Conveyors: fluid current – Intake to fluid current conveyor – Upstream of suction source
Reexamination Certificate
1999-08-06
2001-07-31
Ellis, Christopher P. (Department: 3651)
Conveyors: fluid current
Intake to fluid current conveyor
Upstream of suction source
C406S144000
Reexamination Certificate
active
06267540
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for generating a powder- air mixture, having a delivery device for the powder and a feed pipe for the conveying air.
BACKGROUND OF THE INVENTION
Such devices for mixing a powder with conveying air are sufficiently known. In connection with this, compressed air, for example, is blown into a storage container, the powder stored therein is swirled and a part of the swirled powder is carried out. It is disadvantageous in connection with this device that the amount of powder carried out is greatly dependent on the fill state of the container. However, it is desired that a constant amount of powder be carried out permanently, or at least over a very long period of time, so that fluctuations in the application of the powder to printed sheets of paper are prevented. Moreover, with these devices, the powder-air mixture is difficult to vary, or respectively to adjust it to changing outside conditions.
SUMMARY OF THE INVENTION
The object of the present invention is therefore based on making available a device of the type mentioned at the outset, by means of which the powder-air mixture can be relatively simply adapted to changing outside conditions. It is moreover intended to prevent the powder from being deposited on areas of the noted device and to cake there.
In accordance with the present invention, this object is attained in connection with a device of the type mentioned at the outset in that a device for forming an enveloping air jet for the conveying air is provided, and that the delivery device for the powder terminates in the device for forming an enveloping air jet; and therefore in the enveloping air jet.
It is provided with the device of the present invention that the conveying air is embodied in the form of an enveloping air jet, into which the powder is introduced, in particular aspirated. Here the Venturi principle is advantageously used, in that in the course of the air being formed into an enveloping air jet it is accelerated to high speed, so that the powder is entrained in it. The enveloping air jet prevents the powder from caking on the walls and causing interruptions. In the air mixture the powder is slowly mixed with the conveying air and carried out with it onto sheets of paper.
In connection with a further development it is provided that a feed pipe for the conveying air is arranged orthogonally with respect to the delivery device for the powder. This arrangement permits a space-saving construction, and the present device of the invention can be attached directly, for example underneath, a metering device.
In accordance with the present invention, the feed pipe for the conveying air is formed by a pipe connector. This pipe connector has been rigidly inserted into the delivery device, or is respectively fastened on it, in particular pressed into it. A compressed air hose or the like, through which compressed air is supplied, for example from a compressor, can be connected with this pipe connector, for example.
In a further development it is provided that the delivery device for the powder is constituted by a funnel which, while maintaining an air gap, terminates in an air conduit. Powder is filled into this funnel, for example by a fixed metering device, and falls into the air conduit under the action of gravity. The conveying air is conducted through the lateral distance between the air conduit and the funnel, surrounds the delivery opening of the funnel as an enveloping air jet and picks up the powder, or respectively entrains it. The powder is aspirated from the funnel, so to speak.
In order to achieve the greatest possible air distribution over the entire circumference of the delivery opening of the funnel, the pipe connector terminates via a distributing chamber into the air conduit. The distributing chamber is enclosed, for example, in a sleeve, and sealed against the outside. Initially, the air rises opposite the delivery direction from this distributing chamber, is radially reversed toward the inside and then comes between the funnel and the air conduit, where the enveloping air jet is formed.
The air conduit preferably terminates in a distributing pipe. This distributing pipe widens conically in the delivery direction. By means of this, a reduction of the flow speed is achieved, and moreover the fact, that the powder sticks to the inside of the distributing pipe and cakes there, is counteracted.
In accordance with the present invention, the components are designed as elements turned on a lathe and can therefore be produced relatively simply and cost-effectively.
A further preferred embodiment provides that the axis of the feed pipe for the conveying air and the longitudinal plane of symmetry which is parallel in relation to this axis, are offset with respect to each other. In this way the conveying air is introduced into the delivery device in a decentralized manner, and a spin is forced on it in this way. Therefore the air flows through the distributing chamber also in the circumferential direction, and the enveloping air jet has a spin as a result of this. This spin has the advantage that the enveloping air jet is more stable and does not dissolve as rapidly. In this way the interior wall of the air conduit, as well as that of the distributing pipe, are, inter alia, protected against wear by abrasive powder. Moreover, the operating, or respectively flow noise, are considerably reduced. In addition, the powder is better distributed in the conveying air.
Alternatively or additionally, the delivery device, in particular the air conduit, has air guide devices, for example, spin strips, helical grooves, or the like. By means of these air guide devices it is also possible to force a spin on the air flowing by.
A further advantage of the device of the present invention is seen to be that there is a short distance between the metering device located above the device and the aspirating place at the end of the funnel, which results in extremely short response times, if a clock control of the powder feed is possibly provided.
Further advantages, characteristics and details of the present invention ensue from the following description, in which a particularly preferred exemplary embodiment is described, making reference to the drawings. The characteristics represented in the drawings and mentioned in the claims, as well as in the specification, can here be essential for the present invention, either respectively by themselves or in any arbitrary combination.
REFERENCES:
patent: 4807814 (1989-02-01), Douche et al.
patent: 5615980 (1997-04-01), Mauchle
patent: 5645380 (1997-07-01), Rutz
patent: 5676494 (1997-10-01), Ruch
patent: 5873680 (1999-02-01), Huber et al.
Ellis Christopher P.
Jillon, Jr. Joe
Jones Tullar & Cooper P.C.
Weitmann & Konrad GmbH & Co. KG
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