Cartridge assembly for the use of an invertible package

Abstract: The cartridge assembly for dispensing at least one component comprises a cartridge having a rigid cartridge cylinder (16), a package assembly (1) having a membrane (3) containing liquid chemical (2), the membrane having a closed inlet end (12) and an outlet end (8) and a piston assembly (10) disposed in said cartridge assembly. The piston side end (27) of the inner wall (16A) of the cartridge cylinder and the front (9) of said piston assembly are formed thus that the membrane (3) is turned "outside in" within itself by the action of the piston provided with a sealing lip (11) such that the inner surfaces of the turned "outside in" wall portions (3A, 3B) of the membrane are sliding relative to each other during emptying of the package, sealing the gap betweeen the double walls (3A, 3B). Such a device requires considerably less dispensing force which is important particularly for a hand driven apparatus, and allows an efficient sealing of the liquid while dispensing.

Description: The present invention refers to a cartridge assembly according to the introduction of independent claim 1. Such a cartridge assembly is known from EP-A-369 723 disclosing a package assembly where the membrane is turned "outside in" by a relatively short plunger, rather than being scraped off the wall under pressure and compacted, which considerably increases the relative mechanical efficiency, but causes sealing problems. This prior art assembly being used for dispensing custard, whipped cream or grease the sealing problems have not been recognised and also not that a leak path of the package content exists between the two adjacent membrane walls. The short plunger prohibites the use of chemicals used in industry, which can be very aggressive and have a very difficult to seal viscosity. Therefore, dependant upon viscosity of the liquid chemical content, the pressure being applied in order to dispense the content and the size of leak path, the effect can be to discharge part of the content of the membrane rearwards past the plunger instead of ahead of the plunger and out of the package, thus disturbing the ratio and increasing waste. This rearwards discharge is the result of leak between the two package membranes adjacent to the plunger and into the trailing membrane package behind the plunger where it will inflate, and may burst, the membrane under pressure. EP-A-0 693 437 to the same applicant discloses in one embodiment a liner, which is fastened at the outlet end to the cartridge wall and at the other end to the outside end of the piston, thus that by the action of the piston the liner is turned outside in. The piston is provided with a sealing lip. This construction needs a specific liner to be attached to the cartridge wall and to the piston and detached therefrom. The use of a thin wall plastic film or plastic film/metal foil laminate membrane sausage shaped package to contain and to dispense a chemical such as an adhesive or sealant is well known such as disclosed in EP-A-666 823 in that it is placed within a cartridge type container which acts as a mechanical support while the membrane is scraped off the cartridge wall and compacted to expell its content, the cartridge type container being re-usable. This above mentioned principle of compacting the package requires a much greater dispensing force in relation to a conventional cartridge due to the force required for scraping off and progressively compacting the foil package from the supporting inner cartridge wall while the package is under significant hydraulic pressure. This issue of force is very important especially for manually actuated dispensing devices where only a limited hand force is available. Based upon this prior art, the object of this invention is to provide for a cartridge assembly which can use conventional sausage type bags and offers a better sealing thus that no material can leak out beyond the rear of the piston. This object is attained by the cartridge assembly according to independent claim 1. Further embodiments and improvements are defined in the dependent claims. The invention will be explained in more detail hereinafter with reference to drawings of embodiments. Fig. 1A shows a longitudinal section of a first embodiment of the invention, Fig. 1B shows a variant to the embodiment of Fig. 1A, Figs. 2A and 2B show a longitudinal section of an assembly of the invention with two identical packages of Fig. 1 in different positions within a cartridge, Fig. 3 shows a variant of the rear part of the embodiment of Fig 2A. Fig. 3A shows a detail of the inlet end of the cartridge, Fig. 4 shows a longitudinal section of a variant of the embodiment of Fig. 1, Fig. 5A shows a longitudinal section of a package of a second embodiment of the invention, and Fig. 5B shows a longitudinal section of an assembly of the second embodiment of the invention, The proposed invention, using a piston with a pressure activated sealing lip, offers a considerable improvement over the prior art method of use of a thin membrane sausage type package where the membrane is not scraped off, collapsed and compacted by the front edge of a plunger while under