GB2168943A

GB2168943A - Vacuum treatment apparatus

Info

Publication number: GB2168943A
Application number: GB08531716A
Authority: GB
Inventors: David Reznik
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-12-26
Filing date: 1985-12-24
Publication date: 1986-07-02
Also published as: GB2168943B; GB8531716D0; IL77171A0; AU5163385A; JPS61211222A; IT8548985A0; ZA859146B; FR2575146A1; DE3544849A1; AU574877B2; IT1181999B; FR2575146B1; CA1262150A

Abstract

A vacuum treatment chamber 10 has its interior maintained at predetermined vacuum and temperature conditions, and includes an inlet port 12 and an outlet port 14. Rotary feeders 18, 20 within the enclosure are maintained at the vacuum and temperature conditions of the interior thereof and communicate respectively with the inlet port 12 via a conduit 22 and with the outlet port 14 via a conduit 24. The conduits are filled with a condensible gas by way of conduits 26, substantially to the exclusion of atmospheric air, and sealing apparatus is coupled to each conduit 22, 24 and is arranged for sliding engagement with a relatively small portion of the periphery of the respective rotary feeder. This provides communication between each conduit and the respective rotary feeder while reducing the amount of condensible gas permitted to enter the vacuum enclosure. Articles to be treated, such as cans, are supplied to the inlet port 12 by a conveyor 28 and pass through the sealing apparatus to the feeder 18. From there they pass across the chamber on a conveyor 32 and, after treatment, leave the chamber again via the feeder 20 and the outlet 14, falling by gravity down the conduit 24. <IMAGE>

Description

SPECIFICATION Vacuum treatment apparatus This invention relates to vacuum treatment chambers and is particularly concerned with materials handling in such chambers, with particular reference to rotary feeders which can be used for this purpose.

Various types of rotary feeders are known for differing applications. When used in vacuum applications, for permitting ingress and egress of goods from a vacuum chamber, conventional rotary feeders comprise a circumferential seal which is designed to minimise the leakage of air into the vacuum. Such seals are extremely cumbersome and expensive and involve significant frictional drag on the moving parts, and therefore require frequent and extensive maintenance.

The use of a rotary feeder of the above general type in the context of a vacuum system having a sealing sleeve filled with a condensible gas is described in Israel patent 50398.

The present invention seeks to provide an improved vacuum system incorporating a rotary feeder and more particularly a vacuum treatment system incorporating a rotary feeder which is suitable, inter alia for vacuum applications of the type described in the aforesaid Israel patent 50398.

In accordance with the present invention, a vacuum treatment chamber comprises an enclosure having means for maintaining the interior at predetermined vacuum and temperature conditions, and having at least one access port, a rotary feeder disposed within the enclosure and being maintained at the vacuum and temperature conditions of the interior thereof and communicating with the access port and sealing means coupled to the access port and arranged for sliding engagement with a relatively small portion of the periphery of the rotary feeder, for providing communication between the port and the rotary feeder. The remainder of the rotary feeder is preferably open to the interior of the vacuum enclosure.

If a condensible gas is passed through the access port, the action of the sealing means is to reduce the amount of such gas permitted to enter the vacuum enclosure. For the purposes of the present invention, a condensible gas is defined as a gas which condenses under the temperature and pressure conditions present inside the vacuum chamber. A preferred condensible gas is steam.

Further in accordance with an embodiment of the present invention, the vacuum enclosure may define inlet and outlet ports, conduits associated therewith and first and second rotary feeders associated with the respective conduits and disposed within the vacuum enclosure.

The apparatus of the present invention has significant advantages over prior art designs of vacuum chambers wherein the rotary feeder is disposed outside the vacuum chamber. These advantages may be summarised as follows: (a) Obviates the need for a housing surrounding the rotary feeder; (b) Enables the rotary feeder to be maintained at a uniformly low temperature, which was not possible in the prior art due to the need to avoid condensation of the condensible gas; (c) Obviates the need for vacuum sealing at the axles of the feeder; (d) Enables simpler, lighter and less expensive construction to be used since smaller forces produced by the vacuum gradient are exerted thereon; (e) Reduces intake of atmospheric air to the vacuum enclosure; (f) Facilitates access in the case of jamming; (g) Enables continuous cleaning of the feeder.

