Dispensing apparatus for pasty substances

Abstract: Manually operated dispensing apparatus for pasty substances, in particular silicone, comprising a hollow vessel (2) provided with a rear loading opening through which the paste to be dispensed is introduced, a front paste dispensing spout (26), a manually operated dispensing actuation lever (3), a plunger element (7) displaceably located inside said hollow vessel, which is arranged to be closed on its rear side by a sealing element (6), said dispensing actuation lever (3) being formed by two segments (3a, 3b) arranged at an angle with respect to each other. An elastically deformable air chamber (4) is pressed by the actuation of said lever (3) so as to cause its volume to be reduced and the air contained in said air chamber to be injected under pressure, through an aperture (20) in the wall of the sealing element (6) and a double check valve (5), into the cavity formed between the rear sealing element (6) and the plunger element (7). The air chamber is an elastically deformable concave air chamber with a substantially circular shape, and is applied in a tightly sealed way on to the outer surface (10) of said sealing element.

Description: This invention relates to an improved apparatus for dispensing pasty substances, such as in particular silicone, which are contained in tube-like flexible sealed vessels. It is commonly appreciated that dispensing pasty substances both in industrial applications and at home is a duty that needs complying with a number of prerequisites, ie. easy and convenient manoeuvrability by a single operator, capability of dispensing the paste as a continuous, uninterrupted extruded strip that shall break off abruptly and neatly as soon as the operator stops dispensing at his/her will, permanent separation of the paste to be dispensed from the air even for prolonged periods of time (so as to avoid interactions of the air with the substance to be dispensed, such as for instance silicone), convenience in handling and re-loading the dispensing apparatus. While these basic requirements shall in general be complied with by each type of manually operated dispensers, this turns out to be of particular importance in the case of those dispensers that have to be used or operated with a single hand and that need to be particularly simple and low-cost in their construction to allow for an application on an industrial scale. The solution which is most widely used currently consists of dispensing devices that are substantially conceived as variations of manually operated dispensing guns in which a sealed cartridge containing the substance to be dispensed is inserted; the sealed cartridge terminates at its front dispensing end with a sealed spout, which is cut open immediately before using the gun, and at its opposite end with a substantially hermetically sealing element acting as a moving cap, which is inserted on the rear side into the outer casing of said cartridge so as to be capable of sliding forward under the thrusting action of a dispensing plunger. Loading said cartridge substantially requires inserting the same cartridge in the gun-type dispensing apparatus so as, upon closing again said apparatus, a plunger is brought to push against the sealing element of the cartridge. To operate such a type of dispensing apparatus, all that is then needed is unsealing the front dispensing spout and operating a lever so that it correspondingly acts on said plunger element which, moving forward due to the actuation of said lever, pushes forward the sealing element to move toward the front dispensing spout so that the paste contained in the cartridge, pushed by the sealing element which is in turn pushed by the plunger element, will ultimately be squeezed out of said spout. When there is no more paste left in the cartridge due to repeated dispensing, the plunger element is extracted again from the body of the dispensing apparatus, while the empty cartridge is then replaced with a new, full cartridge, so that the just described dispensing procedure may be restarted. Such type of dispensing units is widely known, so that no need arises to describe it here any further. This dispensing apparatus performs in a satisfactory way in cases of limited use or when there are no particular handling or manoeuvrability problems to be encountered. Conversely, when it comes to industrial applications, following drawbacks appear to be associated therewith: 1) High costs. As a matter of fact, the cartridge containing the paste to be dispensed is usually made as a rigid plastic moulding and, notwithstanding its altogether high costs, it is inevitably thrown away when emptied. In applications requiring great amounts of paste to be dispensed and, as a consequence, the use of a large number of cartridges, the ultimate expense that must be sustained for such one-way cartridges is certainly quite considerable. 