considerable and adverse hydraulic pressure but instead, the package is progressively emptied and turned "outside in" within itself by the piston as it is driven towards the outlet side of the cartridge. As it does so, the membrane of the package is free to be progressively peeled off from the inner wall of the cartridge cylinder behind the piston where no adverse hydraulic pressure exists and is turned over "outside in" and trailed behind the piston. Typical operating backpressures of ten bars or more within the package ensure that the membrane does not slide within the cartridge inner wall and, as part of its function, the piston ensures a seal between the innermost membrane wall and the cartridge inner wall supported outermost membrane wall after the package is turned "outside in" within itself. Therefore, while using the principle of a membrane package structure with the prior art advantages of low disposal volume and weight, the proposed invention substantially reduces the dispensing force because the two adjacent material lubricated membrane wall portions, which are subjected to a sealing force provided by a sealing means in the form of the lip of the piston, slide easily relative to each other. Also, there is less material residue after use and the principle allows the repeated re-use of the rigid cartridge tube and the front outlet of the cartridge assembly. In both piston embodiments as above, the withdrawal of the piston from the partially used package requires that, at the time of withdrawal, a vacuum relief passage allows air to pass through to between the piston and the package so as to prevent a vacuum from forming and so as to allow the piston to withdraw and the package to remain. The invention pertains to a cartridge assembly with one cylinder and one package assembly as well as to a cartridge assembly with two or more cylinders having package assemblies with one common cartridge outlet receiving, sealingly, the package outlet adaptors. The invention is now explained in detail. Fig. 1A shows a longitudinal section of a sausage type thin wall membrane package assembly 1 containing a liquid chemical 2 and comprising a thin, strong and chemical resistant flexible plastic film or plastic film/ metal foil laminate membrane 3. The membrane 3 is folded and sealed by a crimped ring 8 and is attached by an adhesive to the content side face of the outlet adaptor 4, the latter having an outlet 5 with two sealing lips 6 and 7 on its outer diameter. The crimped ring 8 sealed end passes through the outlet adaptor 4. At the opposite and rear end of the package assembly 1, the membrane 3 is folded and sealed by a crimped ring 12 and is being held against the front face 9 of a driven piston 10, having a vacuum relief passage 71 and a female contour 19 comprising a flexible lip 11, by an adhesive such as hot melt 14 while said closed end with crimped ring 12 is positioned and held in a bore 13 within the driven piston 10. Fig. 1B shows a package assembly 1 within a cylinder 16, the package assembly 1 being similar to that shown in Fig. 1A but with the difference that the driven piston 72 has no female contour but a flat face 73 opposing the outlet adaptor 74, having a flat face 73A. Figs. 2A and 2B show a longitudinal section of a re-usable cartridge assembly 15 comprising two re-usable pressure resistant cylinders 16 and a common re-usable cartridge outlet 17 within which two identical package assemblies 1 containing liquid chemicals are positioned as shown in Fig. 1 in two different stages of dispensing. Fig. 2A shows the package assembly 1 just prior to dispensing, with the membrane 3 snugly fitting within the cartridge assembly 15, where the outlet adaptor 4 is positioned and sealed by the two lips 6 and 7, within a tapered bore 39 of the cartridge outlet 17, the front crimped ring 8 having been cut away so as to open the package. Support of the cartridge outlet 17 against forward thrust of the package assembly is not shown. A drive plunger 18 with a vacuum relief passage 71 and with drive rod 20 is shown at the rear of the package assembly 1 with the package under initial pressure via driven piston 10, the membrane 3 now following the inside female contour 19 of the driven piston 10 and its flexible lip 11. Fig. 2B shows the same components as in Fig. 2A but with the drive rod 20 and drive plunger 18 having moved the driven piston 10 forward approximately halfway down the package assembly 1. The membrane 3 is under hydraulic pressure against the inside of the flexible lip 11 of the driven piston 10 and presses that lip 11 and the two thus formed material-side membrane wall portions 3A and 3B against the cylinder inside wall 16A to form a seal between the two material lubricated inner surfaces of the membrane wall portions 3A and 3B in order to prevent the liquid chemical 2 leaking past that seal. During the dispensing operation, the membrane wall portion 3B slides relatively to the stationary membrane wall portion 3A. In Figs. 2A and 2B the cartridge cylinder 16 has an inside taper 27 at the open end such that, under initial pressure, the membrane 3 may expand in diameter to the extent of the inside wall of that taper thus allowing the front