EP0276665A2 - Pressure-activated dispenser for operaing twin cartridges - Google Patents

Abstract

The conventional dispenser, designed in "pistol form", for twin cartridges (40) with a feed piston (42) has a pressure-activated cylinder/piston unit (1) with plungers (7) extending from the piston (5, 6) and intended for the advance of the feed piston. The problem is that, during the piston advance, the reaction forces acting on the two plungers (7) from the feed pistons (42) can differ greatly (different viscosities of the substances contained in the two cartridge cylinders 41 and/or different cross-sections of the cartridge cylinders 41). To prevent the piston (5, 6) from "tilting" or jamming, according to the invention there is in the cylinder space (14, 15) a rigid longitudinal guide (10) between the two cylinder bottoms (2, 4), on which the piston is supported slidably by means of an elongate guide bore (9). The longitudinal guide (10) can at the same time stiffen the cylinder (2, 3, 4) and, furthermore, guide the pressure medium into the pressure space (15) behind the piston (5, 6) via a longitudinal channel (20). In connection with this, a rapid venting (21 - 24) for the pressure space (15) and control means (31, 32) for the return of the piston unit (5, 6) together with plungers (7) to the initial position are described. Moreover, restoring means (38, 39) for the piston to relieve the plungers after each advance step and indicator members (60, 61) for the cartridge filling level are disclosed. <IMAGE>

Description

The invention relates to a discharge device for operating double cartridges provided with delivery pistons, with a pressure medium-operated cylinder / piston unit, in the region of the cylinder base arranged holding means for exchangeable reception of the cartridges, and from the piston outgoing, through the cylinder bottom mentioned rams for the propulsion of the delivery pistons.

The double cartridges intended for operation by the discharge device are used in a known manner for processing so-called two-component masses, the two components of which are stored in separate, cylindrical containers and are discharged through the cartridge mouth when acting on the delivery pistons. Here, the components are usually brought together in a flow mixer adjoining the cartridge mouth and mixed intimately. In dispensing devices of the above-mentioned type with a (usually pneumatically operated) cylinder / piston unit, when operating double cartridges there is the particular problem that the piston tends to tilt or "tilt" during the pressurization in the cylinder, because the reaction forces acting on the piston two adjacent tappets can be very different. Such differences are mainly due to different viscosities or outflow resistances of the two components to be discharged and / or in different cross sections of the the cartridge container and delivery plunger in accordance with a mixture ratio different from that required for the two-component system in question. Such inevitable tilting moments on the device piston naturally lead to jamming or inadequate sealing of the piston or to other malfunctions.

It has so far not seemed easy to solve these difficulties: either the two plungers and, above all, their connection to the piston would have to be designed to be particularly rigid, or an excessively long piston guide on the cylinder, combined with a cylinder wall which was resistant to local "bulging", would have to be provided. However, both measures would - if at all effective - cause a considerable additional weight of the dispensing device and thus make the manually operated device, which is usually designed in the form of a pistol, unwieldy.

The object of the invention is to design a discharge device of the type mentioned so that even very different reaction forces on the part of the two plungers during the piston advance do not have a disadvantageous effect on the function and handling of the device.

According to the invention, this object is achieved in that the cylinder space contains a rigid longitudinal guide connecting both cylinder bottoms and penetrating the piston, on which the piston is slidably supported by means of a guide bore extending in the longitudinal direction.

Such an arrangement ensures reliable piston guidance and sealing in a simple manner and with little effort, even with a strongly asymmetrical piston load. The longitudinal guide built into the cylinder - in the case of normally dimensioned plungers and other parts of the piston / cylinder unit - only increases the overall weight and the unit dimensions insignificantly, but can also increase the stability of the entire piston / cylinder unit.

Appropriate constructive designs in connection with the longitudinal guide according to the invention are specified in claims 2 to 4. However, the longitudinal guidance can perform other functions in addition to the straight guidance of the piston, on the one hand in the supply of pressure medium for the piston propulsion (claims 5 to 8) and on the other hand for guiding a return element, which allows the piston to retreat somewhat after a forward stroke of the piston (claims 9 to 10). Finally, claims 11 to 15 relate, as further expedient measures on the dispensing device, to an indication of the cartridge filling level during the dispensing.

