Conveyors: fluid current – Intake to fluid current conveyor – Load receptacle type
Reexamination Certificate
1998-10-05
2001-06-05
Ellis, Christopher P. (Department: 3651)
Conveyors: fluid current
Intake to fluid current conveyor
Load receptacle type
C406S198000
Reexamination Certificate
active
06241428
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for dusting moving printed sheets, and more particularly to a reservoir for powder used in the device. The reservoir for powder, having an inlet for a carrier air flow terminating in the reservoir and an outlet from the reservoir for the carrier air flow loaded with powder.
BACKGROUND OF THE INVENTION
A device for dusting printed sheets is known, for example from German Published, Examined Patent Application DE-AS 12 52 703, or respectively from German Patent 966 443, wherein a carrier air flow is blown into a container filled with powder so that, although this carrier air flow can be enriched with powder, the proportion of powder in the carrier air flow is greatly dependent on the level of the powder in the reservoir. Considerably more powder is stirred up when the container is full than with an almost empty reservoir, where merely 50% of the initial amount is carried away. Similar devices are known from German Patents 926 910, 913 781 and 969 862.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to make available a device of the type mentioned at the outset, wherein the delivery rate of the powder depends less on the level of the powder stored in the reservoir.
In connection with a device mentioned at the outset, this object is attained in accordance with the present invention in that the reservoir is divided into sections including a delivery chamber and a storage chamber by means of a separating wall, and the inlet and the outlet communicate with the delivery chamber, and the storage chamber is used for filling the delivery chamber.
By means of the device in accordance with the present invention, the essential advantage is achieved that the loading of the carrier air is considerably more even and constant and only minimally depends on the level of the powder in the reservoir. This is achieved in that the reservoir is divided into two chambers, and the powder is delivered by means of the carrier air only out of one of these chambers, namely the delivery chamber. This delivery chamber has an almost constant powder level, since powder permanently flows in from the storage chamber into the delivery chamber. When the level of the powder in the storage chamber reaches a lower limit, the storage chamber must be refilled. Since the powder delivery can be maintained essentially constant over a relatively long period of time, the carrier air flow can now be adjusted in such a way that the optimal amount of powder is delivered. A further advantage of the present invention lies in that it is now possible to embody the reservoir considerably larger. With the prior art a very large reservoir was impossible, since in that case the difference between the maximum and minimum delivery rate, which would have increased with the size of the reservoir, would be unacceptably large.
A further development provides that the dividing wall has a control edge, which determines a defined connection cross section between the delivery chamber and the storage chamber. With an initially full reservoir, and therefore also a full delivery chamber, the control edge is used for guiding a portion of the carrier air flow, which is blown on the powder surface and is deflected in a tangential direction, into the storage chamber. If this control edge is formed by at least a section of the upper edge of the dividing wall, the carrier air flow is divided into two partial flows, wherein the one partial flow is guided in the tangential direction via the control edge out of the delivery chamber and steered into the storage chamber. The second partial flow leaves the delivery chamber through the outlet. By means of this division of the carrier air flow into two partial flows the advantage is achieved that the carrier air flow, which initially is loaded with relatively much powder, is not completely taken to the outlet, but only a portion of the carrier air flow. The other portion, which is also laden with powder, reaches the storage chamber, where the powder which is carried along settles. The level of the powder in the delivery chamber is slowly lowered, which leads to the carrier air flow not impacting on the surface of the powder immediately after leaving the inlet, but instead it must travel a certain distance. This leads to the carrier air flow being less strongly deflected in the tangential direction, so that because of this the partial air flow leaving the delivery chamber to pass into the storage chamber is considerably less. Since, along with the lowering level of the powder in the delivery chamber, the loading of the carrier air flow with powder also becomes less, this reduced load is compensated for by a smaller partial air flow being deflected. The amount of powder which is carried along and leaves the delivery chamber together with the other partial air flow through the outlet therefore is essentially as large as it originally was. In this way the reduced loading of the carrier air flow because of the lowering powder level is compensated for by the partial air flow being deflected over the control edge into the storage chamber becoming smaller.
The outlet is advantageously arranged in the area of the control edge, and the inlet and the outlet in the delivery chamber are placed diagonally opposite each other. Because of the relatively large distance between the inlet and the outlet, discrete partial flows can form, wherein the tangential flow moves past the outlet and leaves the delivery chamber and flows into the storage chamber, and the other partial flow, because of its orientation, leaves the delivery chamber through the outlet, carrying along the appropriate amount of powder. Since the inlet is arranged in the immediate vicinity of the separating wall, after impinging on the powder surface the carrier air flow is forced to flow in the tangential direction toward the outlet. The sooner the carrier air flow impinges on the powder surface, the greater the tangential air flow is, which is the case with the delivery chamber being relatively full. If the level in the delivery chamber is lowered, the tangentially flowing partial air flow is also reduced, and the partial air flow in the axial direction is increased.
The inlet and/or the outlet advantageously terminate in the delivery chamber, or respectively leave the delivery chamber, vertically. By means of this the partial air flow is guided directly onto the surface of the powder in a known manner, so that the powder is stirred optimally, or respectively maximally.
It is provided in accordance with one variant of the present invention that the separating wall is connected with the reservoir. With another embodiment the separating wall is arranged on a cover which closes off the storage chamber. This embodiment is preferred, since the inlet and the outlet are also provided on the cover. In this way it is possible to set optimal flow conditions between the inlet, the outlet and the separating wall, which are also retained when removing and then replacing the reservoir again, i.e. they need not be set anew.
Different configurations of the separating wall are conceivable. Thus, the separating wall can be made of one or several pieces and/or curved and/or beveled and/or embodied to extend over the height of the reservoir. It is also conceivable for the separating wall to extend over only a portion of the height of the reservoir, so that the delivery chamber and the storage chamber communicate with each other at the bottom of the reservoir.
It is provided in connection with an exemplary embodiment for the separating wall to have overflow openings for the powder. After reaching a defined powder level, the delivery chamber is charged with powder from the storage chamber through these overflow openings which, for example, are embodied triangularly and taper acutely toward the top. The flow of the powder from the storage chamber into the delivery chamber takes place automatically, since the reservoir performs shaking movements generated by the actuation of air valves. However
Dillon, Jr. Joe
Ellis Christopher P.
Jones Tullar & Cooper P.C.
Weitmann & Konrad GmbH & Co. KG
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