BAG HOLDING AND SEALING UNIT

Description

[0001] The present invention relates to a bag holding and sealing unit according to the preamble of claim 1.

[0002] Waste disposal bags, whether of paper or plastics material, are commonly presented for use by being suspended at their open upper ends from the rim of a free-standing bin or from a wall-mounted frame. The upper end of the bag is held open and the bin or frame may have a lid to cover the open end when the bag is not in use. When the bag is full, it can be closed at its upper end by a tie, adhesive tape or staples. Such a method of supporting and subsequently closing the bag is Satisfactory provided the lid adequately covers the bag and provided the final closing of the bag results in secure sealing. These considerations are of particular significance in the case of waste disposal bags for restaurants, hospitals and similar establishments where hygiene and sanitation are of paramount importance. In such cases, suspension of the bag from a lidded bin or frame and manual sealing of the filled bag may not be ideal.

[0003] In CH-A-538 401 there is described a bag holding unit in which a first bag holding member, with clips for releasably retaining one wall of a waste disposal bag, is fastened to inside walls of a cupboard and a second bag holding member, with clips for releasably retaining an opposite wall of the bag, is fastened to a bottom-hinged door of the cupboard. The door can move between first and second rest settings in which the bag upper end is respectively closed and open. The two members have co-operating rubber strips which clamp the bag walls together when the door is closed. This unit ensures that the bag is automatically closed when not needed for insertion of waste, but sealing of the filled bag must be carried out quite separately after release of the bag walls from the clips and extraction of the bag from the cupboard by lifting up over the door via a relatively narrow gap. This manoeuvre is awkward and there is a risk of spillage from the unsealed bag and, if the filled bag is very bulky, even tearing of the bag walls.

[0004] It is common practice, in the case of storage bags of heat weldable plastics material, to close the bag by heat sealing, that is to say fusing together strips of material of the bag walls by means of heat sufficient to melt the material. The resulting closure is permanent and hermetic. Equipment for sealing bags in this manner has been devised for use with food storage bags and to a lesser extent for use with waste disposal bags. In GB-A-1 037 576 and GB-A-1 081 045 there are disclosed bag holding and sealing units comprising a bag supporting structure with two relatively movable parts for removably suspending a bag by its mouth portion, the bag being opened and closed by relative movement of the parts. One of the parts, in particular a part intended to be mounted on a wall, incorporates a heat sealing element for sealing the bag mouth. The moving part of the structure is represented by a front cover (which in the case of the unit of GB-A-1 037 576 extends the full depth of the bag) spring-loaded into the closing position. In its open position, the front cover must be held against the closing force of the spring-loading and consequently the user has only one hand available for placing material into the bag. The absence of a rest setting of the front cover when the bag is open is inconvenient, especially for such actions as scraping waste materials into the bag.

[0005] A further disadvantage of these units relates to operation of the heating sealing device. Safety considerations require the device to be operable only under certain conditions and these are fulfilled by a relatively cumbersome arrangement of a locking lever which is swung forward to lock the movable front cover against the wall-mounted part of the structure. In its forward position the lever exposes a manually operable switch for the heat sealing device. Two separate actions, i.e. movement of the lever and operation of the switch, are required by the user in order to actuate the heat sealing device and the lever adds to the constructional cost and complexity of the unit. Moreover, the lever arrangement does not clearly satisfy safety requirements. It appears possible to move the lever and expose the switch for operation when the front cover is in its open position and thus when the heat sealing element might be able to be touched.

[0006] Yet another disadvantage in the case of the unit of GB-A-1 037 576 is the construction of the support structure as a complete housing for the bag. When the filled, and thus enlarged, bag is to be removed from the unit, the front cover has to be pivoted outwardly an extra distance after being lifted to clear a travel stop. The stop is incorporated in a convoluted guide slot for a guide stud of the cover. Exchange of a bag thus requires the user to pivot open the cover, lift the cover, open the cover further, hold the cover against the increased force of the spring-loading, disengage the bag from retaining pegs and lift the filled bag out of the unit. Manipulation of the unit for the bag changing is thus awkward. The cover itself is removable, but this entails disconnection of a spring which provides the spring-loading.

