatus and the closing apparatus, the speed of such apparatus being steplessly adjustable. If it is necessary to reduce the machine capacity, the volume of gas used to supply gas to the top spaces of the cans may be extremely large.In addition, the excessive gas flow has a disturbing influence on the surface of the contents and causes the contents to be spilled. However, since accurate minimum filling quantities have to be maintained, it is necessary for a greater filling quantity than is actually required to be introduced as a precautionary measure. In turn, the gas requirement may be too little with increased capacities, thereby possibly causing the taste of the contents to be affected or causing corrosion.

It is an object of the invention to overcome the above-described disadvantages. Such an arrangement should permit large variations in the capacity of the plant during high, normal through-put capacity whilst ensuring, nevertheless, that no more than the required filling quantity needs to be introduced into the can and yet ensuring a reliable supply of gas to the top space with an economic means for introducing the gas consumed.

Thus, according to the present invention there is provided an arrangement for the capacitydependent adjustment of the volume of gas which is supplied to the nozzles of a gas-supplying device disposed beneath the lid and/or to the outlet means of froth destroying devices of can filling and closing apparatus which include a speed-adjustable drive means for driving the filling apparatus, the can and lid conveyor apparatus and the closing apparatus, a source of gas pressure which is connectable to the nozzles or froth destroying members via the intermediary of at least one valve control circuit, and means for actuating the valve control circuit which respond to the presence of absence of cans amd/or lids; wherein a control pressure generating circuit is provided for generating a control pressure in a pressure medium, more especially air; solenoid vlaves are provided which are operable to respond to the absence or presence of cans and/or lids, with the or each valve control circuit including pressure regulators which are provided upstream of said solenoid valves and are actuable by the control pressure, said pressure regulators controlling the feed pressure for the nozzles or the froth destroying devices in dependence upon the control pressure; an electrical control circuit is provided which includes a transducer for converting the control pressure into an electrical signal which is proportional to said control pressure and for generating an electrical control signal which is supplied, as a control parameter, to the adjustment device of a steplessly adjustable drive motor and to a limitvalue switch which generates an actuating signal for actuating the setting devices of the control pressure generating circuit for lowering or raising the control pressure.

This arrangement fully excludes the possibility of influences arising due to pressure variations in the gas supply line. The supply of gas is controlled by the variable control pressure in a control fluid, the control pressure in this fluid being adjustable so as to be dependent on the machine capacity in a predetermined manner. The arrangement always operates with sufficient gas volume without the gas consumption exceeding the required amount, even when the machine capacity varies considerably. Gas is introduced, therefore, in an extremely sparing and economical manner. Since, even with a reduced machine capacity, the gas requirement is adapted exactly to the modified machine capacity, there is also no risk of portions of the contents spilling from the can due to the gas flows being to strong.As a consequence of this, the filler only needs to introduce the prescribed filling quantity in an accurately metered manner and does not need to provide excess safety quantities. The reduced consumption of gas and the reduction in the required contents-quantity actually introduced result in a considerable saving of costs. However, the apparatus ensures in a very reliable manner that the quality of the beverage is maintained, even when there are considerable changes in the throughput capacity of the machine. There is also no danger of corrosion phenomena-caused by air remaining in the top space-adversely affecting the storage ability of the container.

The sub-claims relate to advantageous further developments of the features described in claim 1.

The invention will be described further, by way of example, with reference to the accompanying drawings showing the circuit structure of one embodiment and in which: Figure 1 is a schematic illustration of a control pressure generating circuit and a valve control circuit forming with the circuits of Fig. 2, a control system; and Figure 2 is a schematic illustration of a valve control circuit and an electrical control circuit.

The two figures together schematically illustrate the circuit structure of the inventive arrangement or control system for the capacity-dependent adjustment of the volume of gas which is supplied to the nozzles of a gas-supplying device disposed beneath the lid and/or to the outlet means of froth destroying devices of can filling and closing plants.