• Fig. 1 einen (teilweise weggebrochenen) schematischen Längs­schnitt durch ein Austraggerät gemäss einer ersten Ausführungsform, wobei eine eingesetzte, vom Gerät zu bedienende Doppelkartusche strichpunktiert angedeu­tet ist, und
• Fig. 2 und Fig. 3 als Varianten zu Fig. 1 je einen hälfti­gen Schnitt durch die Kolbenpartie gemäss anderen Ausführungen.

Exemplary embodiments of the discharge device according to the invention are explained in detail in connection with the drawing. Show it:

• 1 shows a (partially broken away) schematic longitudinal section through a discharge device according to a first embodiment, an inserted double cartridge to be operated by the device being indicated by dash-dotted lines, and
• Fig. 2 and Fig. 3 as variants to Fig. 1 each a half-section through the piston section according to other versions.

In the pneumatically operated discharge device according to FIG. 1, the cylinder / piston unit is denoted overall by 1. For convenient handling, the device is “pistol-shaped” with a handle 30 which, for example, is molded onto a cylinder base 2 or is in any case firmly connected to it. Adjoining the cylinder base 2 (on the left in FIG. 1) there is a replaceable double cartridge 40 to be operated by the device (shown in dash-dot lines), with holding means for receiving the cartridge, for example in the form of receiving grooves 49 for a cartridge flange 43, also on Cylinder base 2 can be molded. The double cartridge has two cylindrical ones Reservoir 41 on, each with a delivery piston 42. When the delivery piston is moved to the left, the cartridge contents - the two components of a two-component system - are discharged from the cartridge; This discharge is usually carried out step by step in several "batches" with waiting times in between. For the corresponding propulsion of the two delivery pistons, the discharge device has two plungers 7 which start from the device piston and pass through the cylinder base 2. 1 shows the situation when the cartridge is still approximately full, that is to say after the plungers have only covered a small part of the entire stroke.

The pneumatic cylinder of the cylinder / piston unit 1 is composed of the already mentioned cylinder base 2, the opposite cylinder base 4 and the cylinder wall 3. The piston which is displaceable in the cylinder essentially consists of the piston plate 5 and a hub 6 which is firmly connected to it and in which the two plungers 7 are inserted. What is essential in the present discharge device is a rigid longitudinal guide 10 present in the cylinder space, which preferably connects the two cylinder bases 2 and 4 coaxially to the cylinder axis and penetrates the piston 5, 6. The piston is slidably supported on this longitudinal guide, which is designed here as a round rod, by means of a guide bore 9 which extends in the longitudinal direction (in the present case divided into two sections). An annular seal 16 inserted in the piston plate 5 seals the guide bore 9 from the longitudinal guide 10. The longitudinal guide 10 is screwed to the cylinder base 2 on the one hand. The other end of the longitudinal guide protrudes through a through hole 13 in the cylinder base 4, which is held by means of a cap nut 11 tightened on the longitudinal guide 10 and rests axially on the cylinder wall 3 with an annular surface 12 on the circumference. The other end of the cylinder wall 3 is received by a recess 18 in the cylinder base 2; of course it could be axially supported analogously to the cylinder base 4 or also firmly with the cylinder base be connected to the 2. By tensioning the longitudinal guide 10 between the two cylinder bases under tension by the nut 11, it gives the cylinder a high degree of stability. Above all, however, it reliably prevents the pistons 5, 6 from tilting during the advance, even with very different reaction forces which act on the pistons from the side of the two plungers 7. This not only ensures trouble-free piston guidance and piston sealing, but also an absolutely "synchronous" propulsion of the two delivery pistons 42 and thus a constant volumetric ratio of the two components when they are discharged from the cartridge cylinders 41. With regard to good piston guidance, it is recommended that guided length l (length of the guide bore 9) to be measured approximately in the range of 0.6 to 1.4 times the ram distance a.