[0007] Also known, from EP-A-0 005 660, is a device for forming sealed packaging bags from a continuous tube. The device functions as part of automatic packaging equipment and requires preliminary loading with the tube in a compressed state. The tube is drawn downwardly section by section, with each section being sealed at its lower end before filling and sealed at its upper end after filling. The device produces bags, rather than works with bags, and incorporates complicated drive arrangements for advancing and sealing sections of the tube. Utilisation of the device is consequently limited to industrial packaging equipment.

[0008] The present invention has its principal object the provision of a bag holding and sealing unit which is relatively simple and convenient to use, in particular with respect to bag filling and sealing, and which is suitable for domestic, commercial or industrial use.

[0009] A supplementary object of the invention is to provide a bag sealing and holding unit which may be economic to manufacture and which is sturdy and compact.

[0010] Other objects and advantages of the invention will be apparent from the following description.

[0011] The principal object of the present invention is met by a bag holding and sealing unit having the features stated in the characterising part of claim 1.

[0012] Such a unit has open and closed rest settings from the movable second member, so that the user is not obliged to combat a spring-loading when the second member is in the setting in which the bag is held open. The pivot axis can be so disposed that the second member is locatable in each of the rest settings by gravity. Other methods can be used, however, for example an over-centre spring arrangement in which spring force draws the second member into either one of the rest settings but does not prevent it from freely remaining in the other rest setting. Even in the case of gravity location of the member in its open setting it may be advantageous to provide spring, cam or detent means to assist retention of the member in the closed setting and it is merely sufficient to ensure that the nature of any such assistance cannot alone overcome the gravity effect in the open setting.

[0013] A compact form of the unit is advantageously achieved if each of the members comprises a transverse head portion and two depending legs, with the pivot axis being disposed at the free ends of the legs. Lateral stability of the members relative to each other may be improved if the legs of one member are provided with guide blades and the legs of the other member with slots guiding the blades. The blades are for preference provided with abutments to determine the second rest setting of the second member.

[0014] The heat sealing means is preferably arranged on the first member and the resilient means preferably has the form of a strip of elastomeric material arranged on the second member. The resilient strip serves to both close the bag upper end in the first rest setting of the second member and oppose movement of the second member into the transient setting. The second member can thus remain in the transient setting for as long as it is pressed towards the first member by the user. The requirement for the user to maintain a small pressure on the second member in order for the actuating means to respond and actuate the heat sealing means represents a simple and safe method of ensuring that the user must be present and personally initiate and supervise the sealing procedure. When user pressure is removed, the resilient strip acts to move the second member out of the transient setting.

[0015] The heat sealing means itself preferably comprises an electrically heatable wire covered by a heat-resistant tape. The wire can be held at its ends by spring means arranged to compensate for thermally-induced change in the length of the wire.

[0016] For preference the actuating means comprises a switch to control operation of the heat sealing means. The switch can be a microswitch disposed on the first member, and the second member can be provided with a projection to actuate the microswitch in the transient setting of the second member. The actuating means preferably also comprises timing means, such as a bimetallic switch, to terminate operation of the heat sealing means after a predetermined period of time. Consequently, the heat sealing means will switch off even if the user maintains the second member in the transient setting for longer than actually necessary for sealing of the bag.

[0017] At least one of the first and second retaining means preferably comprises a plurality of spaced apart projections engageable in perforations provided at the upper end of the bag. These projections may each comprise a shank part and a head part of greater height than the shank part. The projections are, for preference, hooks. The bag itself preferably consists of thermally weldable material, such as thermoplastic plastics material. Alternatively, the bag can be simply provided at the upper ends of the inner faces of its two side walls with strips of thermally fusible material, such as an adhesive. The bag material in that case can be paper.

[0018] An embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1

is a perspective view of a bag holding and sealing unit embodying the invention, with the unit in the closed state;

Fig. 2

is a view similar to Fig. 1, but with the unit in the open state;

Fig. 3

is a partly sectional end view of the unit in the closed state and suspending an empty bag, which is also closed;

Fig. 4

is an end view similar to Fig. 3, but with the unit in the open state and the bag also open; and

Fig. 5

is a schematic view of heat sealing means of the unit and a block circuit diagram of associated actuating means.

[0019] Referring now to tee drawings there is shown a bag holding and sealing unit 10 which is particularly intended for waste disposal bags but which is equally suitable for packaging bags, that is to say bags for packaging foodstuffs, consumer goods and other articles.

