This invention relates generally to material filling systems, and more particularly relates to precision filling systems capable of filling containers within tolerance limits of + 0.1% to + 0.5%. The system is applicable for the pre¬ cise dispensing of fluid materials through a wide range of viscosity including creams, but is also usable for the dis¬ pensing of powdered and particulate materials. BACKGROUND ART

Filling accuracies in various packaging fields have been expected only within the range of 2% to 5%, and in such cases it has been necessary to overfill the package or con¬ tainer in order not to be underfilled within the filling tol- erance limits. Particularly in the pharmaceutical field, with some substances costing on the order of $50.00 to $100.00 per ounce, the savings in product cost achievable with equipment capable of accuracies within the 0.1% to 0.5% range is very high and can effect such cost savings as to pay for the equip- ment according to the invention within extremely short times, sometimes within a matter of weeks.

Presently used filling systems use pumping devices such as piston pumps or rotary pumps, both of which have mov¬ ing parts which cause abrasion and the generation of fine par- tides which can and do enter into the product being dispensed, thereby causing particulate contamination. The system accord¬ ing to the invention has no moving parts during the dispensing process and is free of particulate contamination.

Further, in the pharmaceutical field, sterilization is sometimes extremely important, and pharmaceutical companies when running some products operate a third eight hour shift each day solely to dismantle, autoclave the system parts, and reassemble the system. Even with such sterilization techniques there is the continuing possibility of recon amination of the equipment due to handling in reassembly. The system according to the invention is sterilizable without disassembly and in a small fraction of the time required by the present day

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conventional sterilization techniques for such systems.

Finally, the pumping fill systems presently used create two additional problems when dispensing certain types of materials. One problem is foaming which can take place because the materials are not handled in a gentle fashion du to the high peak pressures developed by pumping type dispens ing systems. The second problem is that of molecular shear which causes damage to protein substances, and which occurs in conventional piston type filling equipment as a result of the piston walls being wiped by the piston seals as the sub¬ stance flows through the pump. DISCLOSURE OF INVENTION

The filling systems according to the invention utili pneumatic pressure maintained within closely held tolerance limits to impose a constant dispensing force upon the materi being dispensed, thereby avoiding foaming by providing a low er .average and constant flow rate to the substance being dis pensed. Additionally, since the material being dispensed is not in contact with moving parts during the dispensing opera tion, there is no abrasion and particulate contamination, no is there molecular shearing damage to the products being dis pensed. Also inherent in the system is the ability to steam or gas sterilize the entire system without dismantling any part of it by introducing steam or gas at various points in the system and allowing it to flow through the system out through the dispensing head. The invention in one embodimen utilizes a buffer tank system, and in a second embodiment ut lizes a pressure balancing system.

The buffer tank system minimizes the effect of high gravity head pressure found in conventional deep supply tank Such gravity head pressure reduces as the level in the. tank drops, and can significantly change the amount of product pa ing through the dispensing head if not compensated for. In order to minimize this effect so as to maintain an acceptabl accuracy tolerance, the product to be dispensed is transferr from the supply tank to the buffer tank where the desired pr sure is induced through a pneumatic head which is introduced

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above the product level. The product level in the buffer tank is then allowed to fluctuate within a relatively narrow band of depth so as to negate the effect of changes in grav¬ ity head pressure to a point sufficient for high accuracy filling. It is possible to refill this closed and pressur¬ ized system by forcing the incoming product into the tank under a higher pressure than that of the buffer tank. The air within the tank that is displaced as a result of introduc¬ ing the new product is automatically vented to atmosphere through a precision regulation system which has a high re¬ verse flow capability to any pressure generated in excess of the set buffer tank pressure.

