GB2232210A - Food transfer apparatus; valves - Google Patents

Abstract

Flowable food product is removed from a holding tank 1 under pressure and dispensed into trays by a depositor 4. A valve (13-19) (Fig 2) controlling the dispensing process is operated in response to a flowmeter (5) (Fig 2). One form of valve (Figs 3, 4) comprises a silicone rubber tube (15) which can be squeezed by a pneumatically actuated piston (19). Another valve (Fig 7) uses an inflatable tube (72) to squeeze a rubber tube (74) through which the food product flows. A further valve (Fig 8) embodiment uses an inflatable tube (82) to close a rigid nozzle (71). The tank 1 may be cooled by lowering into it a stirrer having hollow vanes (94) (Fig 9) through which ethylene glycol is circulated. The vanes carry scraper blades (97) which contact the sides of the tank. <IMAGE>

Description

FOOD TRZ8iSt',EP!,~METH9D, AN,D~A,P,,PAR3,T,US In convantional food processing, flowable food products are pumped through a pipeline from one vessel to another.

A disadvantage of this transfer arrangement is that the pump tends to break the food product down and reduce its quality. The food product may be mitered into trays travelling along a filling line using a metering device in the form of a piston and cylinder unit. The cylinder has to be refilled at intervals, and this apparatus may have a damaying effect cn food products.

In our patent application No. GB 2 194 820A, we have proposed the use of a holding tank into which the food product is drawn under the effect of vacuum, and from which it is expelled under air pressure. We have also proposed the use of a metering device in the form of a plastics tube which is repeatedly nipped and released between parallel straight jaws.

It is essential that the quantities of food product dispensed into the trays be precisely controlled. It has been found that the accuracy with which food products are dispensed with the apparatus disclosed in the abovementioned specification may be improved as described hereinafter by expelling flowable food product through a system of tubes arranged in the form of an inverted U, one limb of which extends downwards into the holding tank, and the other of which is associated with a flowmeter and provided with an outlet valve. It is also vital that the design of any equipment intended for use in the food processing industry should be such as to permit easy dismantling and cleaning, and this objective is also achieved as described herein. Furthermore, the usefulness of the apparatus may be increased by the incorporation of a number of other features.

In the drawings: Figure 1 is a perspective view of a food holding tank and associated depositor, Figure 2 is a vertical section through the depositor, Figure 3 shows a detail of Figure 2 to a larger scale, Figure 4 is a section on line 4-4 in figure 3, Figure 5 is a graph to illustrate the degree of control of the deposition using the apparatus in accordance with the invention compared with the apparatus of the above mentioned specification, Figure 6 is an elevation of a tank and a separate lid, Figure 7 is a perspective view of the valve arrangement of a modified depositor, Figure 7A is a vertical-section through the depositor of Figure 7 in the open condition, Figure 7B is a similar vertical-section but in the closed condition, Figure 8 is a vertical-section through a further modified depositor in the closed condition, Figure 9 is a section through a food holding tank at a cooling station, Figure 10 is a cross-section on line X-X in Figure 9, Figure 11 is a side elevation of a cooling station.

Figure 12 is a side elevation of tank in a cooling booth, Figure 13 illustrates schematically a bank of cooling booths and associated circuits.

Figure 14 is a graph to illustrate the cooling effect of a booth shown in Figures 12 and 13.

Referring to Figure 1 of the drawings, a cooked food product is drawn under vacuum into a holding tank 1 in the manner described in the above-mentioned specification. With the holding tank positioned adjacent a conveyor 2 for food trays, food product is discharged in measured quantities into the trays by means of a depositor 4 connected to the tank by a pipeline 3. The food product is expelled through the pipeline 3 under the pressure of sterile air applied to a port of the tank.

The pipeline 3 enters the tank 1 through a port at the centre of the lid la and is connected to a tube 1b which extends vertically through the tank and opens near its bottom. The tank 1 is supported by a framework lc on a wheeled base Id. The framework is formed by hollow tubing in order to minimise the number of locations at which dirt may accumulate and to facilitate cleaning.

The pipeline 3 is connected to a depositor head 4a. As shown in Figures 2 and 3, the depositor head incorporates a flowmeter 5 of a commercially available type which generates an electrical pulse for each unit quantity of food product passing through the depositor head. A counter forming part of an electronic control circuit 6 counts the pulses and, on reaching a preset total, closes a valve 7 for a predetermined period of time to allow the full tray under the depositor head to be replaced by an empty tray. The depositor includes a casing 9 having an overhanging arm 8 in which the depositor head is supported. The casing 9 is mounted on vertical posts 10 provided with wheeled feet. A screw mechanism operated by a handle 9a allows the casing to be moved up or down the posts into the most suitable position relative to the conveyor.

The depositor head includes a vertical tube 11 having at its upper end an inlet 12 for connection to the pipeline 3. The tube 11 passes through the floeter 5 which is located within the arm 8 and is secured at its lower end to a fitting 12 onto which a conical valve support ring 13 is fitted. The ring 13 has a circular vertical bore 14 fitted with a silicon rubber tube 15.