[0020] The unit comprises a first or fixed bag holding member 11, which is intended to be mounted on a wall or other such surface and which for this purpose has a planar rear face, and a second or movable bag holding member 12, which is pivotably connected to the first member. The two members are injection-moulded plastics material components and each consist of an at least partly hollow transverse head portion and two hollow depending legs. The pivotable interconnection is provided at the free ends of the legs. In particular, the legs of the fixed member 11 are provided with brackets 13 which extend into the hollow spaces of the legs of the movable member 12 and are connected to those legs by coaxial pivot pins 14. The legs of the member 12 are in turn provided with rigid guide blades 15 which are slidably engaged in guide slots in the brackets 14. The interengagement of the blades and brackets provides stable lateral location of the movable member relative to the fixed member. The blades 15 have curved upper edges and are provided at the free ends of those edges with abutments 16 cooperable with the upper edges of the guide slots to limit movement of the member 12 in direction away from the member 11.

[0021] As shown more particularly in Figs. 3 and 4, the movable member 12 is movable relative to the fixed member 11 between a first or closed setting in which it is supported against the member 11 (Fig. 3) and a second or open setting in which it is pivoted out from the member 11 (Fig. 4) and arrested by the abutments 16. The pivot axis defined by the pivot pins 14 is so disposed relative to the centre of gravity of the movable member 12 that the member 12 locates in either setting simply by gravity, each of the two settings thus being a stable rest setting. The member 12 is addditionally movable between the closed rest setting and a transient setting which is spaced from the closed rest setting by a small distance D in direction away from the closed rest setting, thus closer to the member 11. The transient setting is unstable, as explained further below.

[0022] The movable member 12 is provided on the top of its head portion with a lip 17 serving as a handle for movement of the member 12, in particular from the closed to the open rest setting.

[0023] The transverse head portion of the fixed member 11 includes a protruding work face 18 with a row of three equidistantly spaced hooks 19 and the transverse head portion of the movable member 12 includes a recessed work face 20 with a row of three correspondingly spaced hooks 21. In the closed rest setting of the member 12, the two work faces 18 and 20 are disposed in close proximity to each other and each hook 19 is disposed at the same height as and directly opposite to a respective one of the hooks 21.

[0024] Each of the hooks 19 and 21 consists of a shank part and a head part of flattened teardrop shape, the head part being considerably higher than the shank part. The hooks serve for releasable retention of a bag 22 (Figs. 3 and 4) of thermoplastic plastics material, that is to say material that can be thermally welded. The bag shape is preferably, but not necessarily, elongate and with two major side walls joined together either directly or by way of gussets. The side walls can also be respective portions of a bag which, in fully opened state, is essentially tube-shaped. The bag is closed at its lower end and open at its upper end. Provided in each of the side walls, and at the upper end of the bag, are three perforations corresponding in disposition to each of the three rows of hooks and in shape to the hook shank part. Conveniently, each perforation has approximately the form of a slot which is horizontal in the bag position shown in Figs. 3 and 4. Such a bag is simply and easily attached to the members 11 and 12 by insertion of the head parts of the hooks 19 and 21 into corresponding ones of the perforations and pulling the bag down until the hook shank parts are seated in the perforations.

[0025] The head portion of the member 12 is further provided on its work face 20, and below the hooks 21, with a rubber strip 23 which is compressible in cross-section without excessive force. The strip 23 has two functions. Firstly, it acts as a pressure and support element to support the movable member 12 relative to the fixed member 11 when the former is in the closed rest setting and, in this setting, to press the bag walls together as shown in Fig. 3. Secondly, the strip 23 provides a spring force which opposes movement of the member 12, by user pressure, from the closed rest setting into the transient rest setting and which returns the member 12 into the closed rest setting when pressure on the member 12 is released.

[0026] The head portion of the member 11 is further provided on its work face 18, and below the hooks 19, with a heat sealing element 24 for sealing together the walls of the bag. The element has the form of a hot wire 25 sandwiched between two tapes 26 of heat-resistant material, such as woven glass-fibre. The tape facing outwardly of the work face 18 is preferably impregnated with a low-friction substance, for example polytetrafluoroethylene. The element 24, in particular the wire 25, is aligned with the rubber strip 23 in the closed rest setting of the member 12 as shown in Fig. 3, the walls of the bag 22 thus being pressed by the strip 23 against the element 24. As shown in Fig. 5, the wire 26 is connected at its ends to electrically conductive terminal yokes 27 by way of electrically conductive tension springs, which compensate for thermally-induced change in the length of the wire and keep it taut at all times. The yokes 27 locate in slots in the member 11 and act as heat sinks, so that current supply cables connected thereto can be of low temperature rating.

