US20130193168A1

US20130193168A1 - Dispenser

Info

Publication number: US20130193168A1
Application number: US13/754,391
Authority: US
Inventors: Herbert Ginter
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2012-01-31
Filing date: 2013-01-30
Publication date: 2013-08-01
Also published as: EP2623214A3; DE102012201295A1; EP2623214A2; JP2013154344A

Abstract

In the case of a dispenser for packs containing single-component or multi-component compounds, having a receptacle for the pack, having at least one piston rod and having an advancing mechanism for moving the at least one piston rod in the direction of the receptacle, whereby the advancing mechanism has at least one clamping element that can engage with the piston rod and that can be detachably clamped to the at least one piston rod in order to move it, it is provided that the advancing mechanism is movably joined to the receptacle for the pack in such a way that the advancing mechanism with the piston rod can be moved along the advancing axis out of a first position into a second position. This can prevent or minimize afterflow of the compounds.

Description

This claims the benefit of German Patent Application DE 10 2012 201 295.8, filed Jan. 31, 2012 and hereby incorporated by reference herein.
The present invention relates to a dispenser for packs containing single-component or multi-component compounds, having a receptacle for the pack, having at least one piston rod and having an advancing mechanism for moving the at least one piston rod in the direction of the receptacle, whereby the advancing mechanism has at least one clamping element that can engage with the piston rod and that can be detachably clamped to the at least one piston rod in order to move it.

BACKGROUND

Such a dispenser serves to expel dispensable or pasty compounds that are contained in packs, such as mortar or sealing compounds, at an application site. The dispenser allows an exact metering as well as a precise application of the compound in question. Normally, the dispenser has a piston arranged on a piston rod, whereby said piston can act on the pack and force the pasty compound contained in the pack against an outlet opening. The piston rod is driven by an advancing mechanism that can be detachably clamped onto this piston rod. For this purpose, the advancing mechanism has a clamping element that can clamp onto the piston rod. At the end of a dispensing stroke, at least one additional clamping element blocks the at least one push rod and holds it in the end position of the last stroke. As a result, the advancing mechanism, together with the piston rod, forms a unit. In order to retract the piston rod, for instance, when the pack is replaced, a clamping element that is engaged with the piston rod is uncoupled by means of an unlocking mechanism, and the piston rod is manually retracted.
Dispensers of the generic type are described in German patent application DE 42 31 419 A1, in German utility model DE 20 2004 018 368 U1 as well as in the German translation of European patent DE 699 06 694 T2, related to U.S. Pat. No. 6,286,718, all of which are hereby incorporated by reference herein.
Packs with several chambers which contain the components of a multi-component, flowable, pasty compound, such as mortar and sealing compounds, and in which the chambers consist essentially of cartridges or film tubes, are already known. The term “packs” encompasses, for instance, cartridges having one or more compartments for one or more components of the single-component or multi-component compound that is to be applied and that is either contained directly in the compartments of the cartridge or else that is packaged, for example, in film pouches. The term “packs” also encompasses film pouches that are filled with one or more components of the single-component or multi-component compound to be applied and that are inserted into a receptacle that is separate or that is arranged on the dispenser such as a cartridge holder (also called a cassette). In the case of multi-component compounds, the cartridge holder has separate chambers, corresponding to the number of components and thus to the number of film pouches or cartridges. The most common application is the “side-by-side” application, in which the components of the multi-component compound are packaged in packs that comprise film pouches or cartridges arranged next to each other, whereby, for instance, in the case of two-component compounds, two film pouches or cartridges are provided.
For manufacturing-related reasons, especially pasty compounds contain a certain gas fraction that render the compounds compressible. This compressibility as well as the compressibility/elasticity of the entire system consisting of the compounds, the pack and the dispenser account for a dynamic behavior on the part of the entire system.
When it comes to dispensers of the generic type, the dispensing procedure is carried out intermittently, that is to say, one stroke at a time. At the beginning of the dispensing procedure, in other words, at the beginning of the dispensing stroke, since the compounds in the cartridge chambers or the film pouch are compressible, they are first compressed until the pressure in the cartridge chambers or in the film pouches is so high that the compounds start to flow out. Once this point has been reached and if the dispensing movement continues, the compounds flow out of the cartridge chambers or out of the film pouches at the envisaged mixing ratio and are then fed to a mixing element such as a static mixer. At the end of the dispensing stroke, the system is relieved until the pressure in the cartridge chambers or in the film pouches has dropped to such an extent that the compounds no longer flow out (hereinafter referred to as the relaxation phase). During this relaxation phase, it can be observed that the compounds continue to flow, even though no more stroke movement occurs; this is called “afterflow”.
Particularly in the case of injection mortars, multi-component systems such as, for instance, two-component mortar compounds that have to be mixed at a specific mixing ratio in order to cure properly, have become well-established. Since the two components of a two-component system usually exhibit different compressibility/elasticity behavior, during the afterflow, mortar enters the inlet of the static mixer at a mixing ratio that sometimes diverges markedly from the envisaged ratio. This mixing ratio, which results automatically during the afterflow phase, depends on the compressibility/elasticity characteristics of the two mortar components in the system, whereby the compressibility of the compounds, the elasticity of the cartridge or pack parts, the volume of the mortar compound and the like all play a role. Under unfavorable conditions, the detrimental effect of afterflow can be so pronounced that the mortar coming out of the mixer no longer displays a mixing ratio that is acceptable for the system, as a result of which the mortar compound cannot cure properly.