The arrangement substantially includes four main sections which are denoted by A, B, C and D and are defined relative to each other by dash-dotted lines. The control pressure generating circuit is denoted by A and is connected to a source of pneumatic or air pressure via the intermediary of a line 50 and via the intermediary of a shut-off valve 1, a fine-mesh filter 2 and a water separator 3. A pressure monitor 4 ensures that the plant is switched-off if there is no initial pressure. The pressure is reduced, via the intermediary of a pressure reducing valve 5, from the input pressure of, for example, 6 bars, to the maximum permitted control pressure of, for example, 100 mbars. When the desired control pressure is exceeded, an excess-pressure valve 6 opens to protect the switching plant from being damaged.The pressure thus set in the feed line 51 is stored in the reservoir 7 with sufficient capacitance and indicated by the pressure indicator 8. On the basis of this controlled initial pressure, a control pressure is produced in the discharge line 14 of the control pressure generating circuit. At one end, the line 14 is connected for this purpose to the initial pressure line 51 via the intermediary of a flow throttling means, such as needle valve 10, and via the intermediary of a two-position solenoid valve 9 which is normally closed. At the other end, the discharge line 14 communicates with the ambient atmosphere via the intermediary of a further two-position solenoid valve 11, a flow throttling means such as needle valve 12, and a dirt filter 13. The rate of increase and descent of the pressure in the discharge line 14 is defined by the needle valves 10 and 12. The two valves 9 and 11, which are normally closed, ensure that the pressure existing in the discharge line 14 is maintained. If it is desirable to change the pressure, the valve 11 is opened to reduce the pressure, or respectively the valve 9 is opened to raise the pressure, until the particular desired control pressure is attained.

Two valve control circuits B and C are fed by the discharge line 14. The valve control circuit B is associated with the gas-supplying nozzle for supplying gas beneath the lids of the cans, while the valve control circuit C is associated with the froth destroying members 35.

Both valve control circuits B and C are supplied from a source of gas pressure-by, for example; a CO2 pressure tank,-via the intermediary of the line 52, that is to say via the intermediary of a shut-off valve 16, a filter 17 and a safety valve 18. A pressure monitor 19 switches-off the plant when there is insufficient pressure in the line 53.

A primary or first line 54 branchns-off from the gas supply line 53 via the intermediary of a pressure reducer 20, having a pressure indicator 21, and a flow meter 22. The pressure prevailing between the pressure reducer 20 and the flow meter 22 is indicated in the indicator 21. It is important that this pressure be always kept constant, irrespective of other changes in the plant, so that the flow meter 22 always indicates the actual volume of flow. A pressure regulator 23 is disposed between the flow meter 22 and a two-position solenoid valve 24. This pressure regulator 23 is controlled by the control pressure in the line 14, so that a pressure which is proportional to the control pressure in 14 is indicated at the outlet of the pressure 23.

Such a pressure is the supply pressure at which the CO2 is supplied to the nozzle 26 of the gassupplying device disposed beneath the lid. The supply is additionally controlled by the twoposition solenoid valve 24 which closes the line when suitable sensors indicate the absence of a can or lid. The gas-supply pressure and the changes therein may be observed via the intermediary of the pressure guage 25. Since the opening and closing of solenoid valves, such as the valves 24 and 28 in the valve control circuit B, may influence the control pressure in the control line 14, such temporary interruptions are absorbed in the pressure compensator 15 (reservoir which is associated with the line 14.

In the example as illustrated, a further gas outlet 26a is associated with the gas-supplying nozzle. This arrangement causes CO2 to be conducted into an area directly above the gassupplying nozzle 26, so that the air is replaced by CO2 gas in this area. This allows for the fact, by supplying gas via the intermediary of the nozzle, an air flow is produced which tends to enter the top space of the can behind the gas stream. The additional gas-supplying nozzle ensures that only CO2 gas is included as this flow for the relevant period of time. This additional discharge nozzle 26a is fed via the intermediary of the line 55 which is connected to the gas supply line 53 via the intermediary of a pressure reducer 27, a suitable two-position solenoid 28 which is switchable in synchronism with the solenoid 24, and a guage 29.

The supply line 53 also supplies the froth-destroying members 35 of the valve control circuit C, a plurality of such froth destroying members 35 being provided in most cases. The froth destroying members are connected to the supply line 53 via the intermediary of a pressure reducer 30. The set pressure is kept constant and is indicated by the gauge 31. A pressure regulator 32 is provided downstream of the guage 31 and, just like the pressure regulator 23, it is controlled by the control pressure in the line 14. The pressure which is thus regulated is indicated by the guage 33 and supplied to the froth destroying members 35 via the intermediary of two-position solenoid valve 34. The valves 34 are actuated in synchronism like the valves 24 and 28.

The actual control pressure in the line 14 is indicated by guage 36 and supplied to a pressure absorber 37 which produces an electric current signal, proportional thereto, in the electrical line 63. The current signal may vary between 0 mA and 20 mA, for example, in dependence upon the control pressure in 14. The current signal is converted in a converter 38 into a proportional voltage signal which is supplied to an analog computer 40 of the electrical control circuit D via the intermediary of the line 64. A desired-value signal may be supplied to the analog computer 40 as a further input variable by the adjustable potentiometer 39, for example, and such a potentiometer is set according to the desired or required quantity of CO2 gas. The maximum direct voltage produced in the converter 38 is, for example, 10 V.This voltage is modulated in the analog computer 40 in accordance with the following equation:

In this equation: a= flow constant V= flow quantity F= outlet cross-section = coefficient for nozzle form (0.95) Ap= pressure before the outlet aperture y= specific weight The analog computer 40 produces an output signal which is proportional to the actual flow quantity of the quantity of CO2 (flow meter 22).