of driven piston 10, comprising the flexible lip 11, to push the membrane within itself and therefore "outside in" and creating the membrane wall portions 3A and 3B, the inner surfaces thereof sliding relative to each other. While the package is progressively emptied, the membrane 3 is peeled off the cartridge wall 16A behind the driven piston and trails the driven piston 10. During the dispensing process, the cartridge outlet 17 acts as a support against the forward thrust of the whole package assembly 1 within the cartridge assembly 15. The cartridge supporting device is not shown. In order to ensure the "outside in" function of the membrane and as shown on Fig. 3, it is advantageous to align the driven piston 10 with its flexible lip 11 concentrically relative to the cartridge cylinder inside wall 42A and therefore the package assembly 1. Such an alignment means, in the form of an insert 37 which is set within the stepped and/or tapered end 41 of cartridge cylinder 42, guides and aligns the driven piston 10. The inner diameter 37A of the insert 37 centers the driven piston 10 relative to the cartridge cylinder inside wall 42A and package assembly 1 and restricts the outer diameter of the flexible lip 11 such that during the initial phase of dispensing it will push the end surface of membrane 3, which is in contact with the front side of the piston, ahead so as to enter the cylinder wall supported membrane package and turn the membrane "outside in" within itself. In Fig. 3A the inner diameter 37A and passage dimension of the alignment means insert 37, which need not necessarily be a ring or circular, is equal or smaller than the cartridge cylinder inside wall 42 or package membrane 3. Adjacent to the outlet side end of the insert 37 is a section of the cylinder inside wall 42C which is equal or larger in diameter than the inside diameter of the cylinder wall 42 for initiating the "outside in" function. The outlet end of the insert 37 can have a transition taper 42B as well as the cartridge inner wall at 42C, or only the cartridge inner wall is tapered at 42D, as shown on the right side of cartridge wall 42 in Fig. 3A. Fig. 4 shows a variant to the embodiment described in Fig. 2B, whereby a package assembly 1 is contained within a cartridge assembly 21 having a cylinder 22 with inner wall 22A and taper 28, and a cartridge outlet 23, receiving the outlet 5 of outlet adaptor 4. The driven piston 10 with vacuum relief passage 71 and lip 11 is driven by a drive rod 20 driving a compacting plunger 24 with vacuum passage 75 having a smaller front diameter and a larger disc like rear portion 25 compacting wall portions 3A and 3B of membrane 3 within the annular space 26 as it trails behind the driven piston 10. The same vacuum relief passages 71 and 75 are as shown in Fig. 3. Fig. 5A shows a package assembly 29 containing liquid chemical 2, similar to that as previously described in Fig. 1, with the same outlet adaptor 4, outlet 5 with sealing lips 6 and 7 and crimped ring 8, but without the driven piston 10 attached to laminate foil package. Fig. 5B shows the package assembly 29 of Fig. 5A within a cartridge assembly 30 just prior to dispensing but, unlike Figs. 2A, 2B, 3 and 4, the drive piston 31 with vacuum relief passage 76 is directly connected to the drive rod 20 and functions as does the driven piston 10 with lip 11 in Figs. 2A, 2B and 3 by virtue of having a lip 32. The drive piston 31 is axially aligned relative to the package assembly 29 within the cartridge assembly 30 via drive rod 20 and a support frame 33. The drive piston 31 comprises, at its center, a cavity 38 for receiving the end closed by crimped ring 12 of the package assembly 29. The cartridge assembly 30 is similar to the cartridge assembly 21 of Fig. 4 with the difference that the piston side end of the cylinder 22 has an enlarged diameter section 34 with a transition taper in between having the same effect as taper 27 or 28 of the previous embodiments for allowing the expansion of membrane 3 to that greater diameter, therefore allowing the piston to push the membrane package within itself and "outside in". Similar to the driven piston 10, drive piston 31 with vacuum relief passage 76 and lip 32 has an inner contour 35. The outlet adaptor 4, as shown in Figures 1 to 5, has on its membrane-side a male contour 36 to fit closely against the female contour counterpart 19 or 35 of the driven piston 10 as well as that of the drive piston 31, Fig. 5B, so as to ensure the complete discharging of the material 2 from the package assembly. The male contour 36 requires that the outer diameter of the outlet adaptor 4 is larger than the inside diameter of the cylinder wall 16A such that the outlet adaptor 4 is retained and centered between the wall of cylinder 16 and the cartridge outlet 17. Figures 1 to 5 show outlet adaptor 4, with lips 6 and 7, which retains and seals the package between the outlet adaptor 4 and the re-usable cartridge outlet 17, 23 and centers the outlet adaptor 4 relative to the cartridge cylinder 16, 22, 30 and the cartridge outlet 17 as well as providing a male contour 36 to match the female contours 19, 35 on the driven pistons 10, resp. on the drive piston 31.

