WO1993024375A1

WO1993024375A1 - Device for packing products, especially food products, in gastight bags, such as plastic bags

Info

Publication number: WO1993024375A1
Application number: PCT/SE1993/000435
Authority: WO
Inventors: Holger Johnsson
Original assignee: Na Eriksson AB
Current assignee: Na Eriksson AB
Priority date: 1992-05-22
Filing date: 1993-05-18
Publication date: 1993-12-09
Anticipated expiration: 1994-11-22
Also published as: SE9201620L; AU4099393A; SE9201620D0; SE469936B

Abstract

A device for packing e.g. food products in gastight plastic bags comprises a head (5) on which the open end (3) of the bag (1) can be applied and retained in sealing manner, and means (21, 22) for first drawing air out of the bag and then blowing a protective gas into the bag. An axially reciprocating tube (9) is arranged in a passage (7) formed in the head (5) for conducting air to a vacuum pump (21) and protective gas from a supply (22). At a free end, the tube (9) carries a nozzle member (12) which, owing to the mobility of the tube, can be pressed against a product (2) contained in the bag when air is drawn out of the bag, thereby to ensure that air is drawn also from the immediate vicinity of the product. The nozzle member is in the form of a rod-shaped body (12) which, on the front side to be pressed against the product, has a crenellation with alternating projections (14) and indentations (15), at least some of the indentations being provided with nozzles.

Description

DEVICE FOR PACKING PRODUCTS, ESPECIALLY FOOD PRODUCTS, IN GASTIGHT BAGS, SUCH AS PLASTIC BAGS

Field of the Invention This invention relates to a device for packing pro¬ ducts, especially food products, in gastight bags, such as plastic bags, comprising a head on which the open end of the bag can be applied and retained in sealing manner, and means for first drawing air out of the bag and then blow- ing a protective gas into the bag, an axially reciprocat¬ ing tube being arranged in a passage formed in the head for conducting air to a vacuum pump and protective gas from a supply, said tube carrying, at a free end, a nozzle member which, owing to the mobility of the tube, can be pressed against a product contained in the bag when air is drawn out of the bag, thereby to ensure that air is drawn also from the immediate vicinity of the product. Background of the Invention

In many known packing devices, a nozzle through which the air is drawn out and the protective gas is blown in, is fixedly mounted in the application head. In practice, such a fixed nozzle arrangement is, however, ineffective when it comes to drawing air out of the bag. This incon¬ venience is especially pronounced when the product, e.g. a piece of meat, is small in relation to the bag. If so, the upper bag end connected to the application head is often flattened immediately after the suction of air has begun, and is sealed so tight that no air can be drawn from the vicinity of the product in the lower portion of the bag.

In an attempt at remedying this inconvenience, US 3,939,624 teaches a device in which a tube provided with a nozzle member at its free end is introduced into the bag and applied against the product contained therein. In this case, however, the nozzle member is in the form of simple holes made in the circumferential surface of the tube. These holes ensure effective evacuation of air only in the immediate vicinity of the tube. Summary of the Invention

The present invention aims at obviating the drawback impairing the packing device known from US 3,939,624. Thus, a basic object of the invention is to provide a device ensuring effective drawing of air, regardless of the shape and size of the product or products contained in the bag. Another object is to provide a device enabling the required protective gas to be rapidly and expediently blown into the bag after the air has been effectively drawn out, the device being inexpensive and of simple design.

According to the invention, these objects are achiev- ed by a device presenting the features recited in the characterising clause of the appended claim. Brief Description of the Drawing

In the drawing, FIG. 1 is a schematic view of the inventive device when drawing air out of a bag; and

FIG. 2 is a similar view of the inventive device when blowing protective gas into the bag. Description of a Preferred Embodiment

In the drawing, reference numeral 1 generally desig- nates a bag, preferably made of plastic, such as polyethy¬ lene plastic, in which a product 2 is to be packed. This product may be any optional food product, such as a piece of meat, but other products are also conceivable. Thus, the inventive device can also be used for sterile packing of surgical instruments and other instruments. The upper, open end of the bag is designated 3, while the closed lower portion is designated 4.

As schematically illustrated, the device comprises a head which is generally designated 5 and on which the open end 3 of the bag can be applied in sealing manner, more precisely with the aid of a sealing means 6. In actual practice, the sealing means can be a U-shaped frame press- ed against one side of the head, while at the same time the opposite side of the head is contacted with an under¬ lying structure.