SUMMARY OF THE INVENTION

A drawback of the prior-art dispensers having a clamping-element drive is that, at the end of a dispensing stroke and thus at the end of the dispensing procedure, the piston rod is secured in the final position of the last stroke. As a result, the relief of force or pressure in the entire system can only take place in one direction, namely, through afterflow of the mortar components into the mixing element.
Mechanical dispensers with a clamping-element drive have a manual force relief mechanism for when the pack needs to be replaced. However, if such a relief mechanism is activated immediately after the last dispensing stroke, this causes an uncontrolled, usually large movement of the piston rod, which gives rise to unwanted handling problems with the dispenser. Depending on the actual dispensing forces, the manual force relief causes the piston rod to travel sometimes large, uncontrolled relief paths. These relief paths have to first be compensated for during the next dispensing procedures by executing several strokes on the dispenser, translating into additional work and time expenditure for the user. Moreover, this process is markedly disrupted in applications for which a specific number of strokes or specified piston rod movements are prescribed in order to expel the requisite mortar quantity, as is the case for applications in hollow substrates.
A targeted force relief or path relief for the piston rod and thus for the entire system after a dispensing procedure or after a stroke is difficult to implement in the mechanical dispensers that have a clamping-element drive and that are available on the market nowadays. Consequently, targeted force relief or path relief has not been implemented up until now.
It is an object of the present invention is to provide a dispenser that avoids the above-mentioned disadvantages by means of a controlled return stroke of the piston rod at the end of the stroke, thus ensuring a targeted path relief or pressure relief of packs containing pasty compounds.
The invention provides the idea of minimizing or even entirely preventing afterflow of mortar by means of a targeted force relief of the at least one piston rod after the dispensing procedure or after a stroke. In this manner, on the one hand, undesired contamination of the dispensers and of the work environment can be avoided and, on the other hand, disruption of the mixing or curing due to different levels of afterflow of the component compounds in multi-component systems can be prevented.
The present invention implements an at least partial pressure relief or force relief of all of the components in the single-component or multi-component packs and dispensers by means of a controlled return stroke of the piston rod after each dispensing stroke, which is made possible by a flexible force-controlled and/or path-controlled connection between the receptacle for the pack and the advancing mechanism with the piston rod. When it comes to a dispenser for a pack containing single-component or multi-component compounds having a receptacle for the pack, having at least one piston rod, and having an advancing mechanism for pushing the at least one piston rod in the direction of the receptacle, whereby the advancing mechanism has at least one clamping element that can engage with the piston rod and that can detachably clamp onto it in order to push the at least one piston rod, it is provided according to the invention that the advancing mechanism is movably joined to the receptacle for the pack in such a way that the advancing mechanism can be moved by means of the piston rod along the advancing axis out of a first position into a second position.
The advancing mechanism with the piston rod of the dispensers used up until now is firmly joined to the receptacle for the pack, so that after each dispensing stroke, the at least one clamping element is always returned to a defined initial position, for instance, by means of a spring or another mechanism, and the at least one piston rod is held by at least one additional clamping element in the position that is reached after the dispensing stroke. This prevents a return stroke of the piston rod opposite to the direction in which the pressure is exerted. In this manner, after each dispensing stroke, the at least one piston rod has a defined, fixed position in the pack used for the dispensing procedure. Consequently, after each dispensing procedure, the force or pressure in the system can only be relieved in the dispensing direction. This causes afterflow of the compound, which, in the case of multi-component compounds, can vary for each individual compound, depending on its specific compressibility/elasticity.
The advancing mechanism according to the invention, which comprises the at least one clamping element that serves to advance the at least one piston rod, is arranged in such a way that it is not rigidly joined to the receptacle, but rather so as to allow a movement relative to each other along the advancing axis, that is to say, between the receptacle for the pack and the advancing mechanism. Owing to the movement of the advancing mechanism, after a dispensing stroke, the at least one piston rod is no longer held in a fixed position with respect to the receptacle and thus with respect to the pack. This allows the advancing mechanism to be moved, and thus also the at least one piston rod, opposite to the direction of the stroke movement (return stroke), as a result of which the system can relax in the direction of the advancing mechanism. At the time of the next dispensing stroke, the return stroke then has to be compensated for by a longer path on the dispensing lever.