The embodiment of the invention employing the pressure balancing system especially lends itself to high volume fill- ing operations where a single large bulk supply tank can be used to feed directly to the dispensing heads. This system incorporates either a piston or diaphram balancing member sens¬ ing device which controls a three way pneumatic valve for charg¬ ing or venting the dispensing tank. The desired product set point pressure is applied to one side of the balancing member and the actual product pressure is applied to the other side. As the level in the tank drops, the gravity head pressure drops, and this is sensed at the bottom of the tank. Since the balancing member favors the side with the lower pressure, the three-way valve opens and pneumatically charges the tank until the set point pressure and the actual product pressure are equal. If ^" the actual product pressure were to become great¬ er than the set point pressure, the balancing member would act¬ uate the three-way valve to exhaust the excess pressure to at- mosphere. The response time and sensitivity of the system are adjusted by a flow control valve in the charging circuit, and by increasing or decreasing the pressure differential between the charging pressure and the set point pressure.

A primary object of the invention is to provide a pre- cision material filling system capable of dispensing the pro¬ duct with accuracies on the order of one tenth to one half percent.

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Other objects of the invention are to provide novel precision material filling systems as aforesaid which elim¬ inate: particulate contamination of the product being dispen sed, which avoid molecular shear in the product being dispen sed, which eliminate foaming in dispensing products having a tendency to foam, and which are sterilizable without dismant ling and in a relatively short time interval. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a representational view of a system acco ding to the invention showing a. conveyor carrying containers to be filled, a dispensing head, control system and product storage tanks;

Figure 2 is a schematic diagram of a control system for actuating the dispensing system for filling containers un der the dispensing nozzle;

Figure 3 is a schematic and diagrammatic representat illustrating the buffer tank system embodiment of the invent and

Figures 4, 4A and 4B are diagrammatic and schematic representationsof the pressure balancing system embodiment o the invention. BEST MODE FOR CARRYING OUT THE INVENTION

Referring first to Figure 1, there is seen a precis¬ ion material filling apparatus of the buffer tank type desig nated generally as 10. The apparatus consists of a storage tank 11, buffer tank 12, dispensing head 13, control console 14, and a conveyor 15 carrying containers 16 to be filled. In operation, the containers 16 are moved along the conveyor 15 and stop under the dispensing head 13. The movements of the conveyor 15 are synchronized with the actuation of the dispensing head 13 to insure that material flow through the dispensing head only occurs when a container is thereunder. The synchronization system for effecting this timing sequen does not constitute a part of the invention and is generally well known in the art.

As each container is positioned under the dispensing head 13, the conveyor 15 stops, the dispensing head 13 moves

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physically downward in the slot 17 until the dispensing noz¬ zle 18 enters the neck of the container 16. The controls of the console 14 are either manually actuated or automatically actuated for a predetermined time interval t dispense the predetermined required quantity of material into the contain¬ er 16, after which, the dispensing ^" head 13 ^" terminates the flow of material and the head is raised to clear the nozzle 18 from the container 16. The container 16 then moves outward from under the dispensing head, and the next container is moved by the conveyor 15 into position to be filled. The control sys¬ tem for carrying out the sequence, except for the dispensing head movement and conveyor control, is illustrated in Figure 2, to which attention should now be directed.

Electrical power is supplied to the circuitry from any suitable source via the conductor pair 19 through on-off power switch 20. Closure of the power switch 20 energizes the timer 21 which controls the actuation of the dispensing head 13 through a solenoid valve 22 contained within the dispensing head. The controlled output of the timer 21 acts through a normally closed switch 23 which is part of and actuated by a counter 24 under certain circumstances. When the counter is not being utilized, the switch 23 is normally closed, and the dispensing head solenoid 22 is entirely controlled by the ti¬ mer 21. For manual operation, a momentary-make manually oper- able switch 25 is utilized.

Assuming that a container 16 has been properly posi¬ tioned to receive material from the dispensing head 13, de¬ pression and release of the manual switch 25 pulses the timer 21 and starts the timing cycle which will have been preset in accordance with a desired.time interval suitable for deposit¬ ing the desired quantity of material into the container 16. Once the timer 21 has been started by the switch 25, the switch 25 has no further control over the time cycle and the timer energizes the dispensing head solenoid 22 in a suitable fash- ion to open the dispensing head for flow of material there¬ through. The solenoid 22 remains energized for the predeter¬ mined length of time set into the timer 21, and when the timer

times out, it automatically deenergizes the dispensing head solenoid 22 thereby causing the solenoid to shut off the flo of material through the dispensing head 13.