[0027] The interior space of the head portion of the member 11 houses electrical actuating means for the heat sealing element, the actuating means comprising a transformer 28 connected between the hot wire 25 and mains terminals, a microswitch 29 between the transformer and the mains terminals, and a bimetallic switch 30 and indicator lamp 31 in series with the wire 25. The microswitch 29 is disposed in a depression in the work face 18 of the member 11 and is operable by a projection 32 on the work face 20 of the member 12. Operation of the microswitch 29 by the projection 32 takes place only in the transient setting of the member 12; in the closed rest setting of the member, the microswitch is unactuated.

[0028] When the microswitch is actuated, current heats the wire 25 and the bimetallic strip of the bimetallic switch 30 and illuminates the lamp 31. The switch 30 responds after a preset time, for example about five seconds, and terminates current supply to the wire 25 and the lamp 31. The lamp thus provides both a warning that the heat sealing element is in operation and an indication when the operation is terminated. Operation can also be terminated in advance of the preset time simply by allowing the member 12 to return to the first rest setting and thus release the microswitch.

[0029] In use of the unit 10, the fixed member 11 is attached to, for example, a wall by means of screws or other fastening devices extending in suitable openings in the member 11. With the movable member 12 in the open rest setting a bag 22 is attached to the unit by insertion of the hooks 19 and 21 into the perforations in the bag side walls in the manner previously described. The bag can be filled while the member 12 is in the open rest setting. When the bag is not in use, the member 12 is moved into the closed rest setting so that the bag is kept closed by the strip 23 under the weight of the member 12 together with, if considered desirable, a spring-loaded detent (not shown) releasably securing the members 11 and 12 together. Closure of the bag ensures that there is no escape of odour in the event that the bag is used for waste disposal.

[0030] When the bag is filled to the required degree it is permanently sealed at its upper end by means of the heat sealing element 24. With the actuating means terminals connected to a mains supply, for example by way of a plug, the user presses the movable member 12 from the closed rest setting into the transient setting. The microswitch 29 is thus actuated as previously described and the heat sealing element 24 energised and lamp 31 illuminated. The heat of the element 24 fuses together the material of the two side walls of the bag to form a welded seam. At the conclusion of the preset sealing time, the bimetallic switch 30 switches off the sealing element and lamp and the user can release pressure on the member 12 so that it is returned to the closed rest setting by the resilience of the strip 23. The sealed bag, which by virtue of the sealing operation is separated or readily separable from the bag portions with the perforations, can now be removed and the member 12 moved into its open rest setting, with the perforated bag portions also being removed from the hooks. The unit is now ready to receive a fresh bag 22.

[0031] The bag holding and sealing unit is simple and convenient to use and the bag can be left in an open state or a closed state as desired and without the need to maintain the open state against a spring return. Operation of the heat sealing means is by way of a small pressure on the movable member 12 and the control switching and timing incorporated in the actuating system ensure security against the possibility of accidental touching of the heating sealing element when in operation and prevent operation of the element for longer than necessary. The location of the microswitch 29 in a depression can be such that operation of the microswitch is not readily possible except by way of the projection 32 and the microswitch will normally be concealed by a wall of a bag even when the member 12 is in its open setting.

Claims

1. A bag holding and sealing unit (10) comprising a first bag holding member (11) for mounting on a substantially vertical surface and provided with first retaining means (19) for releasably retaining one of two mutually opposite side walls of a bag (22) open at its upper end, and a second bag holding member (12) mounted on the first member (11) to be pivotable relative thereto about a pivot axis and provided with second retaining means (21) for releasably retaining the other one of said side walls of the bag (22), the second member (12) being movable between a first rest setting in which the upper end of the bag when retained by the first and second retaining means (19, 21) is kept closed by the members and a second rest setting in which the upper end of the bag is held open by the members, characterised in that the second member (12) is additionally movable between the first rest setting and a transient setting which is spaced from the first rest setting in direction away from the second rest setting and in which the upper end of the bag (22) remains closed, and that the unit further comprises resilient means (23) to press the bag walls against each other in the first rest setting of the bag and to return the second member (12) from the transient setting to the first rest setting, heat sealing means (24) arranged at one of the members and operable to fuse together fusible material of or on said side walls of the bag at its upper end, and actuating means (29, 32) responsive to the transient setting of the second member to actuate the heat sealing means.