A first passage 7 is formed in the head 5 and con- sists of a through channel communicating with a second through passage or channel 8. In the first passage 7, there is provided an axially reciprocating tube 9 ending in, or connected to, a stem 10 carrying a handle 11 at its free end. At the free end opposite to the handle, the tube 9 has a nozzle member, generally designated 12, provided with a plurality of small nozzles through which gas can pass into as well as out of the interior of the nozzle member, in turn communicating with the internal cavity 13 of the tube 9. The nozzle member 12 is in the form of an elongated or rod-shaped body extending transversely of the axial extent of the tube and having, on the front side facing away from the head, a crenellation with alternating projections 14 and indentations 15. In actual practice, the nozzles are positioned at the bottoms of at least some of the indentations 15 and are advantageously placed also on the back of the nozzle member, as clearly illustrated in the drawing. The tube 9 is guided by a bushing or washer 16 at one end of the channel 7, and by a sealing ring 17 at the opposite end of the channel. Adjacent to the sealing ring 17, there is further provided a bellows 18 for sealing the tube when the nozzle member 12 is retracted to an initial position, indicated by dash-dot lines, in which transverse holes 19 in the tubular wall have passed the sealing ring 17. The transverse holes 19 enable communication between the interior 13 and the out¬ side of the tube, more precisely so as to permit air to be drawn out, and protective gas to be blown in, through the passage 8.

A vacuum pump 21 is connected to the second passage 8 via a non-return valve 20. Also, a bottle or some other supply 22 of protective gas is connected to the passage 8. The protective gas may be of known or optional type, e.g. carbon dioxide or nitrogen. Adjacent to the bottle 22 containing protective gas, there is provided a pressure- reducing valve 23 for reducing the pressure of the gas in

2 the bottle to a low level, e.g. 1 kg per cm , as well as a shut-off valve 24 controlling the supply of protective gas to the application head. Opening and closure of the valve 24 are controlled by a sensor 25, which acts on a rocker arm 26 or the like provided on the valve. Operation of the Invention The inventive device operates as follows. In a first step, illustrated in Fig. 1, the open end 3 of the bag 1 is applied on the head 5 in sealing manner with the aid of the sealing means 6. Then, the nozzle member 12 is con¬ tacted with the product 2 contained in the bag, more pre- cisely by the tube 9 being axially displaced in relation to the passage 7 by manual operation of the handle 11. When the crenellation 14, 15 of the nozzle member 12 has been pressed against the product, the vacuum pump 21 is activated and draws the air out of the bag. The air is effectively drawn out, not only from the upper portion of the bag, but also from the immediate vicinity of the pro¬ duct which because of its comparatively small size is located in the lower portion of the bag. Obviously, the air is effectively drawn out regardless of the size of the product, since the nozzle member can always be contacted with the product.

Once the air has been evacuated from the bag, the vacuum pump 21 is switched off, and the shut-off valve 24 for the protective-gas bottle 22 is opened, letting pro- tective gas flow into the bag through the passage 8, the holes 19, the tubular channel 13 and the nozzles in the nozzle member 12. The protective gas is supplied at such a low pressure it is unable to open the non-return valve 20 against the action of a mechanical spring provided there- in. When a certain amount of protective gas has been sup¬ plied to the bag, the latter has expanded to a sufficient extent to act on the sensor 25. Then, the sensor closes the valve 24, interrupting the supply of protective gas. During or after such supply of protective gas, the nozzle member 12 is returned to the initial position illustrated by dash-dot lines. The packing operation is concluded by sealing the bag by a weld 27 in the area between the pro¬ duct 2 contained in the bag and the nozzle member 12 retracted to the initial position.

Claims

1. A device for packing products, especially food products, in gastight bags, such as plastic bags, com¬ prising a head (5) on which the open end (3) of the bag (1) can be applied and retained in sealing manner, and means (21, 22) for first drawing air out of the bag and then blowing protective gas into the bag, an axially reciprocating tube (9) being arranged in a passage (7) formed in the head (5) for conducting air to a vacuum pump (21) and protective gas from a supply (22), said tube car¬ rying, at a free end, a nozzle member (12) which, owing to the mobility of the tube, can be pressed against a product (2) contained in the bag when air is drawn out of the bag, thereby to ensure that air is drawn also from the imme¬ diate vicinity of the product, c h a r a c t e r i s ¬ e d in that the nozzle member is in the form of an elon¬ gated or rod-shaped body (12) extending transversely of the axial extent of the tube (9) and having, on the front side to be pressed against the product, a crenellation with alternating projections (14) and indentations (15), at least some of the indentations being provided with nozzles.