2) Poor convenience in handling. When working in large structures, such as for instance buildings, the operator needs to use tools that are very convenient to handle, compact and operable with a single hand, since it quite often occurs that the other hand is used to keep the workpiece in place or even the same operator in a stable position. Dispensing guns of the traditional type are rather cumbersome and quite often require the use of both hands at the same time. 3) Poor cleanliness. In the case of an intensive use, traditional-type dispensing guns tend to cause the paste to seep through inside the vessel of the apparatus containing the cartridge, thereby clogging it up or, anyway, making it more difficult and time-consuming to replace the cartridge. Furthermore there is known from US-A-3 568 892 a dispensing apparatus comprising an actuating lever and a pressurised gas containing casing. Gas released through an orifice into a chamber moves a plunger forward. It would be desirable, and it is one of the objects of the present invention, to avoid actuation by pressurised gas and to provide a dispensing apparatus for pasty substances which is capable of eliminating the afore cited drawbacks, is reliable in both its operation and handling, can be used in mass-manufacturing applications, and can be produced with practicable techniques. It will however be fully apparent that the dispensing apparatus according to the present invention can actually be advantageously used in all cases where the need arises to dispense in a controlled way a pasty substance stuffed into containers that must be replaced when emptied. The invention has the features and characteristics as recited in the appended claims. However, for a better insight it will be further described by way of non-limiting example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view in a lengthwise direction of the dispensing apparatus according to the present invention, shown in the condition in which the actuation lever is lifted; Figure 2 is the same cross-sectional view in a lengthwise direction shown in Figure 1, whereas the actuation lever is fully lowered at the end of the dispensing phase; Figure 3 is an enlarged view of the zone surrounding the double check valve. Figure 4 is a view of an improved embodiment of the dispensing apparatus according to the present invention; Figure 5 is a view showing a different arrangement of the embodiment shown in Figure 4. Referring now to the above listed Figures, it can be noticed that they show an apparatus 1 for dispensing pasty substances, comprising at least a hollow vessel 2, a dispensing actuation lever 3, an elastically deformable concave air chamber 4 being substantially circular in its shape, a double check valve 5 to let air in and out, a rear sealing element 6 closing said hollow vessel 2 on its rear side, a plunger element 7 sliding inside said hollow vessel 2. The actuation lever 3 is arranged substantially at a right angle at 8, wherein said angle actually divides the lever into its two segments 3a and 3b. The segment 3a is hinged at a point 9 that is situated on an outer rim of the sealing element 6, and it rests, when being pushed, against the elastically deformable air chamber 4 which is permanently and in a tightly sealed way applied with its circular concave portion against the circular periphery of the outer surface 10 of the sealing element 6. The segment 3b is projecting forward in an oblique position, which however is substantially coplanar with respect to the vessel 2. The sealing element 6 is applied to the rear portion of the vessel 2 by means of normal screw threads or similar fastening means. On the inner side of said sealing element 6, in an appropriate receptacle, the valve 5 is provided to control the passage of the air. Said valve may be of a per se known type; in particular, the body of the valve 5 is provided with three bores to ensure the passage of and regulate the air flow, ie.: the bore 19 lets air into the inner cavity 11 of the hollow vessel 2; the bore 14 is pierced through the wall of the sealing element 6, wherein the pin 18 of the valve protrudes from the surface of said element in correspondence of the projection of the segment 3b of the lever 3 on the body of the hollow vessel 2, whereas in the segment 3b, in correspondence of the protruding pin 18 of the valve 5, a relief aperture is provided so that, when said segment 3b is pressed against the body of the vessel 2, the pin 18 is not pressed by the segment 3b; the bore 20 is pierced through the wall of a side portion of the sealing element 6 so that it communicates with the inner side of said elastically deformable air chamber 4. The plunger element 7 is inserted in the hollow vessel 2 so that its side surface 21 comes into contact in a substantially tightly sealing way with the corresponding inner surface of the vessel 2. In the dispensing zone of the hollow vessel 2, the latter is sealed by a surface 24 that has a bore in its central portion. In such a bore there is inserted an element 26, or dispensing spout, which is substantially cylindrical in its shape and is open at both its ends so as to put the inside of the vessel in communication with the outside and the rather sharp edges of the inner side. The dispensing apparatus according to the present invention operates in the following manner: after unsealing the rear portion of the hollow vessel 2, by unscrewing the sealing element 6, and extracting the plunger element 7 therefrom, preferably with the aid of a string connected to the rear portion of said plunger element, a flexible vessel 23, typically in the shape of a pouch and filled with the paste to be dispensed, is inserted in the hollow vessel 2. Then the plunger element 7 is closed in again by pushing it against said flexible vessel 23 until it reaches its stop position as determined by said pouch-like flexible vessel having completely filled up the hollow vessel 2, ie. having being fully inserted to reach