Apparatus for dispensing a mixed multi-component compound, in particular for dental purposes

Apparatus for dispensing a mixed multi-component compound, in particular for dental purposes. The adjacent outlet connection stubs of the component-containing containers bear a coupling plate on the end sides for the purpose of connecting a mixing nozzle. Said coupling plate forms a guide, running transversely to the direction of the outlet connection stubs, for a coupling slide with a coupling element which engages over a coupling flange provided on the mixing nozzle. The slide is in the form of a frame and is arranged permanently on the coupling plate.

BACKGROUND INVENTION
 The invention relates to an apparatus for dispensing a mixed
 multi-component compound, in particular for dental purposes.
 For producing multi-component dental impression compounds, use is made of
 units which are designed for accommodating a plurality of
 component-containing containers and for discharging the components from
 the containers. On the end side of the units, the containers have exposed
 outlet openings, to which the inlet openings of a mixing nozzle may be
 connected. The components come together in the mixing nozzle and leave the
 latter in the mixed state. Following the mixing operation, the compound
 hardens. This also applies to those components of the mixture which remain
 in the mixing nozzle once an impression-compound portion has been
 produced. Said mixing nozzle is configured such that the components only
 come together therein at a certain distance from the outlet openings of
 the cartridges, with the result that the hardening operation within the
 mixing nozzle remains restricted to a region sufficiently remote from the
 outlet openings of the containers. This makes it possible for a mixing
 nozzle which is used for producing an impression-compound portion and is
 rendered unusable by some of its contents hardening to be left on the unit
 in order to protect the outlet openings until the next portion is
 required. It is only then that the mixing nozzle is exchanged for a new
 one.
 In a known unit disclosed in U.S. Pat. No. 5,333,760 the mixing nozzles are
 retained by a rotatable bayonet closure. A bayonet ring is retained on the
 mixing nozzle in an axially fixed but rotatable manner and, following the
 attachment of the nozzle to the outlet openings of the containers, is
 rotated in order to come into positively locking engagement with a pair of
 claws on the end side of the containers. The ring involves high outlay in
 terms of its connection to the mixing nozzle and because a comparatively
 large number thereof is required, specifically one for each mixing nozzle.
 This applies correspondingly to another known arrangement (EP-A-730 913),
 in which the bayonet coupling elements are arranged on the mixing-nozzle
 housing, which contains, in a rotatable manner relative to the housing, an
 insert which forms the inlet opening of the mixing nozzle. A design
 (DE-U-298 20 831) in which a locking means is arranged on the unit for the
 purpose of retaining the mixing nozzle involves less outlay. This means
 that it is not necessary for each individual mixing nozzle to be equipped
 with a bayonet element. However, it has been found that this design does
 not afford sufficient stability.
 The apparatus according to FIG. 4 from U.S. Pat. No. 4,753,536 comprises
 two component-containing containers which are fixed to one another and
 bear outlet connection stubs adjacent to one another on the end sides. It
 is possible to fit onto the outlet connection stubs a mixing nozzle which
 can be secured in the fitted position by a coupling device. The coupling
 device comprises a coupling plate which is borne by the outlet connection
 stubs and forms a guide, running transversely to the direction of the
 outlet connection stubs, for two coupling slides. The latter can be
 displaced into a closed position on the guide in opposite directions and
 bear coupling strips which, in the closed position, engage over a coupling
 flange of the mixing nozzle through 180.degree. in each case.
 SUMMARY OF THE INVENTION
 The object of the invention is to provide an apparatus of the type
 mentioned in the introduction which has improved handling.
 For this purpose, provision is made for the coupling slide to be in the
 form of a frame, and for displacement from the closed position into an
 open position, in which the coupling strips are free of the coupling
 flange, to be limited by contact with the coupling slide on a frame side.
 The actuation of one coupling slide means reduced outlay in comparison with
 the actuation of two coupling slides, as in U.S. Pat. No. 4,753,536.
 Contact with the coupling slide on a frame side provides a defined open
 position, which allows the mixing nozzle to be attached to the outlet
 connection stubs and also allows the removal of the mixing nozzle. In the
 open position, the coupling slide remains on the unit and does not have to
 be attached laboriously again for a renewed closing operation.
 Considerably easier handling is achieved overall.
 On its side which is directed towards the plate, the mixing nozzle is
 preferably bounded by a surface which rests over a large surface area on
 the surface of the plate.
 Since the coupling plate is arranged directly on the containers and/or the
 connection stubs thereof, positional tolerances between the containers and
 the unit do not affect the securing of the mixing nozzle. Rather, the
 coupling forces are transmitted over an extremely short distance from the
 mixing nozzle to the outlet connection stubs. This makes it possible for
 the relevant components to be of less rigid design, consequently involving
 less outlay, than if the force transmission were to extend over a larger
 distance.