Claims: A cartridge assembly for dispensing at least one component, comprising a cartridge (15, 21) having a rigid cartridge cylinder (16, 22, 42), a membrane (3) being a container having a closed end (12) and an outlet end (8) and a dispensing assembly (10, 31, 72), the cartridge assembly being configured thus, that the membrane (3) is turned "outside in" within itself by the action of the dispensing assembly such that the inner surfaces of the turned "outside in" and the wall portions (3A, 3B) of the membrane slide relative to each other during emptying of the package, characterised in that the dispensing assembly is provided with sealing means (11, 32) acting on the folded walls (A, 3B) of the container containing liquid chemical (2) for sealing the gaps between the walls (3A, 3B) of the membrane (3) and the outlet being provided with an outlet adaptor (4) having at least one sealing means (6, 7) on the outer diameter of its outlet (5). A cartridge assembly according to claim 1, characterised in that the sealing means is a sealing lip (11, 32) at the piston (10, 31, 72) acting on the folded walls of the membrane. A cartridge assembly according to claim 1 or 2, characterised in that the piston side end (41) of the cartridge cylinder (42) is provided with a means (37) for centering the piston (10), relative to the inner wall (42A) of the cartridge cylinder or package membrane (3) respectively, whereby the passage dimension or diameter (37A) of the centering means (37) is equal to or smaller than the diameter of the inner wall (42A) of the cartridge cylinder and/or the innermost membrane wall of the turned "outside in" container (3). A cartridge assembly according to claim 1 or 2, characterised in that the cartridge cylinder inside wall has a piston side end section (27, 28; 34) which is larger than the remaining part of the cartridge cylinder inside wall (16A, 22A). A cartridge assembly according to claim 4, characterised in that the end section (27, 28) is tapered. A cartridge assembly according to claim 4, characterised in that the end section (34) has a step with a transition taper in between. A cartridge assembly according to claim 1, characterised in that the cartridge cylinder inside wall has a piston side end section (41) which inner diameter is larger than the remaining part of the cartridge cylinder inside wall (16A, 22A), the first part from the end receiving the centering means (37), this end section including the centering means being formed with at least one transition taper (42B, 42C, 42D) in between. A cartridge assembly according to any of claims 1 to 7, characterised in that the piston (10, 31, 72) and the drive plunger (18, 24) of the piston assembly have each a vacuum relief passage (71, 75, 76). A cartridge assembly according to claim 1, characterised in that the sealing means at the outlet adaptor consists of at least one pressure actuated sealing lip (6, 7). A cartridge assembly according to any of claims 1 to 9, characterised in that the cartridge assembly comprises a cartridge outlet (17, 23) receiving the outlet (5) of the outlet adaptor (4, 58) of the package assembly (1, 29). A cartridge assembly according to any of claims 1 to 10 for dispensing more than one component, characterised in that the cartridge assembly (15) comprises a common cartridge outlet (17) for the package assemblies (1) contained in the cartridge assembly. A cartridge assembly according to claim 10 or 11, characterised in that the bore of the cartridge outlet (17, 23) receiving the sealing means (6, 7) at the outlet (5) of the outlet adaptor (4) is tapered (39). A cartridge assembly according to claim 1, characterised in that the piston (10) is attached to the package assembly (1) and driven by a drive plunger (18, 24) with a drive rod (20), whereby the drive plunger (24) has a smaller front diameter and a larger disc like rear portion (25) for compacting the turned "outside in" membrane wall portions (3A, 3B). A cartridge assembly according to claim 1, characterised in that the piston (31) provided with a sealing lip (32) is independent of the package assembly (29) attached to and driven by the drive rod (20). A cartridge assembly according to claim 1, characterised in that the package content side contour (19, 35) of the piston (10, 31) with the lip (11, 32) matches the package content side contour (36) of the outlet adaptor (4).

Inventors: KELLER WILHELM A, KELLER, WILHELM A.
Applicants: MIXPAC SYSTEMS AG
Application year: 1997
Main classification: B65D83
IPC codes: B05C17, B65D83, B65D81, B05C11