The manual operation is of course utilizable for an selected number of cycles, but must be actuated once for eac desired dispensing cycle. The timing cycle of the timer 21 will normally lie within the range of 1 to 4 seconds, but t timer may have a much higher timing capacity, on the order o 99 seconds.for a suitable digital device. Digital timers of any desired accuracy are of course available, and timing pre cisions of any desired accuracy are available. For most ap¬ plications timing precisions of one tenth of a second will b suitable, but precisions to hundredths of a second may in so cases be necessary or desirable. For automatic sequential multiple continuous filling cycles a.pulse generator 26 is provided, and is actuatable b an energizing control switch 27. The pulse generator is ad¬ justable to produce pulse rates of one to one hundred pulses per minute, and will be set to produce one pulse for each fi ing cycle required. For example, if a complete filling cycl requires six seconds to position a container, fill it and mo the next container into position, then the pulse generator 2 will produce a pulse each six seconds or at a rate of ten pu ses per minute. The timing of the pulse is of course synchr ized with the movement of the conveyor 15 so that the dispen ing head is activated to dispense material at the correct ti in the overall cycle. Each time the generator generates a pulse, the pulse is routed to the start circuit of the timer 21 and actuates the dispensing head solenoid 22 in accordanc with the time interval set into the timer 21-. This cyclic operation will continue indefinitely until terminated either manually by opening switch 27, or automatically under contro of the counter 24.

Each time the dispensing head solenoid 22 is actuate a signal is sent to the count input of the counter 24. If the counter 24 is deenergized, the count signals are ineff¬ ective. However, if the counter 24 is energized by closure

of control switch 29, each count signal from the dispensing - head solenoid 22 registers a count into the counter. When the count signals received by the counter reach a predeter¬ mined total set into the counter 24, the counter automatically opens switch 23 and thereby prevents the timer 21 from further actuating the dispensing head solenoid 22 irrespective of whe¬ ther or not it is receiving start signals from the manual switch 25 or the pulse generator 26. The counter 24 is em¬ ployed in those situations where only a certain number of fill operations are desired and it is desired to have this carried out without human monitoring. If desired, actuation of the switch 23 by the counter can also be utilized to terminate further movement of the conveyor 15.

Understanding now the general operation of the fill- ing system, attention should be directed to the showing of

Figure 3 which illustrates the buffer tank embodiment of the invention. The storage tank 11 is fed from a source of sup¬ ply to a top inlet through a check valve 29 and inlet line 30, and is also supplied from a pressurizing source of cleaned and sterilized air to a head space top inlet through an air regu¬ lator 31, solenoid valve 32 and inlet air line 33. The tank 11 has a bottom outlet transfer line 34 which feeds buffer tank 12 through a solenoid actuated valve 35 and a check valve 36. Storage tank 11 is also fitted with a lower product level sensing switch 37, an upper product level sensing switch 38 and a sight glass 39.

Similarly, buffer tank 12 is fitted with lower and up¬ per level sensing switches 40 and 41 and a sight glass 42. The head space above the product level in the buffer tank 12 is pressurized with cleaned and sterilized air from the air supply through the top iniet line 43, the pressure venting valve 44 and a precision pressure regulator 45. The product outflow from the buffer tank 12 takes place through the bottom outlet line 46 through a manual valve 47 which feeds the dis- pensing head 13 and ultimately the dispensing nozzle 18.

The dispensing head 13 is shown in a closed position so that there is no flow through the dispensing nozzle 18.

Within the dispensing head 13 extending from top to bottom in the flow path is a replaceable section of flexible plas¬ tic tubing 48 which is shown pinched closed between an anvil 49 and the plunger 50 of a piston 51, which latter is urged into the flow closing position by a compression spring 52.