Advantageously, the advancing mechanism with the piston rod is movably joined to the receptacle for the pack in such a way that the advancing mechanism with the piston rod can be moved along the advancing axis out of a first position into a second position. This allows the advancing mechanism to be moved together with the at least one piston rod opposite to the direction in which pressure is exerted.
This movement can be carried out actively and/or passively. In this context, “passively” means that the movement is brought about only by the pressure or pressure forces that are present in the cartridge or film pack at the end of a dispensing stroke. The term “actively” means that the movement is caused by a force which does not come from the cartridge or film-pack system itself, but rather, which was exerted during the previous dispensing procedure in addition to the force needed to dispense the compound contained in the pack. An active movement is achieved in that, during the dispensing procedure, the advancing mechanism is at first at a certain distance from the receptacle for the pack and it has to be moved in the direction of the receptacle by means of the exertion of force. This is the case, for example, when a mechanism is provided between the advancing mechanism and the receptacle for the pack, so that when the advancing mechanism is pressed against the receptacle for the pack, said mechanism builds up a counterforce in order to press the two parts away from each other again after the dispensing stroke. Once the dispensing procedure has been completed, due to the relaxation of the previously applied additional force, that is to say, the counterforce, the advancing mechanism is actively pushed back opposite to the direction in which pressure is exerted. As an alternative, the advancing mechanism can be configured in such a manner that its return movement takes place without the exertion of additional force, so that the return movement is passive, exclusively due to the force stemming from the pack. Moreover, the movement can take place analogously to the active movement, whereby the advancing mechanism is arranged with respect to the receptacle in such a way that, in addition to the active movement, a passive return movement takes place, that is to say, caused by the pressure force that might still be present in the pack.
However, since the extra work for the user during the next dispensing procedure has to be minimized, the return stroke should only constitute part of the total dispensing stroke. For this reason, the movement path of the return stroke is preferably limited. Owing to this partial force relief or pressure relief in the pack used for the dispensing procedure, afterflow of the mortar can be reduced to such an extent that afterflow of compound is negligible or non-existent and, in the case of multi-component systems, there are no longer any disruptions of the mixing and curing of the compound dispensed from the mixing element.
Moreover, the expenditure of force in the system for purposes of moving the advancing mechanism opposite to the direction in which pressure is exerted has to be kept so small that the system can be relieved via the return stroke of the advancing mechanism rather than in the dispensing direction via the outlet opening of the pack and thus into the mixing element. For this reason, it is preferable for the movement path of the advancing mechanism as well as for the force required for the return stroke to be adjustable. In this manner, the return stroke can be controlled as a function of the system properties such as compressibility and dynamics (spring-damper behavior) and can therefore be kept as small as possible.
In the case of multiple-component compounds, for instance, which are only mixed with each other when they are dispensed out of the pack into a mixing element connected to the pack such as a static mixer, the dispensing forces and correspondingly the force relaxation after a dispensing procedure are relatively high, particularly in the case of pasty compounds. Consequently, a higher force can also be set for the return stroke. In the case of lower-viscosity compounds, the force for the return stroke has to be set correspondingly lower. The force needed to return the advancing mechanism to the initial position at the end of the dispensing stroke by relaxing the system must not be too high and should not require a noticeably higher force expenditure on the part of the user during the dispensing procedure. Advantageously, the movement force is set so low that it is independent of the system-related dispensing forces.
The advancing mechanism here can be provided in a component of its own, such as, for example, a housing.
Preferably, the advancing mechanism and the receptacle for the pack are joined together by a decoupling element (mechanical decoupling). The decoupling element is configured in such a way as to result in a path-controlled and force-controlled movement of the advancing mechanism and thus of the at least one piston rod opposite to the direction in which pressure is exerted. The decoupling element is not restricted. It merely has to be designed in such a way as to allow an active and/or passive movement of the advancing mechanism. Moreover, the decoupling element can be such that a path-controlled and/or force-controlled movement of the piston rod is ensured. Examples of decoupling elements are a carriage system, a disc spring or a plastic damper, or else a combination thereof.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described in greater detail below on the basis of an embodiment. The following is shown:

FIG. 1: a schematic top view of a dispenser according to the invention.

DETAILED DESCRIPTION

The dispenser 1 shown in FIG. 1 has a receptacle 2 for a cassette into which a pack having two film pouches arranged in parallel is inserted. The piston rods 3 for dispensing the compounds contained in the pack or in the cartridge are situated on the advancing mechanism 4 that is joined to the receptacle 2 by means of two decoupling elements in the form of damping elements 5 such as, for instance, plastic dampers. The damping elements 5 ensure the path-controlled and/or force-controlled return stroke of the advancing mechanism 4 along with the piston rods 3 for purposes of relieving the pressure or force in the pack.
In order to dispense the compounds from the pack, the piston rods 3 are moved axially via a schematically-shown clamping mechanism 14 in the direction of the receptacle 2 by actuating a lever on the advancing mechanism 4. In this process, the damping elements 5 are compressed so that first of all, the entire advancing mechanism is moved in the direction of the receptacle 2, as a result of which the advancing mechanism 4 is moved out of a first position into a second position. The distance that has to be travelled during the stroke can be set by means of the damping element itself, by the material properties, by the size and thickness, relative to the advancing direction of the piston rod. Once the advancing mechanism 4 is no longer resting movably on the receptacle 2, the further stroke movement of the anchor rods 3 causes a further rise in the force or pressure in the pack used in the dispensing procedure, thus causing the compound to flow out into the static mixer.
After the dispensing stroke has been completed and after the lever has been released, the damping elements 5 press the advancing mechanism 4 in the direction opposite to the dispensing direction, that is to say, away from the receptacle 2, for example, as a result of which the advancing mechanism with the piston rod is once again moved out of a first position (previously the second position) into a second position (previously the first position). As a result, the pressure in the pack used for the dispensing procedure can be relieved partially directly and afterflow of the compounds contained in the pack for relieving the pressure and force can be prevented or minimized. The magnitude of the return stroke, in other words, the movement path opposite to the dispensing direction, is determined on the basis of the properties of the damping element 5. When elastic plastic dampers 5 are used, the distance of the return stroke can be greater than the thickness of the plastic dampers, so that an additional force relaxation of the system can be achieved passively. This effectively prevents afterflow of the compounds contained in the pack.

Claims

What is claimed is:

1. A dispenser for at least one pack containing a single-component or multi-component compound, the dispenser comprising:

a receptacle for the pack;

at least one piston rod; and

an advancing mechanism for moving the at least one piston rod in a direction of the receptacle so as to define an advancing direction, the advancing mechanism having at least one clamping element engageable with the piston rod and detachably clampable to the at least one piston rod in order to move the at least one pison rod, the advancing mechanism with the piston rod being movably joined to the receptacle for the pack in such a way that the advancing mechanism with the piston rod can be moved along an advancing axis out of a first position into a second position relative to the receptacle.

2. The dispenser as recited in claim 1 wherein the advancing mechanism is joined to the receptacle for the pack in such a way that the advancing mechanism, together with the at least one piston rod, is movable opposite to the advancing direction.

3. The dispenser as recited in claim 2 wherein the advancing mechanism is movable at least one of actively and passively.

4. The dispenser as recited in claim 1 wherein the advancing mechanism and the receptacle for the pack are joined together by at least one decoupling element.

5. The dispenser as recited in claim 4 wherein the at least one decoupling element allows a path-controlled and force-controlled return stroke of the piston rod opposite to the advancing direction.

6. The dispenser as recited in claim 5 wherein the at least one decoupling element is a carriage system, a disc spring or a plastic damper.

7. The dispenser as recited in claim 4 wherein the at least one decoupling element is a carriage system, a disc spring or a plastic damper.