Fluid handling – Systems – Flow path with serial valves and/or closures
Reexamination Certificate
1999-01-15
2001-01-09
Chambers, A. Michael (Department: 3753)
Fluid handling
Systems
Flow path with serial valves and/or closures
C251S212000, C251S329000
Reexamination Certificate
active
06170521
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a shut-off device for pipelines and hoselines, generally called conduits herein, whereby the shut-off device includes a housing with a flow passage therethrough and at least one shut-off element arranged in the housing.
BACKGROUND INFORMATION
Shut-off devices of the above mentioned general type are used to control the flow of a conveying fluid, such as air, another gas, or a liquid, and a loose bulk material being conveyed by the conveying fluid in a hoseline or a pipeline or some other type of conduit, for example in a pneumatic conveyor system. In other words, such shut-off devices serve to open and close the conveyor conduit in a controlled manner. Generally, such shut-off devices are used in pneumatic conveyor conduits that convey plastic granulates and the like to various processing machines, whereby for example, a respective shut-off device is opened in order to fill a supply hopper or the like with the loose bulk plastic granulate, and is then closed once the required amount of material has been conveyed.
The conveyed material is generally not absolutely homogeneous in terms of particle size and the nature or quality thereof. Such inhomogeneity applies especially, but not exclusively, to recycled materials. The particulate nature of the conveyed materials, and the inherent inhomogeneity of the particle size and shape and other parameters of the material, lead to problems in the operation of the shut-off devices. For example, when the shut-off device is to be closed, not only the conveying air-stream, but also the flow of conveyed material itself must be blocked or shut off. As a result of the bulky materials becoming caught or hung-up as the shut-off element of the shut-off device is closing, it often becomes necessary to apply a considerable closing force to the shut-off element, especially when particles of the conveyed material must be pinched off by the shut-off element.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the invention to provide a shut-off device that can be reliably and consistently closed to block a conveyed stream of bulk material, while requiring only a relatively low application of closing force compared to the prior art, even when otherwise problematic bulk goods are being conveyed. Another object of the invention is to provide a closing element arrangement that does not cause pinching-off of particles of the conveyed goods. The invention further aims to avoid or overcome the other disadvantages of the prior art, and to achieve additional advantages, as apparent from the present description.
The above objects have been achieved in a shut-off device according to the invention, including a housing having a flow passage therethrough, and at least one shut-off element arranged in the housing so as to be movable between a first position in which the flow passage is substantially open to allow a flow therethrough, and a second position in which the shut-off element partially, but not completely closes the flow passage. The flow passage being “substantially open” in the first position means that the shut-off device has its nominal maximum flow cross-sectional area in the first position. On the other hand, the shut-off element is configured and/or arranged and/or movable in such a manner that when it is in its most-closed position, i.e. the second position, it does not completely close the flow passage. More particularly, the shut-off device is so embodied that a complete closure or blocking of the flow passage by the shut-off element is positively prevented.
According to the invention, the flow passage remains slightly open even when the shut-off element is in its most-closed position, whereby a flow gap remains through the flow passage in the area of the edge of the shut-off element, for example. The width of this flow gap is preferably on the same order of magnitude and more preferably within the range of one-half to one and one-half times the average particle size of the bulk material being conveyed. With this arrangement, the particles of the loose bulk material become caught or hung-up on the edges of the gap or within the gap and thereby serve to close the gap and complete the closure of the shut-off device, Alternatively, the remaining open gap width can be specified as being in the range from 0.5 mm to 40 mm for many applications, or as providing a remaining gap area of 1% to 7% of the nominal maximum open flow cross-section area of the flow passage. In the above manner it is achieved that the forces needed for closing the inventive shut-off element are significantly less than the forces needed for closing prior art shut-off devices, namely shut-off devices in which the shut-off element is completely closed and thereby has to pinch-off and separate the stream or even the individual particles of the conveyed bulk material.
According to a further embodiment of the invention, at least two shut-off devices are arranged in series one after the other in the conveying direction to form a shut-off system or shut-off arrangement. Preferably, the two shut-off devices are arranged vertically one above the other. In this shut-off arrangement, the conveyed stream of bulk material can first be interrupted or shut-off by the first shut-off device, and then the second shut-off device provides the complete airtight closure of the conveyor conduit line. Namely, the first shut-off device in this arrangement is preferably a shut-off device according to the invention in which the shut-off element does not completely close the flow passage, even in its most-closed position, while the second shutoff device may be any type of shut-off device that completely closes or seals the flow passage therethrough. This arrangement allows the conveying flow to be completely shut-off using relatively small shut-off elements driven by correspondingly small drive mechanisms that apply a relatively small closing force, in comparison to prior art arrangements.
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Mueller Peter
Rohr Marcel O.
Chambers A. Michael
Colortronic GmbH
Fasse W. F.
Fasse W. G.
McShane Thomas L.
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