The flexible tubing 48 may be made of silicone rubber to wit stand the elevated temperatures of steam sterilization. The housing of the dispensing head 13 in the region containing t piston plunger 50 is connected through an air line 53 to the th-Eeway solenoid valve 22, the valve being shown in the exha position sothat the piston plunger chamber is vented to atmo phere and allowing the spring 52 to drive the piston to the right to shut off the flow of product through the plastic tu ing 48. The solenoid valve 22 is also connected via air lin 54 to a source of pressurized air so that when the solenoid

22 is energized to rotate the solenoid rotor 55 ninety degre counter-clockwise, the air line 54 is connected to the air line 53 which pressurizes the piston plunger chamber and drives the piston 51 to the left against the pressure of spr 52 and releases the closing pinch on plastic tubing 48 thus permitting flow from the buffer tank 12 through the dispensi head.

Assuming that the system is empty and that it is de¬ sired to start the system up, the conditions are as follows. The product comes from the supply source under a pressur whi is lower than the air pressure at the supply tank inlet air line 33 as determined by the air pressure regulator 31. Add tionally, the pressure in the supply tank 11, at whatever level the product exists in the tank 11 is a higher pressure than the pressure maintained in the buffer tank 12 by air flowing into the buffer tank through the buffer tank top in¬ let line 43 and the precision pressure regulator 45. The level sensing switches 37 and 38 of the supply tank 11 con¬ trol the actuation of solenoid valve 32, and the level sens- ing switches 40 and 41 control the actuation of solenoid valve 35.

When the level of the product in the supply tank 11

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falls to the level of sensing switch 37, switch 37 causes solenoid valve 32 to rotate ninety degrees clockwise and vent the head space of the storage tank 11 to atmosphere and block the supply of pressurized air from the regulator 31. Accord- ingly, with the pressure in the supply tank decreased below the pressure of the product supply source, the supply source feeds product through check valve 29 and supply inlet line 30 into the storage tank 11. At the same time, since there is no product supply in buffer tank 12, the lower level sens- ing switch 40 actuates solenoid valve 35 to open the transfer line 34 so that product flowing into tank 11 may be moved through line 34 and into the buffer tank 12.

The filling procedure continues until two things occur, with the order of occurrence being dictated by the relative level positionings of the storage and buffer tanks with respect to one another. If the product level in the buffer tank 12 reaches upper level sensing switch 41 before the product level in storage tank 11 reaches upper level sens¬ ing switch 38, then the level sensing switch 41 will actuate the solenoid valve 35 and terminate the flow of product into the buffer tank 12 while the storage tank will continue to fill until the upper level sensing switch 38 senses the pro¬ duct level and actuates solenoid valve 32 to rotate the valve rotor ninety degrees counterclockwise and connect the storage tank head space to the source of regulated pressurized air flowing through regulator 31. Since the pressurized air is at a higher pressure than that of the supply source, the stor¬ age tank head space becomes pressurized above the pressure of the supply source and check valve 29 terminates the flow of further product into the storage tank 11.

Even though pressurized air was present in the buffer tank 12 at all times through the precision pressure regulator 45, the higher product pressure from the storage tank caused the pressurized air in the head space to backflow through the buffer tank inlet line 43 and automatically vent through the back pressure vent 56 of the precision regulator 45. When the upper level sensing switch 41 of the buffer tank 12 closed

solenoid valve 35, the back venting terminated. Under the conditions as stated, the system is filled and is static and ready for operation.

In operation, dispensing from the buffer tank 12 tak place through the dispensing head 13 by actuation of the sol noid valve 22 under control of the timer as previously des¬ cribed in connection with the showing of Figure 2. As the l vel in the buffer tank 12 drops, a constant head space press is maintained in the buffer tank 12 by the precision pressur regulator 45. When the product level in the buffer tank 12 drops to the level of the lower level sensing switch 40, the sensing switch 40 opens solenoid valve 35 so that product from the storage tank 11 flows through transfer line 34 unde pressure of product gravity and head space air pressure in t tank 11 and into buffer tank 12. The flow of product into t tank 12 forces head space air in the buffer tank again back through air inlet line 43 and out through the back pressure vent 56 of the precision pressure regulator 45 until the pro duct level reaches upper level sensing switch 41, which upon actuation closes solenoid valve 35 to complete the product transfer from storage tank 11 to buffer tank 12.