 In the closed position, the coupling slide grips, by means of its coupling
 elements, the coupling flange of the mixing nozzle in such a way that the
 mixing nozzle is retained in sufficiently firm and sealed abutment against
 the outlet connection stubs and/or the coupling plate. Said coupling
 flange is gripped at least at two points which are offset by 180.degree.
 in relation to one another. The coupling action expediently covers an
 angle of at least 180.degree., with the result that the coupling flange
 does not lack support over more than 180.degree.. If a plurality of grip
 points are provided, these are spaced apart from one another by not more
 than 180.degree.. If a single coupling element, which covers the border of
 the coupling flange continuously, is provided, this has to extend over at
 least 180.degree. . If a plurality of coupling elements are provided, this
 is not necessary.
 In one embodiment of the invention, the guide for the coupling slide is
 formed by two parallel strips on the coupling plate and two strips,
 engaging behind the same, of the coupling slide. The latter can thus be
 displaced in a translatory manner transversely to the direction of the
 outlet connection stubs. The guide strips are expediently continuous. Of
 course, however, it is also possible for in each case one of these to be
 made up of a plurality of spaced-apart protrusions. The slide has coupling
 strips in its region which interacts with the coupling flange of the
 mixing nozzle in the closed position. If, following the attachment of the
 mixing nozzle, the slide is pushed into its closed position, then the
 coupling strips are pushed over that part of the mixing-nozzle coupling
 flange which is adjacent to them in each case and thereby prevent the
 mixing nozzle from moving away from the coupling plate. As a result, the
 mixing nozzle is secured in the coupled position.
 In a further embodiment, the coupling plate and the coupling flange have
 corresponding and adjacent coupling borders, and there is provided a
 coupling slide which can be pushed over the two borders, from the side, in
 order to enclose the same in the closed position of said coupling slide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The unit 1 contains a mount 2 and an emptying drive for two containers 3, 4
 which contain the components of a dental impression compound. The
 components are discharged by way of a mixing nozzle 5, from which said
 components emerge as a mixed, ready-to-use tooth-impression compound.
 As can be seen in FIG. 2, the containers 3, 4 are fixed to one another via
 suitable material bridges 6. Each container 3, 4 has a respective outlet
 connection stub 7, 8, which opens out in an outlet opening 9, 10,
 respectively. These openings are located in a coupling plate 11, which is
 fixed to the outlet connection stubs 7, 8. It would also be sufficient if
 said coupling plate were connected to just one outlet connection stub,
 provided that the latter is sufficiently strong and rigid in order also to
 ensure the desired position of the coupling plate 11 in relation to the
 other outlet connection stub. The coupling plate 11 contains a central
 opening 12 through which a drive shaft for driving the mixer shaft of a
 dynamic mixer may be routed if desired. Since this is known, it will not
 be explained in any more detail here.
 As can be seen in FIG. 3, the coupling plate 11, on two opposite, parallel
 sides, has guide grooves 13 between guide strips 24, which run parallel to
 one another and to the plane of the coupling plate 11. They serve for the
 guidance connection to the slide 14 (FIG. 4). The latter is in the form of
 a frame. Two frame sides 15 each bear a guide strip 16 on their mutually
 facing inner sides. The dimensions and spacings of the guide strips 16
 match the guide grooves 13 of the guide plate 11. The slide can be pushed
 onto the guide plate 11 with its side which appears on the right in the
 drawing in front. Its allowance for movement in relation to the guide
 plate 11 is then given by its third frame side 17 and a stop 18 on the
 fourth frame side 19. The stop 18 is designed such that it can yield
 elastically when the slide is pushed onto the coupling plate 11, but
 prevents the undesired action of the slide sliding off the coupling plate
 11. The coupling slide 14 is expediently provided with grip hollows 20 or
 the like for easier displacement in relation to the coupling plate 11.
 FIG. 5 illustrates the slide 14 fitted on the coupling plate 11, to be
 precise in the open position of the slide, in which the mixing nozzle 5
 can be fitted onto the coupling plate 11 and removed therefrom. The inlet
 openings of the mixing nozzle are designed in relation to the outlet
 openings 9, 10 in the coupling plate such that there is a sealed
 connection when the coupling flange 21 of the mixing nozzle butts against
 the surface of the coupling plate 11.
 In that part of the slide which is on the right (in the drawing), the frame
 parts 15 are provided with coupling strips 22 which, when the slide is
 pushed into its closed position (FIG. 6), engage over those border regions
 of the coupling flange 21 which are adjacent to them. The distance between
 the underside of the coupling strips 22 and the surface of the coupling
 plate 11 is selected such that the coupling flange 21 is retained firmly
 on the coupling plate 11. In order that the slide 14 can easily be pushed
 from the open position into the closed position, the undersides of the
 coupling strips 22 are bevelled slightly at the opening end 23 of the
 same.