It should be mentioned here that the two plungers 7 - and thus the two cartridge containers 41 - do not necessarily have to lie vertically one above the other (as shown in the drawing plane in FIG. 1) with their longitudinal axes, but also depending on the position of the double cartridges in the Discharge device, for example, can be arranged horizontally next to one another. 1, the longitudinal guide 10 in the central axis of the cylinder wall 3 and the two plungers are arranged symmetrically on both sides thereof, deviating, that is, asymmetrical arrangements are also possible, especially if unequal reaction forces are to be expected from the plungers from the outset , especially if the cross sections of the two cartridge containers are unequal. Finally, "double cartridges" are understood to mean both cartridges made in one piece with two containers and those with containers of two-component systems which are manufactured separately or are to be inserted into the device.

In addition to the function already described of supporting the piston and guiding it straight along its entire stroke length, the longitudinal guide can perform 10 other tasks in connection with the discharge device: it has a longitudinal channel 20 in order to guide the pressure medium into the cylinder space 15 on the side of the piston facing away from the plungers 7. The compressed gas for the piston feed is fed through a line 33 in the handle 30 of the device and metered by a control valve 34 to be operated by means of a hand lever 35. From the valve 34, the compressed gas passes through a line 26 arranged in the cylinder base 2 into the longitudinal bore 20 and in this behind the pistons 5, 6, where one or more radial bores 21 establish the connection to the cylinder space 15. In the area of this transition there is an expanded section of the bore 20, a quick exhaust valve controlled by the pressure medium, for example a shuttle valve, consisting of the piston 23 and the valve spring 24. When the control valve 34 is actuated, the compressed gas in the longitudinal channel 20 displaces the valve piston 23 against the spring 24 so far to the right (in FIG. 1) that it can enter the cylinder space 15 via the bore 21 and advance the device piston 5, 6. Immediately after closing the control valve 34 - a so-called 2/3-way valve, which at the same time ensures the venting of the line 26 and the bore 20 - the valve piston 23 is returned by the spring 24 to the rest position shown, whereby it is a previously blocked Vent opening 22 for the cylinder space 15 releases. Thus, the piston plate 5 is relieved of pressure each time the control valve 34 is not actuated (bore 20 depressurized).

Preferably, a changeover valve with a multiple control piston 31 and valve spring 32 is also provided, which is connected between the outlet of the control valve 34 and the cylinder chamber 14, which is located on the tappet side of the device piston 5, 6. The control piston 31 can, if necessary, be operated simultaneously with the hand lever 35, for example with the thumb of the hand holding the carrying handle 30. In the illustrated rest position of the changeover valve, the piston 31 releases the pressure medium line 26 on the one hand and a ventilation line 28 on the other hand, via which the air can escape from the cylinder space 14 during the advance of the device piston 5, 6. The switching valve 31, 32 serves to return the device pistons 5, 6 with the plungers 7 to the starting position (on the right in FIG. 1) in order to prepare for a replacement of the cartridges 40. If the switching piston 31 is moved to the left against the spring 32, the pressure medium line 26 and the vent line 28 are blocked, while a previously blocked pressure medium channel 27 leading from the outlet of the valve 34 to the cylinder chamber 14 is opened. Accordingly, if the control valve 34 and the changeover valve 31, 32 are actuated at the same time, the cylinder space 14 is pressurized with gas and the device piston 5, 6 is shifted to the right, the valve piston 23 remaining in the rest position and the ventilation of the cylinder space 15 via the bores 21 and the opening 22 takes place. It is of course also possible to connect the channel 27 directly to the pressure medium line 33 instead of branching off the line 26; it is then only necessary to actuate the valve 31, 32 for the return of the piston 5,6.