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings, in which: Figure 1 is a side sectional illustration of a vacuum treatment chamber incorporating a rotary feeder constructed and operative in accordance with a preferred embodiment of the present invention; Figure 2 is a top sectional illustration of the apparatus of Figure 1, wherein the interior conveying apparatus has been omitted for clarity; Figure 3 is a side sectional illustration of a rotary feeder useful in a preferred embodiment of the present invention; and Figure 4 is a sectional illustration of the apparatus of Figure 3 taken along the lines A - A thereof.

Referring first to Figures 1 and 2, a vacuum treatment chamber, indicated generally by reference numeral 10 is constructed in a conventional manner and is suitable for maintaining a vacuum of about 28 mm Hg. The vacuum chamber may be of any suitable configuration and size and is preferably suitable for permitting manufacturing processes, such as can sealing, exhaustion of air from fruit tissues, etc. to be carried on therein.

Vacuum treatment chamber 10 is formed with an inlet port 12 and an outlet port 14 which permit ingress and egress of goods involved in a manufacturing process as well as a communications port 16, which communicates with a vacuum pump or other source of vacuum, for maintaining the desired vacuum in the interior of chamber 10.

As an alternative, only a single port may be provided and this port may serve as both an ingress and egress port. As a further alternative, more than two ports may be provided.

At least one rotary feeder is located within the vacuum chamber and is arranged for communication with a port thereof via a conduit and in the illustrated embodiment, two such rotary feeders 18 and 20 are located within the vacuum chamber 10.

Feeders 18 and 20 communicate with respective inlet and outlet ports 12 and 14 via respective feeder conduits 22 and 24 which communicate with the outside atmosphere. In order to minimise leakage of atmospheric air into the vacuum chamber 10, conduits 22 and 24 are filled, via supply conduits 26 with a condensible gas, such as steam, substantially to the exclusion of atmospheric air, whereby entry of the condensible gas into the vacuum chamber does not appreciably reduce the vacuum therein since the gas condenses under the temperature and pressure conditions of the inside of the vacuum chamber.

Articles or goods for treatment are supplied via conduit 22 to rotary feeder 18 by a conveyor 28, while treated articles or goods may be removed from rotary feeder 20 by gravity. Communication of goods within the vacuum chamber may be provided by any suitable materials handling means, which are illustrated for simplicity herein as conveyor belts 32.

According to one preferred embodiment of the invention, the rotary feeders 18 and 20 as well as the conveyors 32 are powered by power sources which are located within the vacuum chamber, such as pneumatic or hydraulic motors, which are coupled to a source of motive power, such as pressurised air or hydraulic fluid, via conduits 26 which pass through the walls of the vacuum chamber 10.

Referring now to Figures 3 and 4 which illustrate details of the feeders 18 and 20, it is seen that rotor 112 is of generally disc-like configuration and comprises a pair of parallel circular side walls 114 and 116 which are mounted on a driving shaft 118, which is in turn bearing mounted within vacuum chamber 10. It is appreciated that the mounting of shaft 118 in vacuum chamber 10 need not be a sealed mounting to minimise the amount of gas leakage as in the prior art, since the entire assembly is located within the vacuum chamber.

Rotor 112 also comprises an inner cylindrical wall surface extending between side walls 114 and 116 and a plurality of fins 122 extending radially outward therefrom so as to define sealed compartments 123, which are sized to contain articles such as cans 124 which are sought to be fed by the rotary feeder.

A sealing assembly 130 is associated with the inlet opening 128. The sealing assembly 130 comprises a generally arcuate sealing shoe 134, which is maintained in pressurised contact with the periphery of the rotor 112 by means of an elastic member 136, typically formed of a polymer, which is disposed between the inside surface of a flared portion 132 of the conduit and the outer facing surface of the sealing shoe 134.