The bore 14 is intersected by a radial bore 16 having a screw threaded end portion for receiving an adaptor 17, into which the end of a pneumatic cylinder 18 is screwed.

The piston rod 19 is fitted with a plastics head having a domed forward end. The radius of the domed end is equal to the internal radius of the bore 14 less twice the thickness of the wall of the tube 15. Consequently, when the piston rod is extended, the tube 15 is constricted into the semicircular shape shown in Figure 3A.

Air is supplied to the cylinder 18 through lines 20 from a control unit 21 which is operated by the electrical circuit in response to the counting of the pulses from the flowmeter as described above.

The apparatus described above has a number of advantages compared with that disclosed in the above-mentioned specification.

First, because a finite times elapses between the response of the flowmeter to the passage of a predetermined quantity of product and the full closure of the depositor valve, a small excess quantity of product will be dispensed. The setting of the flowmeter may take this excess quantity into account if it is a constant, but not if it varies from tray to tray. It has been found that the velocity at which product is discharged from the tank disclosed in the above-mentioned specification diminishes as the level of product in the tank falls, so that the metered quantity diminishes with time. This is illustrated in the graph shown in Figure 5 in which curve A shows the results of an experiment using the arrangement disclosed in accordance with the abovementioned specification using a flowmeter positioned where indicated in the figure.The results obtained are plotted with the weight deposited being shown on the yaxis with gradations in grams and the number of deposits being shown on the x-axis. Pn attempt was made to overcome this problem as described in our unpublished earlier patent application No. 8803759 filed on 18 February 1988, by incorporating into the depositor a device arranged to respond to the pressure in the pipeline and adjust the valve opening time accordingly.

This solution was complicated and did not operate satisfactorily. However, the problem has now been solved by the simple expedient of using a system of discharge tubes in the form of an inverted U, one arm of which descends into the holding tank and the other of which is associated with a flowmeter and control valve. The results of an experiment using this invention are depicted by curve B.

Second, the type of valve disclosed in the abovementioned specification employs flat jaws to nip the dispensing tube. Such a valve has a slower response time compared with that of the valve described herein and is much more difficult to dismantle for cleaning. The valve described herein may be dismantled by unscrewing the cylinder from the conical ring and then unscrewing or unclamping the ring itself. Individual parts are reduced to a minimum and moving parts virtually eliminated.

The lid la is hinged to the tank shown in Figure 1.

Figure 6 shows a modified form of tank 1 which is constructed without a lid and may be transported into position at a discharge station beneath a lid 61, at thE centre of which is incorporated a tube ib. The pipeline 3 extending from the tube 1b to the depositor is flexible to enable the lid to be lowered onto the tank. The lid may be supported for vertical movement by mechanism such as that described hereinafter. The use of a lidless tank has the advantage that it may be moved between various stations at which operating equipment carried by detached lids may be lowered into the tank.

Figure 7 illustrates a fan shaped nozzle of a depositor for dispensing a layer of food product intended, for example, to form a covering such as a pie crust on a tray. The nozzle 71 is formed from a plastics tube shaped to form a slot-shaped orifice. An inflatable tube 72 is located adjacent the orifice within a semicylindrical metal support 73. One end of the tube 72 is closed and the other is connected to an air supply pipe.

A back-up plate 74 is provided opposite the tube 72. Air supplied to the tub expands it from the condition shown in Figure 7A to that shown in Figure 7B to constrict the nozzle. Figure 8 is a view similar to Figure 7A showing a modification of this arrangement in which an inflatable tube 82 is housed within a support 83 with an opening into a one side of a metallic fanshaped nozzle, 71. Upon inflation, the tube 82 expands into the nozzle and abuts its opposite wall, so blocking the orifice completely and preventing the food product from dripping from the nozzle when it is closed.

It is sometimes desired to cool the food product before dispensing.

To facilitate cooling of food product within the tank 1 shown in Figure 1, the tank may be moved to a cooling station at which the hinged lid (lf provided) may be swung back, and a cooling unit lowered into the tank as shown in Figure 9. This operation is facilitated by using a separate extraction tube which is inserted through the cover when required. The cooling unit includes a cover 91 in which is journalled the shaft 92 of an agitator 93. The agitator includes hollow vanes 94, and the shaft has concentric inner and outer ducts 95, 96 through which coolant conveniently in the form of ethylene glycol may be supplied to the lower end of the vanes and withdrawn from their upper ends.The vanes are generally elliptical in cross-section and angled relative to the wall of the tank so that, on rotation, the contents of the tank flow over the leading surfaces of the vanes. The tank has a hollow wall through which the coolant may be passed, and lower and upper ports to which coolant supply and outlet hoses (not shown) may be attached when the tank is at the cooling station.