The above-mentioned quick ventilation of the space 15 and thus the pressure relief of the piston plate 5 is of importance insofar as it may be desirable to interrupt the action of the delivery pistons 42 in the cartridge 40 by the plunger 7 clearly after each piston and plunger advance The delivery piston 42 after the partial discharge of the cartridge contents has contributed to the fact that an undesired subsequent flow does not occur at the end of a discharge step (closing of the control valve 34). By means of an additional measure in the area of the device piston 5, 6, whereby the longitudinal guide 10 can also be used, it is achieved that the tappets 7 are lifted from the delivery piston 42 by a small amount each time the pressure in the cylinder space 15 is released: for this purpose there are in a recess 37 housed inside the piston hub 6, an annular return member 38 and one or more return springs 39. The return element 38 can be moved in a frictionally locking manner along the longitudinal guide 10. The return springs 39 are supported between the return member 38 and the piston plate 5, and between the return member and the A limited axial relative movement is possible for the piston. Each time the piston feed begins (pressurizing the space 15), the compression springs 39 are tensioned first, and then when the piston has moved somewhat axially relative to the return element and the spring force overcomes the friction of the return element on the longitudinal guide 10, the return element becomes inside the hub 6 taken away. At the end of the feed and after venting of the space 15, the return element 38 remains on the longitudinal guide 10, while the springs 39 relax and move the piston back against the feed direction by the previously traveled spring travel; it is assumed that the frictional force of the return member on the longitudinal guide 10 is greater than the overall frictional forces acting on the pistons 5, 6. By, as shown, the return arrangement 38, 39 being arranged axially between longitudinal sections of the guide bore 9, the axial length of the device piston 5, 6 is expediently utilized.

A variant of the return arrangement described is shown in FIG. 2, parts which correspond to one another being identified by the same reference numbers. In this variant, the cylinder inner surface 17 is used instead of the longitudinal guide 10 as a friction surface for the likewise annular, but correspondingly larger return member 38ʹ. Return springs 39ʹ are in turn clamped between the return member 38ʹ and the piston 5ʹ, a stop 36 ensuring the precise limitation of the possible axial movement between the parts 38ʹ and 5ʹ. On the other side of the springs 39ʹ there is a driver 8 connected to the piston hub 6ʹ for the return arrangement, which driver 8 is effective in returning the piston to the starting position. As can be seen, the piston plate 5ʹ and the hub 6ʹ can be in one piece and the guide bore 9 can be load-bearing over its entire length. 2 is the same as in the arrangement according to FIG. 1.

When operating the discharge device, neither is the respective Position of the device piston 5, 6 with the plungers 7 and the corresponding position of the delivery piston 42 within the cartridge 40 visible from the outside. The present device is therefore provided with an expedient display element, which is shown, for example, in FIG. 1 and which can easily recognize the cartridge fill level at any time during the discharge. The display element has a push rod 61, which is here directly connected to the piston plate 5 and which penetrates the cylinder bottoms 2 on the cartridge side and carries a pointer 60 outside the same. This slides in a guideway 62 which adjoins the cylinder base 2 and can be provided, for example, with a fill level scale. The guideway 62 is provided here in a strut 47 of the dispenser connected to the cylinder base 2, however, if the strut is omitted, the guideway and / or scale can also be provided directly on the cartridges 40.

Because of the return movement of the piston and the plunger caused by the return arrangement 38, 39 or 38ʹ, 39ʹ after each feed step described above, it can be useful to achieve an even more accurate display of the cartridge fill level, the display element with the return element instead of with to connect the device piston directly. This is illustrated by the example of FIG. 2 by the push rod 61ʹ. An embodiment which is analogous in terms of mode of operation in the case of a return element 38 sliding along the longitudinal guide 10 according to FIG. 1 can be seen from FIG. There, the push rod 61ʹ is angled within the cylinder and connected to the return element 38, a radial bore 59 in the hub 6 ensuring sufficient freedom of movement in the axial direction. The relative movement between the piston unit 5, 6 and the return element 38 can be limited exactly according to FIG. 3 by stops 36ʹ.

A display element that can be moved through one of the cylinder bottoms depending on the movement of the device piston - as described above - could also be used for dispensing devices with only one plunger (for single carto be used with advantage.