The sealing shoe 134 is typically formed of a material which is softer than the material from which the rotor 112 is formed, such that rotation of the rotor 112 against the sealing shoe tends to cause wear in the sealing shoe, which is relatively readily replaceable. Normally grooves will develop in the sealing shoe, enhancing the sealing provided thereby.

The sealing shoe is configured to be larger than the outlet opening and to circumferentially surround it. The sealing assembly 130 may thus be understood to provide an effective fluid seal between the conduit 22 or 24 and the interior of vacuum chamber 10. Furthermore, the configuration of the shoe is such that a compartment of the rotor which is open to the outlet opening is sealed from the adjacent compartments which communicate with the interior of the vacuum chamber 10. In practice, at least two compartments 123 and three adjacent fins 122 are covered by shoe 134.

The operation of the rotary feeder described hereinabove will now be reviewed briefly. As seen in Figure 3, cans, or any other suitable objects or bulk materials, are loaded into the compartments 123, one can per compartment, and, by rotation of the feeder rotor, then reach interior of the vacuum processing chamber where they are transported by conventional automatic materials handling equipment. Similar operation occurs in reverse as the cans or other objects or material are unloaded by the feeder 20.

It will be appreciated that the present invention is not limited to the configuration of the chamber or the rotary feeder, which are here shown in an embodiment particularly suitable for loading of cans. The present invention is not limited by the particular structure shown and described hereinabove.

Claims

1. A vacuum treatment chamber comprising an enclpsure having means for maintaining the interior at predetermined vacuum and temperature conditions, and having at least one access port, a rotary feeder disposed within the enclosure and being maintained at the vacuum and temperature conditions of the interior thereof and communicating with the access port and sealing means coupled to the access port and arranged for sliding engagement with a relatively small portion of the periphery of the rotary feeder, for providing communication between the port and the rotary feeder.

2. Apparatus according to claim 1, wherein the remainder of the rotary feeder is open to the interior of the vacuum enclosure.

3. Apparatus according to claim 1 or claim 2 wherein the rotary feeder comprises a cylindrical rotor defining a plurality of peripheral compartments.

4. Apparatus according to claim 3 wherein the sealing means comprises a sealing shoe and an elastic element for urging the sealing shoe against the rotor.

5. Apparatus according to claim 4 wherein the sealing shoe is formed of a material which is softer than the material of the rotor, whereby frictional engagement therebetween produces wear in the sealing shoe.

6. Apparatus according to claim 4 or claim 5 wherein the sealing shoe extends peripherally of an inlet opening and prevents fluid communication from a compartment communicating with the opening and an adjacent compartment which communicates with the interior of the vacuum chamber.

7. A vacuum treatment chamber comprising an enclosure having means for maintaining the interior at predetermined vacuum and temperature conditions, and having at least one access port, a rotary feeder disposed within the enclosure and being maintained at the vacuum and temperature conditions of the interior thereof and communicat ing with the access port via a conduit capable of being filled with a condensible gas substantially to the exclusion of atmospheric air, and sealing means coupled to the conduit and arranged for sliding engagement with a relatively small portion of the periphery of the rotary feeder, for providing communication between the conduit and the rotary feeder while reducing the amount of condensible gas permitted to enter the vacuum enclosure.

8. Apparatus according to claim 7 and wherein the remainder of the rotary feeder is open to the interior of the vacuum enclosure.

9. Apparatus according to claim 7 or claim 8 wherein the rotary feeder comprises a cylindrical rotor defining a plurality of peripheral compartments, the sealing means associated with the rotor sealing the access port opening from the interior of the vacuum chamber.

10. Apparatus according to claim 9 wherein the sealing means comprises a sealing shoe and an elastic element for urging the sealing shoe against the rotor.

11. Apparatus according to claim 10 wherein the sealing shoe is formed of a material which is softer than the material of the rotor, whereby frictional engagement therebetween produces wear in the sealing shoe.

12. Apparatus according to claim 10 or claim 11 wherein the sealing shoe extends peripherally of an inlet opening and prevents fluid communication from a compartment communicating with the opening and an adjacent compartment which communicates with the interior of the vacuum chamber.