2. Unit as claimed in claim 1, characterised in that the pivot axis is so disposed that in use the second member (12) is locatable in each of the rest settings by gravity.

3. A unit as claimed in either claim 1 or claim 2, characterised in that each of the members (11, 12) comprises a transverse head portion and two depending legs, the pivot axis being disposed at the free ends of the legs.

4. A unit as claimed in claim 3, characterised in that the legs of one (12) of the members are provided with guide blades (15) and the legs of the other one (11) of the members are provided with slots guiding the blades.

5. A unit as claimed in claim 4, characterised in that the blades (15), are provided with abutments (16) to determine the second rest setting of the second member (12).

6. A unit as claimed in any one of the preceding claims, characterised in that the second member (12) is provided with a lip (17) serving as a handle.

7. A unit as claimed in any one of the preceding claims, characterised in that the heat sealing means (24) is arranged on the first member (11) and the resilient means (23) comprises a strip of elastomeric material on the second member (12).

8. A unit as claimed in any one of the preceding claims, characterised in that the heat sealing means (24) comprises an electrically heatable wire (25) covered by a heat-resistant tape (26).

9. A unit as claimed in claim 8, characterised in that the wire (25) is held at its ends by spring means arranged to compensate for thermally-induced change in the length of the wire (25).

10. A unit as claimed in any one of the preceding claims, characterised in that the actuating means (29, 32) comprises a switch (29) to control operation of the heat sealing means.

11. A unit as claimed in claim 10, characterised in that the switch (29) is a microswitch disposed on the first member (11) and the second member (12) is provided with a projection (32) to actuate the microswitch in the transient setting of the second member (12).

12. A unit as claimed in any one of the preceding claims, characterised in that the actuating means (29, 32) comprises timing means to terminate operation of the heat sealing means after a predetermined period of time.

13. A unit as claimed in claim 12, characterised in that the timing means comprises a bimetallic switch (30).

14. A unit as claimed in any one of the preceding claims, characterised in that at least one of the first and second retaining means (19, 21) comprises a plurality of spaced apart projections engageable in perforations provided at the upper end of the bag.

15. A unit as claimed in claim 14, characterised in that each of the projections comprises a shank part and a head part of greater height than the shank part.

16. A unit as claimed in claim 15, characterised in that the projections are hooks.

Ansprüche

1. Ein Beutelhalte- und schweissgerät (10), das ein erstes Beutelhalteglied (11), das zur Montage auf einer hauptsächlich vertikalen Fläche bestimmt ist und mit erstem Haltemittel (19) zum Halten und Freigeben einer zwei einander gegenüberliegenden Seitenwände eines an seinem oberen Ende geöffneten Beutels (22) versehen ist, und ein zweites Beutelhalteglied (12) ausweist, das so am ersten Glied (11) montiert ist, dass es relativ hierzu um eine Schwenkachse schwenkbar ist, und das mit zweitem Haltemittel (21) zum Halten und Frei geben der anderen gesagten Seitenwand des Beutels (22) versehen ist, wobei das zweite Halteglied (12) zwischen einer ersten Ruhestellung, in der das obere Beutelende von den Gliedern geschlossen wird, wenn es von den ersten und zweiten Haltemitteln (19, 21) gehalten wird, und einer zweiten Ruhestellung, in der das obere Beutelende von den Gliedern offen gehalten wird, bewegbar ist, dadurch gekennzeichnet wird, dass sich das zweite Glied (12) zusätzlich zwischen der ersten Ruhestellung und einer Übergangsstellung bewegen lässt, die sich von der ersten Ruhestellung in Richtung von der zweiten Ruhestellung weg befindet, und bei der das obere Beutelende (22) geschlossen bleibt, und dass das Gerät desweiteren Rückfederungsmittel (23) zum Aneinanderdrücken der Beutelwände in der ersten Ruhestellung des Beutels und zur Rückkehr des zweiten Glieds (12) aus der Übergangsstellung in die erste Ruhestellung, Heissiegelmittel (24), die an einem der Glieder angeordnet sind und schmelzbare Materialien von oder an den besagten Seidenwänden des oberen Beutelendes zusammenschmelzen, und Betätigungsmittel (29, 32), die auf die Übergangsstellung des zweiten Glieds reagieren, um die Heissiegelmittel zu betätigen, aufweist.

