Agitating – Having specified feed means – Liquid injector within mixing chamber
Reexamination Certificate
2000-11-13
2003-02-25
Cooley, Charles E. (Department: 1723)
Agitating
Having specified feed means
Liquid injector within mixing chamber
C366S312000, C366S326100, C366S329100, C222S145600
Reexamination Certificate
active
06523992
ABSTRACT:
BACKGROUND OF THE INVENTION
The instant invention relates to a device for mixing two pasty substances, particularly for mixing a dental impression substance (basic substance) and a catalyst substance for initiating and/or accelerating the polymerization of the dental impression substance.
A device of the above type is mounted onto the outlet connector of a dispensing device by which, through application of pressure onto the pasty substances contained either in cartridges or in film hose packs, these substances are introduced into the mixing device and after mixing in the mixing device are issued therefrom as a mixture.
In a large number of technical uses, it is required that two pasty substances, which have been stored separate from each other, are applied in mutually mixed form. For this purpose, use is made either of dynamic or static flow mixers designed to mix the pasty substances with each other while these are flowing through the mixer housings.
A dynamic mixer is known e.g. from EP-A-0 492 412. This known device comprises a substantially tubular mixer housing with a mixer shaft arranged for rotation therein. The mixer shaft is provided with a plurality of radially projecting vane-shaped mixing elements for mixing the pasty substances with each other when the mixer shaft is driven. The pasty substances enter the mixer housing via a radial end wall at the rear end of the mixer housing. For this purpose, the end wall is provided with two inlet connectors arranged to be mounted onto the outlet connectors of a device for delivery of the pasty substances. The two inlet openings of the end wall through which the pasty substances enter the mixer housing, are arranged diametrically opposite each other and are axially oriented relative to the mixer shaft. Thus, the two sites where the pasty substances enter the mixer chamber are arranged at a considerable distance, making the mixing process more difficult.
Known from EP-A-0 885 651 is a static mixer wherein a mixer chamber includes a plurality of mixing elements behind each other and in fixed positions. The two pasty substances to be mixed enter the mixer chamber via separate inlet openings. These openings are arranged on diametrically opposite sites of the mixer housing. One of the two pasty substances is caused to reach the inlet openings for the other pasty substance along a curved channel and will then together with the other substance into the actual mixer chamber having the mixer elements arranged therein. Thus, the two pasty substances will enter the mixer chamber of the mixer housing together through the same inlet openings. This causes a danger of backward contamination, i.e. a contamination spreading in reverse flow direction, with the possible result that at least one of the two pasty substances is hardened up into the outlet connector of the dispenser device so that, from this point of time, no pasty material can be discharged from the respective film hose bag or the respective cartridge and the pasty substances still remaining in the cartridge or the film bag hose cannot be used anymore.
It is an object of the invention to provide a device for mixing two pasty substances which guarantees a largely homogeneous mixing of both substances.
SUMMARY OF THE INVENTION
According to the instant invention, the above object is achieved by a device for mixing two pasty substances, particularly for mixing a dental impression substance with a catalyst substance, comprising
a housing comprising a substantially tubular portion and at least two inlet openings for the two pasty substances at the rear end of said housing, and an outlet opening for the mixed pasty substances at the front end of said housing,
said housing being provided with a coupling portion joining said tubular portion and having two coupling openings formed therein for connecting the housing with two outlet openings of a device for dispensing the two pasty substances, and
said coupling openings being connected to said inlet openings via first and second channels extending through said coupling portion, and
at least one mixer element arranged within said tubular portion of the housing for mixing the two pasty substances when the substances are passing through the tubular portion of the housing.
According to the invention, the above device is characterized in that
said first channel or said second channel or both of said channels extend to at least two inlet openings,
said inlet openings are spatially separated from each other, and
said first channel or said first channels are separated from said second channel or said second channels.
Thus, according to the general idea of the invention, it is provided that all of the pasty substances are introduced via separate inlet openings into the actual mixer chamber of the mixer housing. Therefore, no mutual mixing or contacting of the pasty substances will occur prior to passing these inlet openings. Further, at least one of the two inlet openings will enter the mixer chamber of the mixer housing via more than one inlet opening. Particularly, this mixer chamber is said substantially tubular portion of the mixer housing. The connection of the inlet openings to the coupling openings of the mixer housing which are preferably formed as connecting studs, is established via channels extending from the coupling openings to the inlet openings. Thus, at least one of the two channels leads from the appertaining coupling opening to a plurality of inlet openings. For this purpose, this channel can be configured to split into individual partial channels which under the aspect of flow technology are connected in parallel and terminate in the inlet openings. By way of alternative, a plurality of inlet openings can be arranged along the extension of the channel, connecting the channel with the actual mixer chamber of the mixer housing. Thus, in this case, the inlet openings are arranged in a row.
A further variant of a channel leading to more than one inlet opening resides can be realized by a distributor channel which is connected to the appertaining coupling opening and is connected via inlet openings to the actual mixer chamber of the mixer housing.
By introducing at least one of the two pasty substances into the mixer chamber at a plurality of separate sites, an improved mixing of the two pasty substances is obtained. The reason is to be seen in that the substance flow of said one pasty substance is divided among a plurality of inlet openings of the tubular portion of the housing and the mixer chamber, respectively. The improved mixing is achieved without a mutual contact of the two pasty substances occurring already prior to entry into the mixer chamber. This is advantageous if it is desired to prevent backward contamination.
According to a preferred embodiment of the invention, it is provided that one of the two channels extends to a sole inlet opening and the other channel extends to two inlet openings. Thus, the mixer chamber comprises three inlet openings altogether. Preferably, these inlet openings are distributed in a uniform configuration. This uniform distribution can be provided either in the circumferential direction or in the axial direction of the mixer chamber. Even if more than three inlet openings are provided, and irrespective of the numerical distribution of these inlet openings among the two channels, it will be of particular advantage if all of the inlet openings are distributed in a uniform configuration.
The orientation of the inlet openings relative to the actual mixer chamber, i.e. relative to the substantially tubular portion of the housing, can be substantially radial and/or substantially axial. Further, it is possible to provide both radial and axial inlet openings.
The inventive concept of introducing at least one of the two substances on a plurality of spatially separated sites of the mixer chamber can be realized both in a static and a dynamic mixer, i.e. in a mixer with stationary mixer elements as well as in a mixer with rotary mixing elements.
To prevent that a pasty substance entering the mixer chamber fr
Bublewitz Alexander
Suchan Matthias
Cooley Charles E.
Diller Ramik & Wight
Kettenbach GmbH & Co. KG
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