Scrapers 97 on the vanes dislodge product from the inner wall of the tank and force it into circulation within the tank so as to promote cooling of the tank contents by contact with the tank wall. Drive means 98 are provided for rotating the vanes, and ducts 99 serve to conduct coolant to and from the agitator. As shown in Figure 11, the cover 91 may be provided with vertically extending hollow posts 100 through which pass the ducts 99. The posts are guided for vertical movement between wheels 103 mounted on a framework 101 depending from crossbeams 102 of the factory structure. A motor 104 operates gearing for raising and lowering a screw 105 connected to a crosspiece welded to the posts 100. In a modification, the screw is replaced by a fluid-operated ram.

Referring to Figures 12 and 13, a cooling station takes the form of a group of three booths into which the tanks may be wheeled. The tube Ib is not present within the tank in this embodiment. When in position, coolant supply and outlet hoses 110 are connected to the lower and upper ports respectively in the jacket of the tank, the cover 91 opened and the cooling unit lowered under the action of pneumatic cylinders or electrical drive means controlled by an operator using an adjacent switch panel. Valves B and C are opened and ethylene glycol circulated through the cooling unit and jacket (which has helical vanes to guide the coolant - see Figure 9) from the storage tank 111 through lines 112, 113 until the temperature of the food product has fallen to the desired level. The temperature of the surface of the food product is monitored by an infrared thermostat directed at the surface.Means responsive to the thermostat serve to close the valves B and C to terminate the cooling operation and open solenoid valve E and valve A to admit scavenging air to the circuit in the reverse flow direction from line 114 to drive the coolant into the expansion tank through line 115. A non-return valve D prevents the scavenging air entering the circuit through the cooling unit. Following extraction of the cooling unit, the cover is replaced, the hoses disconnected and the tank wheeled to the filling line for insertion of tube Ib and discharge as shown in Figure 1. The construction and operation of the cooling unit is generally as described with reference to Figures 9 to 11.

Figure 14 is a graph showing the rate at which cooling may take place using the proposed apparatus.

It is to be understood that the cooling apparatus described herein with reference to Figures 10 to 13 may be used in plants using other dispensing arrangements.

Claims (14)

1. Apparatus for dispensing a non-liquid flowable food product comprising: a holding tank provided with a cover, an extraction tube extending through the cover and opening into the lower end of the tank, and a pipeline connected to the extraction tube; means for pressurising the holding tank; a depositor comprising an upstanding support, a casing adjustable vertically on the support; a depositor head supported by the casing, the depositor head including a vertically extending depositor tube connected at its upper end to the pipeline and provided at its lower end with an outlet valve, a flowmeter for monitoring flow through the depositor tube, and control means for operating the valve in response to signals generated by the flowmeter.

2. A depositor for flowable food products including a nozzle defining an elongate outlet orifice, a tubular support on one side of the orifice, an inflatable tube within said support, and means for inflating the tube to cause it to expand and close the orifice.

3. A depositor for flowable food product having a nozzle which includes a tube of flexible material through which the product flows, the tube being of circular cross-section and being housed within a rigid sleeve, and a valve member movable radially of the tube, the valve member having a curved head with a radius equal to R-2t, where R is the internal radius of the sleeve and t is the thickness of the tube.

4. A depositor as claimed in claim 3, wherein the valve member is displaceable by piston and cylinder unit, the cylinder of which has a screw connection with the sleeve through which the tube passes.

5. A holding tank for flowable food product to which is attached or attachable a lid provided or providable with an extraction tube; the extraction tube being insertable into the tank when the lid is in a closed position on the tank.

6. A holding tank as claimed in claim 5, in combination with cooling apparatus including a cover for the tank, an agitator extending downwards from the underside of the cover, means on the cover for driving the agitator in rotation; the agitator including a hollow drive shaft and hollow vanes, and means for passing coolant through the shaft and vanes; and a vertically movable support structure for the cooling apparatus.

7. A holding tank and a depositor interconnected by a system of tubes arranged in the form of an inverted U, one limb of which extends downwardly into the holding tank and the other limb of which is associated with a flowmeter and provided with an outlet valve.

8. Apparatus as claimed in claim 1 wherein the cover is separate from the tank and is provided at a dispensing station to which the tank is movable.

9. Apparatus for cooling food product within a movable holding tank, including a cover for the tank, a rotatable cooling unit extending downwards from the cover, means for driving the cooling unit in rotation, and means for supplying coolant to the cooling unit.

10. Apparatus as claimed in claim 9, wherein the cooling unit includes hollow vanes for the passage of coolants.

Apparatus as claimed in claim 9, including heat detecting means associated with the cooling unit for monitoring the temperature of the food product.

12. Apparatus as claimed in claim 9, including means for raising and lowering the cooling unit.

13. Apparatus as claimed in claim 9, including a coolant supply circuit connected to the cooling unit and connectable to a cooling jacket of the tank.

14. Apparatus as claimed in claim 13, including means for admitting scavenging air to the coolant circuit.