2. Gerät nach Anspruch 1, dadurch gekennzeichnet, dass die Schwenkachse so angeordnet ist, dass bei der Benutzung das zweite Glied (12) in beiden Ruhestellungen durch Schwerkraft gehalten werden kann.

3. Ein Gerät nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, dass jedes Glied (11, 12) einen Transversalkopfteil und zwei davon abhängige Stützen umfasst und die Schwenkachse sich am freien Ende der Stützen befindet.

4. Ein Gerät nach Anspruch 3, dadurch gekennzeichnet, dass die Stützen eines (12) der Glieder mit Leitschaufeln (15) versehen sind und die Stützen des anderen (11) Glieds mit Schlitzen versehen sind, die die Schaufeln führen.

5. Ein Gerät nach Anspruch 4, dadurch gekennzeichnet, dass die Schaufeln (15) mit Anschlägen (16) versehen sind, um die zweite Ruhestellung des zweiten Glieds (12) festzulegen.

6. Ein Gerät nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das zweite Glied (12) mit einem als Griff dienenden Rand (17) versehen ist.

7. Ein Gerät nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass sich das Heissiegelmittel (24) am ersten Glied (11) befindet und das Rückfederungsmittel (23) einen am zweiten Glied (12) angeordneten Streifen aus elastischem Polymer umfasst.

8. Ein Gerät nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Heissiegelmittel (24) einen elektrisch erhitzbaren Draht (25) umfasst, der durch ein hitzebeständiges Band (26) abgedeckt ist.

9. Ein Gerät nach Anspruch 8, dadurch gekennzeichnet, dass der Draht (25) an den Enden von Federmitteln gehalten wird, um die von der Wärme hervorgerufene Veränderung der Länge des Drahts (25) auszugleichen.

10. Ein Gerät nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Betätigungsmittel (29, 32) einen Schalter (29) zur Steuerung des Betriebs des Heissiegelmittels umfasst.

11. Ein Gerät nach Anspruch 10, dadurch gekennzeichnet, dass der Schalter (29) ein Mikroschalter ist, der sich am ersten Glied (11) befindet, und dass das zweite Glied (12) mit einem Ansatz (32) versehen ist, um den Mikroschalter in der Übergangsstellung des zweiten Glieds (12) zu betätigen.

12. Ein Gerät nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Betätigungsmittel (29, 32) ein Zeitglied zur Beendigung des Betriebs des Heissiegelmittels nach einer vorbestimmten Zeitdauer umfasst.

13. Ein Gerät nach Anspruch 12, dadurch gekennzeichnet, dass das Zeitglied einen bimetallischen Schalter (30) aufweist.

14. Ein Gerät nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass wenigstens eines der ersten und zweiten Haltemittel (19, 21) eine Vielzahl von Ansätzen mit einem gewissen Abstand zueinander besitzt, die in Perforierungen am oberen Beutelende eingreifbar sind.

15. Ein Gerät nach Anspruch 14, dadurch gekennzeichnet, dass jeder der Ansätze einen Schaftteil und einen Kopfteil umfasst, wobei der Kopfteil höher ist als der Schaftteil.