the opposite side of the vessel 2 as compared to the insertion one. Then the sealing element 6 is put on again by screwing it on the rear portion of the vessel 2. Thereupon, the dispensing apparatus is ready for use. At this point, all it takes to operate the dispensing apparatus is seizing the vessel 2 and, while holding it with one hand, repeatedly pressing down the lifted segment 3b against the body of the same vessel. Upon each pressure exerted in this way on the lever, the segment 3a thereof is caused to press against the elastically deformable air chamber 4 which, following the reduction in its volume, ejects the air contained therein through the bore 20 and, thereafter, through the bore 19 provided in the valve 5, so as to send it into the inner cavity 11 of the hollow vessel 2 and, namely, the cavity formed between the inner surface of the sealing element 6 and the plunger element 7. At the end of its downstroke, the lever 3 returns automatically to its lifted, ie. initial or starting position owing the the spring-back action of the material which the elastically deformable air chamber 4 is made of; during this automatic return movement of the lever, the interior of the elastically deformable air chamber 4 fills up again with new air that is taken in from the outside through the bore 14 and the bore 20 as described and defined afore. Upon returning of the lever to its initial, lifted position, the segment 3b shall be pressed down again if the just described operation cycle of the dispenser is to be repeated. As the amount of air caused to flow into the above defined inner cavity of the vessel 2 increases, there will be an increase also in the pressure tending to push forward the plunger element 7, thereby achieving first the result of causing the flexible vessel to get pierced against the inner edge 27 of the dispensing spout 26 and then the result of causing the paste to be dispensed, contained in said flexible vessel 23, to be squeezed out of said newly pierced aperture into the spout 26 and, from here, to the outside. When the paste in the flexible vessel is fully dispensed and the same vessel is therefore empty, the plunger element 7 will stop and this will cause the lever 3 to substantially become stiff and get jammed. Alerted by this fact, the operator will at first remove the overpressure existing inside the vessel 2 by simply pressing down the pin 18 with a push-button or similar means. This will be effective in causing the interior of the vessel 2, under pressure, to be put in direct communication with the outside, through the bores 14 and 19 of the valve 5, thereby bringing about an almost immediate pressure equalization. Once this has been accomplished, the sealing element 6 will be capable of being removed quite easily, so that the plunger element 7 can be extracted from the vessel 2, preferably with the aid of a string or similar means attached to a fastening element thereof, such as for instance a grommet 30 provided on the outer surface of said plunger element 7. Through such a removal of the plunger element 7, the flexible vessel 23 becomes released, so that it can be easily extracted from the vessel 2, too. For better convenience and swiftness, the inner surface of the plunger element 7 may be such as to be provided with some fungiform protrusions free from sharp edges. Such protrusions, owing to the pressure between the plunger element 7 and the flexible vessel 32, will get stuck to said flexible vessel, albeit without piercing or tearing it open, so that the plunger element 7, when extracted from the vessel 2, will automatically pull out also the flexible vessel 23, which is firmly held by the undercuts of said protrusions 31. While this dispensing apparatus operates in an altogether satisfactory way, it still may have some drawbacks: in the first place, the construction of a cylindrical hollow vessel can give rise to manufacturability problems which, although solvable with currently available techniques, would in any case bring about higher fabrication, tooling and mould costs; in the second place, the protrusions that get inserted into the flexible vessel filled with pasty substance, and which serve to extract said flexible vessel when emptied, can easily tear or break it, with the result of letting part of the substance still in the flexible vessel escape therethrough, while this leaking substance, by spreading all around and drying up, would surely clog the inner cavity of the hollow vessel, thereby interfering with the insertion of a new flexible vessel filled with pasty substance, the subsequent capping or sealing of the same hollow vessel and the free manoeuvrability of the actuating lever for dispensing the paste. In view of eliminating also these drawbacks, following improved embodiment of the apparatus according to the present invention is proposed, whereby referring in particular to the Figures 4 and 5, it can be noticed that, instead of being loaded and unloaded from the rear through the provision of a corresponding sealing element of the afore described type, the dispensing apparatus according to this improved embodiment of the present invention is provided with a front sealing element 15 which is capable of being removed from the body of the hollow vessel, and which can be applied thereto by attaching it using anyone of a variety of appropriate methods, such as for instance by means of screw-on threads 16, snap-fitting, etc. All it