Dispensing – With discharge assistant – Movable or conveyer-type trap chamber
Reexamination Certificate
2000-07-20
2001-09-25
Kaufman, Joseph A. (Department: 3754)
Dispensing
With discharge assistant
Movable or conveyer-type trap chamber
Reexamination Certificate
active
06293439
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a high pressure rotary valve suited for use in the conveying or feeding of flowable, or pelletized granulated bulk material, friable products, fine powders, and the like. A pneumatic system of positive blowers and negative pressure means is normally used for imparting the conveying forces needed for moving the material to and from the valve outlet through the system.
Valves of the type contemplated include a housing defining a chamber and having a top inlet and a bottom outlet communicating with the chamber. Within the housing chamber there is provided a rotor which includes a plurality of blades supported on a horizontal shaft. The material being conveyed is fed to the housing inlet and then into the spaces defined between the blades. The rotor movement conveys the material to the outlet location of the housing for discharge of the material from the housing. Since the rotor speed can be controlled, the valve serves as a means for regulating the rate at which the material is conveyed in the feed line extending from the housing outlet to the equipment being supplied with the material.
It is important to provide means for sealing of the housing chamber so that the material being conveyed does not penetrate into regions where there are relatively movable parts, such as the area occupied by the rotor shaft which moves relative to bearings mounted in the housing. Such penetration, particularly in the case where relatively abrasive materials are being handled, can cause undue wear of parts and excessive downtime for replacement thereof.
Critical to efficient and consistent material flow through the pneumatic system, as well as maintaining material integrity, is the sustaining of line gas flows. Rotor, housing and bearing arrangement and assembly methodology are critical to prevent loss of mass and volumetric gas flow. When left unchecked, such drops in gas flow adversely effect material conveyance throughout the system.
The use of seals is also important for purposes of preventing leaking of the material being conveyed into the atmosphere surrounding the housing. This is particularly the case where toxic materials or the like are being conveyed.
The provision of adequate sealing arrangements is often problematical due the fact that the material is being conveyed under high pressure conditions, thereby increasing the tendency for movement of the material axially with respect to the rotor shaft rather than towards the discharge end of the housing. Packing glands and O-ring arrangements have been designed with a view toward eliminating or minimizing such problems, however, such prior art arrangements have been proven to be either unduly expensive, have been subject to frequent maintenance, have been ineffective, or have been characterized by a combination of these problems.
SUMMARY OF THE INVENTION
The rotary valve of this invention is of the type comprising a housing defining a material holding chamber and having an inlet at the top end and an outlet at the bottom end communicating with this chamber. In a typical system, granulated bulk material will be delivered to the inlet location and then moved through the housing chamber to the outlet for passage into a line leading to processing equipment for the material. Within this chamber there is provided a rotor carrying a plurality of spaced apart blades, and the material is carried within the spaces between the blades from the inlet to the outlet of the housing. In this manner, the rate at which the material is conveyed in the line leading to the processing equipment can be regulated by controlling the speed of the rotor.
The invention is characterized by a highly effective and not overly expensive sealing arrangement between stationary component surfaces including valve housing surfaces, and the adjacent moving rotor surfaces. Specifically, the rotor is provided with a peripheral shroud positioned at each end of the housing chamber and the outer surfaces of these shrouds move immediately adjacent to stationary inner surfaces of openings in the housing side walls which are provided for receiving the rotor. The shroud outer surfaces are hard coated. A lip seal (or combination thereof) is mounted on each of the adjacent stationary end plate cavities to provide a barrier against movement of material and gas past this point.
A circular end plate is mounted on each side wall of the housing and each end plate defines a central opening for receiving respective smaller diameter outer sections- of the rotor shaft. Outer shaft surfaces which move adjacent the end plate surfaces are ground and hard coated and second lip seals (or combination thereof) are mounted on the end plate for engagement with these surfaces.
At each end of the housing, cavities are defined between the peripheral shrouds and the end plates with the respective lip seals closing off the ends of each cavity. A source of pressurized gas is connected to each end plate for communication with the respective cavities with this pressurized gas supplementing the ability of the lip seals to prevent intrusion of the conveying gases and material.
An arrangement of angular bearings is installed to provide significant additional sealing of the mechanism.
REFERENCES:
patent: 3151784 (1964-10-01), Tailor
patent: 4565305 (1986-01-01), Fischer et al.
patent: 4602727 (1986-07-01), Jackson
patent: 4915265 (1990-04-01), Heep et al.
patent: 4946078 (1990-08-01), Heep et al.
patent: 5201441 (1993-04-01), Hoppe et al.
patent: 5381933 (1995-01-01), Beirle et al.
patent: 5392964 (1995-02-01), Stapp et al.
patent: 5472305 (1995-12-01), Ikeda et al.
Schleicher Lawrence M.
Stark Keith W.
Chicago Conveyor Corporation
Kaufman Joseph A.
Piper Marbury Rudnick & Wolfe
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