16. Ein Gerät nach Anspruch 15, dadurch gekennzeichnet, dass die Ansätze Haken sind.

Revendications

1. Unité de maintien et de formation d'un joint hermétique de sac (10) comprenant un premier élément de maintien de sac (11) qui se monte sur une surface essentiellement verticale et qui comporte un premier moyen de fixation (19) pour maintenir de manière amovible une des deux parois latérales opposées l'une à l'autre d'un sac (22) ouvert à sa partie supérieure, et un second élément de maintien de sac (12) monté sur le premier élément de maintien (11) et qui peut pivoter par rapport à ce premier élément de maintien (11) autour d'un axe de pivot et qui comporte un second moyen de maintien (21) pour retenir de manière amovible la seconde des parois latérales du sac (22), le second élément de maintien (12) pouvant se déplacer entre une première position de repos à laquelle l'extrémité supérieure du sac est maintenue fermée par les éléments de maintien lorsque cette extrémité supérieure est maintenue par le premier et le second moyen de maintien (19, 21) et une seconde position de repos à laquelle l'extrémité supérieure du sac est maintenue ouverte par les éléments de maintien, cette unité étant caractérisée par le fait que le second élément de maintien (12) peut en outre se déplacer entre la première position de repos et une positon transitoire située à distance de la première position de repos en s'éloignant de la seconde position de repos et à laquelle l'extrémité supérieure du sac (22) reste fermée, et par le fait que cette unité comprend en outre un moyen élastique (23) pour appuyer les parois du sac l'une contre l'autre dans la première position de repos du sac et pour renvoyer le second élément de maintien (12) de la position transitoire à la première position de repos, un moyen de formation d'un joint hermétique thermique (24) aménagé au niveau de l'un des éléments de maintien et qu'on manoeuvre pour faire fusionner ensemble le matériau fusible de la partie supérieure des parois du sac ou sur la partie supérieure de ces parois et un moyen d'actionnement (29, 32) qui répond à la position transitoire du second élément de maintien (12) pour actionner le moyen de formation d'un joint hermétique thermique.

2. Unité selon la revendication 1, caractérisée par le fait que l'axe de pivot est placé de manière à ce que pendant l'utilisation le second élément de maintien (12) puisse se loger par gravité dans chacune des positions de repos.

3. Unité selon la revendication 1 ou la revendication 2, caractérisée par le fait que chacun des éléments de maintien (11, 12) est constitué par une partie tète transversale et deux jambes dépendantes, l'axe de pivot étant placé à l'extrémité libre de ces jambes.

4. Unité selon la revendication 3, caractérisée par le fait que les jambes de l'élément de maintien (11) comporte des lames de guidage (15) et que les jambes de l'autre élément de maintien (12) comportent des rainures pour guider les lames.

5. Unité selon la revendication 4, caractérisée par le fait que les lames (15) comportent des butées (16) pour déterminer la seconde position de repos du second élément (12).

6. Unité selon l'une quelconque des revendications qui précèdent, caractérisée par le fait que le second élément de maintien (12) comporte un rebord (17) qui sert de poignée.

7. Unité selon l'une quelconque des revendications ci-dessus, caractérisée par le fait que le moyen de formation d'un joint hermétique thermique (24) est aménagé sur le premier élément de maintien (11) et que le moyen élastique (23) est constitué par une bande en matériau élastomère sur le second élément de maintien (12).

8. Unité selon l'une quelconque des revendications précédentes, caractérisée par le fait que le moyen de formation d'un joint hermétique thermique (24) est constitué par un fil qui peut être chauffé thermiquement (25) recouvert par une bande résistant à la chaleur (26).

9. Unité selon la revendication 8, caractérisée par le fait que le fil (25) est maintenu à chacune de ses extrémités par un moyen à ressort aménagé pour compenser la variation de longueur du fil (25) provoquée par la chaleur.

10. Unité selon l'une quelconque des revendications précédentes, caractérisée par le fait que le moyen d'actionnement (29, 32) est constitué par un commutateur (29) pour commander le fonctionnement du moyen de formation d'un joint hermétique thermique.

11. Unité selon la revendication 10, caractérisée par le fait que le commutateur (29) est un microcontact placé sur le premier élément de maintien (11) et par le fait que le second élément de maintien (12) comporte une saillie (32) pour actionner le microcontact dans la position transitoire du second élément de maintien (12).

12. Unité selon l'une quelconque des revendications précédentes, caractérisée par le fait que le moyen d'actionnement (29, 32) est constitué par un moyen de temporisation pour interrompre le fonctionnement du moyen de formation d'un joint hermétique thermique après un temps déterminé.

13. Unité selon la revendication 12, caractérisée par le fait que le moyen de temporisation est constitué par un commutateur bilame (30).

14. Unité selon l'une quelconque des revendications précédentes, caractérisée par le fait qu'au moins le premier des deux moyens de maintien (19, 21) est constitué par une pluralité de saillies distantes les unes des autres qui s'engagent dans des perforations disposées à la partie supérieure du sac.

15. Unité selon la revendication 14, caractérisée par le fait que chacune des saillies est constituée par une partie tige et une partie tête dont la hauteur est plus grande que celle de la partie tige.

16. Unité de maintien et de formation d'un joint hermétique de sac essentiellement comme décrit ci-dessus en rapport avec les dessins ci-joint.

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