The transfer of product from storage tank 11 to buff tank 12 may be carried out even while dispensing through the dispensing head 13 is going on without any change in the pre cision of fill dispensed through the dispensing head 13. Th result is achievable through the fine control of head space pressure in the buffer tank 12 accomplished with the precisi pressure regulator 54, and the fact that the variation in pr duct head within the buffer tank between the level sensing switches 40 and 41 allows for a product head variation only on the order of one foot. In less critical ^' applications, a greater head differential may be tolerable in the buffer tan 12. The variation in product pressure at the bottom outlet due to variation in product head within the buffer tank is i significant because the product head pressure is very small compared to the constantly maintained pneumatic head space pressure, being on the order of one percent (1%). In the

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manner previously described, automatic refilling of the storage tank 11 from the product supply source is effected through the level sensing switches 37 and 38 and solenoid valve 32, and this automatic supply tank refilling operation can proceed whether or not a transfer of product from the storage tank to the buffer tank is in process.

The embodiment of Figure 4 makes possible the elimina¬ tion of the two tank system of Figure 3 and permits the use of a single large dispensing supply tank because variations of product pressure at the dispensing head are eliminated ir¬ respective of the level of product within the tank. This is achieved by a novel system in which the product pressure at the bottom of the tank is maintained constant irrespective of the product level. This is effected through a novel control system which is illustrated in the showing of Figure 4 to which attention should be now directed.

The dispensing head 13 is fed through a valve 57 from a large dispensing tank 58 which latter is provided at its top with a product inlet line 59 and a pressurizing air inlet line 60. The tank 58 is also provided with lower and upper level sensing switches 61 and 62 which control the actuation of solenoid valve 63 so that additional product from the sup¬ ply 64 may, when required, flow through check valve 65 and opened solenoid valve 63 and a sub-micron biological type filter 66 through the product inlet line 59 into the tank 58. The tank 58 may be a large tank on the order of twenty feet in height and holding perhaps two thousand gallons of product. Tanks of this size can develop large head differentials which could result in pressure differences on the order of nine PSI from maximum to minimum fill with aquaeous solutions.-

The pressurizing air for tank 58 supplied through in¬ let line 60 reaches the tank 58 through a sub-micron biologi¬ cal type filter 67, a volumetric flow control 68 and an air feed line 69 which connects to two ports 70 and 71 of a three- way pneumatic valve 72. The valve port 70 is a charging port through which the tank 58 is charged with pressurized air from air line 73 fed by pressure regulator 74 from a constant

pressure filtered and sterilized air supply via air lines 75 and 76. The tank 58 is vented of over-pressure through venting port 71 and vent line 77 of the pneumatic valve 72 when the valve is appropriately positioned to effect that e In the diagrammatic showing of Figure 4A, the pneuma valve 72 is illustrated as having the charging port 70 and i let pressurized air line 73 connected within the valve by shiftable conduit section 78, while in the showing of Figure 4B, the venting port 71 and vent line 77 are shown so inter- connected by the shiftable conduit section 78 during a tank venting operation. Figure 4 illustrates the conduit sectio

78 in a position intermediate the charging and venting ports and representing a condition where the pressurization in the tank 58 is exactly at the desired set point so that neither charging nor venting is desired.

The shiftable conduit section 78 of the pneumatic valve 72 is positionally controlled by means of a control ro

79 which is coupled to a piston 80 disposed within a pressur differential sensing controller device 81. The controller device 81 could be a diaphram type instead of a piston or cy inder type if considered desirable. The piston 80 divides t controller device 81 into two interior chambers 82 and 83, t chamber 82 being a product pressure sensing chamber which is connected to a product pressure sensing device 84 at the bot of the dispensing tank 58 by ά. product pressure transmitter whereas the chamber 83 is a reference pressure chamber which receives pressurized air from the constant pressure air supp through pressure regulator 86. The pressure sensor 84 and pressure transmitter 85 provide a one-to-one transmission of pressure to the controller 81 from the tank 58 while isolati the product from the controller 81.

The reference pressure in chamber 83 is set at the pressure which it is desired to have at the bottom of dispen ing tank 58, so that this pressure is that which is presente to the dispensing head 13. The charging pressure regulator is set at a pressure typically, but not necessarily, five PS higher than the reference pressure in chamber 83, as determi

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