takes to introduce the flexible vessel full of pasty substance to be dispensed is just removing said front sealing element, taking out the empty flexible vessel that had been previously inserted in the hollow vessel of the dispensing apparatus, introducing the new flexible vessel with the pasty substance by pushing the plunger element (7) backwards, and capping again the vessel with said front sealing element. Even in this case the inner edge 27 of the dispensing spout 26 will perforate the flexible vessel full of pasty substance under the thrusting action exerted by the plunger element 7, so that the dispensing apparatus is ready for use and the paste can be pressed outside. All it takes now to operate the dispensing apparatus is just doing exactly what has been described in this connection for the afore illustrated embodiment. A further advantage of this improved embodiment according to the present invention derives from the fact that it allows for the elimination of the protrusions for attaching the flexible vessel to the surface of the plunger element 7, thereby simplifying the construction even further. By doing away with said protrusions, the risk of the flexible vessel to get torn or broken, with a resulting leakage of paste and clogging of the apparatus, is practically eliminated. It will of course be apparent that each dispensing apparatus 1 can be the subject of any embodiment differing from the afore illustrated ones, or of any such modification as considered to be appropriate, without departing from the scope of the present invention. As a matter of fact, the peculiar features, characteristics and advantages of the apparatus according to the present invention are clearly recognizable: simple and cost-effective construction; convenient handling and manoeuvrability in practical use, since the apparatus can be held and used with a single hand, allowing the operator to work with the body held in positions that may also be quite critical or difficult; overall economy, since it does not require the use of a rather expensive rigid one-way cartridge each time that it must be refilled with paste; and overall cleanliness, since the apparatus is not soiled by paste leakages, even after prolonged use.

Claims: Manually operated dispensing apparatus for pasty substances, in particular silicone, comprising at least a hollow vessel (2) provided with at least a rear loading opening through which the paste to be dispensed is introduced, a front paste dispensing spout (26) , a manually operated dispensing actuation lever (3), a plunger element (7) displaceably located inside said hollow vessel, which is arranged to be closed on its rear side by a sealing element (6), characterized in that the dispensing actuation lever (3) is formed by two segments (3a, 3b) arranged at an angle with respect to each other; an elastically deformable air chamber (4) is pressed by the actuation of said lever (3) so as to cause its volume to be reduced and the air contained in said air chamber to be injected under pressure into the cavity (11) formed between the rear sealing element (6) and the plunger element (7) through an aperture (20) in the wall of said sealing element (6) connecting the interior of said air chamber (4) with a double check valve (5). Dispensing apparatus according to claim 1, characterized in that the segment (3a) of the lever (3) has its fulcrum in correspondence of a position (9) on the outer edge of said rear sealing element (6), and in that the segment (3b) is bent at a substantially right angle with respect to said first segment, in a coplanar direction with respect to said first segment and the axis of the vessel (2). Dispensing apparatus according to claim 1 or 2, characterized in that said air chamber is an elastically deformable concave air chamber (4) being substantially circular in its shape, and is applied in a tightly sealed way on to the outer surface (10) of said sealing element (6). Dispensing apparatus according to any of the preceding claims, characterized in that said valve (5) is formed by a hollow valve body and is provided with two aligned, coaxial, elastically connnected shutters and three apertures (14, 19, 20). Dispensing apparatus according to any of the preceding claims, characterized in that a push-button (32) is provided on the segment (3b) of the lever (3), said push-button being intended to act on the pin (18) so as to cause the air in the cavity (11) to be vented outside. Dispensing apparatus according to any of the preceding claims, characterized in that said plunger element (7) is provided on its rear portion with extraction means, preferably a string connected to a fastening element (30). Dispensing apparatus according to any of the preceding claims, characterized in that the inner surface of the plunger element (7) is provided with some protrusions (31), preferably in a fungiform shape. Dispensing apparatus according to any of the preceding claims from 1 to 6, characterized in that said hollow vessel (2) is provided with a removable front sealing element (15) to which said front dispensing spout (26) is attached. Dispensing apparatus according to claim 8, characterized in that said removable front sealing element (15) is attached to said hollow vessel by means of screw-on threads (16).

Inventors: SANDRIN GIANNI, SANDRIN, GIANNI
Applicants: RO SA PLAST SPA, RO-SA PLAST S.P.A.
Application year: 1993
Main classification: B05C17
IPC codes: B05C17