Finally, it should be mentioned that all measures according to the invention can of course also be applied analogously to dispensing devices with more than two rams, ie for triple or multiple dispensing cartridges, provided such systems should be introduced.

Claims (15)

Discharge device for operating double cartridges provided with delivery pistons, with a pressure medium-operated cylinder / piston unit, holding means arranged in the area of the cylinder base for exchangeable reception of the cartridges, as well as tappets extending from the piston and guided through the cylinder bottom for the advance of the delivery pistons, characterized in that that the cylinder space (14, 15) is a two cylinder bottoms (2, 4) connecting and the piston (5, 6) penetrating rigid longitudinal guide (10), on which the piston (5, 6) extending in the longitudinal direction by means of a Guide bore (9) is slidably supported. 2. Dispensing device according to claim 1, characterized in that the guide bore (9) is provided with an annular seal (16) with respect to the longitudinal guide (10) designed as a round bar or tube. 3. Discharge device according to claim 1 or 2, characterized in that the guided length (l) of the piston (5, 6) is 0.6 to 1.4 times the distance (a) between the plungers (7). 4. Dispensing device according to one of the preceding claims, characterized in that the longitudinal guide (10) is tensioned between two cylinder bases (2, 4) and at least one of these bases has an annular surface (12) for axia len support on the cylinder wall (3). 5. Discharge device according to one of the preceding claims, characterized in that the longitudinal guide (10) has a longitudinal channel (20) for the pressure medium supply in the cylinder space (15) on the piston side facing away from the rams. 6. Discharge device according to claim 5, characterized in that a pressure medium-controlled quick exhaust valve (23, 24) is present at the transition from the longitudinal channel (20) into said cylinder chamber (15), the piston (23) of which is a depressurized longitudinal channel (20) Vent hole (22) for the cylinder space (15) releases. 7. Discharge device according to claim 5, characterized in that the longitudinal channel (20) via a pressure medium line (26) arranged inside the cartridge-side cylinder base (2) is connected to a control valve (34) accommodated in the handle (30) of the device. 8. Discharge device according to claim 5, characterized by a changeover valve (31, 32) connected to the cylinder space (14) on the piston side of the piston, which in a first position releases a ventilation opening (28) extending from said cylinder space (14) and a pressure medium channel (27) to said cylinder chamber, and in a second position blocks the ventilation opening (28) and releases the pressure medium channel (27). 9. Discharge device according to one of the preceding claims, characterized by a on the longitudinal guide (10) or on the cylinder inner surface (17) guided by friction return element (38, 38ʹ), which relative to the piston (5, 5ʹ) limited longitudinally movable and this is supported by at least one return spring (39, 39ʹ) that can be tensioned during piston jacking. 10. Discharge device according to claim 9, characterized in that the return member (38) and the return spring (s) (39) are arranged within a piston hub (6) between longitudinal sections of the guide bore (9). 11. Discharge device for operating cartridges provided with delivery pistons, with a pressure-operated cylinder / piston unit, in the area of the cylinder base arranged holding means for exchangeable reception of the cartridges as well as at least one plunger which extends from the piston and passes through said cylinder base for the delivery piston advance , characterized by a display element (60, 61) for the cartridge filling level which is displaceable as a function of the movement of the piston (5, 6) and is guided out of the cylinder through the one cylinder base (2). 12. Dispensing device according to claim 11, characterized in that the display element has a push rod (61) penetrating the cartridge-side cylinder base (2) and a pointer (60) connected to it, which slides in a guide track (62) adjoining said cylinder base. 13. Dispensing device according to claim 11 or 12, characterized in that the display element (60, 61) with the piston (5, 6) is connected directly. 14. Discharge device according to claim 11 or 12, characterized in that the display member (60, 61) is connected to a piston return member (38, 38ʹ) which is longitudinally movable relative to the piston. 15. Discharge device according to claim 12, characterized in that the guide track (62) is arranged in a strut (47) extending from the cartridge-side cylinder base (2) and connected to it.

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