Since the quantity of gas per can, as required to rinse or scavenge the top space of the can, only changes very slightly within a range of normal operating speed, it may be assumed that, within this range, the traversing quantity of gas behaves approximately proportional to the working speed of the plant or respectively to the speed of its drive motor 42.

In the preferred embodiment as illustrated, therefore, the output signal of the analog computer 40 is supplied directly to adjustment device 41 as a control parameter or variable via the intermediary of the line 65, said adjustment device 41 controlling the r.p.m. of the steplessly adjustable drive motor 42 via the intermediary of the line 66. The actual r.p.m. is supplied to the adjustment device 41 by a direct voltage in the line 67 and is produced in the direct -current generator 43-which is securely connected to the drive shaft of the motor 42-and is indicated at 46.

However, the output signal of the analog computer 40 is additionally supplied as a control variable to an electronic limit-value switch 44. The electrical output lines 60 and 61 of said switch 44 are connected to the two solenoid valves 9 and 11 of the control pressure generating circuit A. The prescribed limit values, according to which the switch 44 operates, may be introduced via the intermediary of one or a plurality of voltage dividers 45 having output voltages which are preselected according to operating conditions. If the specified limit-value is greater than the input signal of the limit-value switch 44, the solenoid valve 9 is actuated to ensure a corresponding increase in pressure in the control line 14. Once the desired pressure is attained, the valve 9 is released and closes, so that the set pressure in the line 14 is maintained. If a pressure reduction is required, a corresponding control signal is produced via the intermediary of the line 61 for the solenoid valve 11 which permits flow of air from the control pressure line 14 to the atmosphere until the desired pressure in the control pressure line 14 is attained. The indication at 46 is an indication of the r.p.m. of the motor 42 and hence of the throughput capacity of the plant.

Claims (7)

1. An arrangement for the capacity-dependent adjustment of the volume of gas which is supplied to the nozzles of a gas-supplying device disposed beneath the lid and/or to the outlet means of froth destroying devices of can filling and closing apparatus which include a speedadjustable drive means for driving the filling apparatus, the can and lid conveyor apparatus and the closing apparatus, a source of gas pressure which is connectable to the nozzles or froth destroying members via the intermediary of at least one valve control circuit, and means for actuating the valve control circuit which respond to the presence or absence of cans and/or lids; wherein a control pressure generating circuit is provided for generating a control pressure in a pressure medium, solenoid valves are provided which are operable to respond to the absence or presence of cans and/or lids, with the or each valve control circuit including pressure regulators which are provided upstream of said solenoid valves and are actuable by the control pressure, said pressure regulators controlling the feed pressure for the nozzles or the froth destroying devices in dependence upon the control pressure; an electrical control circuit is provided which includes a transducer for converting the control pressure into an electrical signal which is proportional to said control pressure and for generating an electrical control signal which is supplied, as a control parameter, to the adjustment device of a steplessly adjustable drive motor and to a limit-value switch which operates an actuating signal for actuating the setting devices of the control pressure generating circuit for lowering or raising the control pressure.

2. An arrangement as claimed in claim 1, wherein the control pressure generating circuit includes an apparatus for producing a predetermined, constant admission pressure, and the control pressure line is connected to said apparatus via the intermediary of a flow throttle means and a solenoid valve and communicates with the ambient atmosphere via the intermediary of a solenoid and a flow throttle and wherein the two solenoid valves which are normally closed, can be changed-over into their open position by means of the electrical control parameter until the desired control pressure is attained.

3. An arrangement as claimed in claim 1 or 2, wherein each valve control circuit is connected to the source of gas pressure via the intermediary of pressure-reducing and regulating means, each of the sources of gas pressure supplying to the respective pressure regulator an initial gas pressure which is independent of the setting of the drive motor and, hence, independent of the throughput capacity of the can filling and closing plant.

4. An arrangement as claimed in claim 3, wherein a gas flow meter is disposed between the pressure-reducing and regulating means and the pressure regulator for the gas-supplying nozzles.

5. An arrangement as claimed in claim 4, wherein the electrical control circuit includes an analog computer or an equivalent apparatus which modulates the voltage signal proportional to the control pressure and an electrical control signal which is proportional to the flow quantity of the gas and can be directly supplied to the adjustment device or limit-value switch respectively.

6. An arrangement as claimed in claim 5, wherein the analog computer and the limit-value switch have respective setting means associated therewith.

7. An arrangement for the capacity-dependent adjustment of the gas volume which is sup plied to the gas supplying device substantially as herein described with reference to the accompanying drawings.