Abstract:
A venturi incorporated in a pneumatic tube conveying system for flexible textile fabrics such as uniform and table linens handled in commercial laundries. The venturi includes an angled pipe which joins the main piping system at an acute angle and which receives air from a blower. An inside pipe is installed within the main piping to create a restriction at the connection of the venturi with the main piping. The restriction and angled connection of the venturi pipe creates a low pressure area which draws fabric articles through the piping and discharges them directly into receptacles such as sling carts. A screened vent in the piping downstream from the venturi allows the escape of air to enhance the reliability and efficiency of the pneumatic conveying system. The exposure of the vent can be adjusted by a sleeve that slides back and forth on the conveyor tube at the location of the vent.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to the pneumatic conveying of flexible fabrics such as uniforms, table linens and other articles handled by commercial laundries, as well as other fabric items that are conveyed between different locations in other types of applications. More particularly, the invention is directed to a method and apparatus that makes use of a specially constructed venturi to provide a suction force for pulling fabrics through conveyor tubes. 
     BACKGROUND OF THE INVENTION 
     Commercial laundries handle large volumes of a variety of materials, including table cloths, napkins and other table linens used in restaurants and other food service operations. Uniforms worn by fast food service personnel and others are examples of other types of articles that are typically laundered by commercial laundries. A significant part of the operation of commercial laundries involves sorting the different types of articles while keeping track of where they came from and the number and types of articles that are to be laundered. 
     Typically, the items are sorted at a sorting table or other sorting station. Like articles are then conveyed pneumatically to another location where they are further handled. Because flexible fabrics tend to ball up when pushed through pneumatic conveyor tubes, they are usually pulled through the tubing system by suction. The type of system that is most prevalent in commercial laundries makes use of vacuum bins that are each provided with a large vacuum motor. The vacuum that is applied to the vacuum bins pulls the laundry items through the conveyor tubes and into the bins. 
     Although vacuum bins of this type have achieved considerable popularity, they have not been satisfactory in all respects. Their relatively high cost adds appreciably to the capital costs of the laundry equipment. Furthermore, it is necessary for the items in the vacuum bins to be manually unloaded and placed on a conveyor which carries them to the location of receptacles that are typically flexible carts commonly referred to as sling carts. The articles must then be manually unloaded from the conveyor and placed in the sling carts. As can easily be appreciated, the need for all of these manual operations adds significantly to the overall labor costs. Finally, the vacuum bins and conveyors that transport articles from the bins to the sling carts occupy considerable space. This is particularly unsatisfactory in the case of commercial laundries because they are usually located in high cost urban areas where they are close to their major customers. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a method and apparatus for conveying flexible fabric articles in an improved way that avoids the shortcomings of vacuum bin systems. In particular, the present invention provides a venturi system that dramatically reduces the equipment costs, labor costs and space requirements compared to vacuum bin systems. 
     In accordance with the invention, a uniquely arranged venturi structure is provided for applying a suction force at a selected location along the conveyor tube system rather than at its discharge end as is necessary with a vacuum bin system. Because the venturi is located along the conveyor tubing, the tubing can discharge the fabric items directly into sling carts or other receptacles, thus eliminating the space occupied by the vacuum bins and the intermediate conveying system as well as the labor that is required to manually unload the articles from the vacuum bins and to later load them into the sling carts. 
     The venturi system of the present invention preferably includes an angled pipe which joins the conveyor tubing at an acute angle and is supplied with air by a blower. An inside pipe is located within the tubing at its juncture with the angled venturi pipe in order to provide a restriction that creates a low pressure area in the conveyor tubing. The resulting suction force draws the fabric articles to the area of the venturi and thereafter transports them a relatively short distance to the discharge end of the conveyor tubing by the positive force supplied by the blower. At the discharge end of the tubing, the fabric articles are discharged directly into receptacles such as sling carts. 
     An important feature of the invention is the provision of a vent in the conveyor tubing at a location downstream from the venturi. The vent is preferably a screened gap in the tubing which allows a portion of the air to escape. The vent significantly enhances the smoothness and reliability of the conveyor system by partially relieving the air pressure and thereby suppressing pressure fluctuations and other unfavorable pressure conditions that can adversely affect operation of the conveyor system. An adjustable sleeve in the preferred embodiment of the invention allows the width of the gap to be adjusted as necessary. 
     Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views: 
     FIG. 1 is a diagrammatic view of a pneumatic conveyor tubing system that is equipped with a venturi arrangement constructed according to a preferred embodiment of the present invention and used to convey flexible fabrics from a sorting table or other sorting station to receptacles such as sling carts; and 
     FIG. 2 is a fragmentary sectional view on an enlarged scale showing the venturi system and the adjacent portions of the conveyor tubing. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a method and apparatus for the pneumatic conveying of fabric materials such as table linens (table cloths, napkins and the like), uniforms, and other articles that are typically laundered in commercial laundries, as well as other flexible fabrics that are pneumatically conveyed in other applications. FIG. 1 illustrates diagrammatically a pneumatic conveying system of the type that may be installed in a commercial laundry facility. A sorting table generally identified by numeral  10  or a similar sorting station is used for the sorting of articles and may be equipped with a back panel  12  having a transparent window  14 . Pneumatic conveyor tubing generally identified by numeral  16  extends from the back of the table and is located for the most part at an overhead location, although other locations are possible. 
     An opening  18  in the panel  12  may provide an input opening into which articles may be fed into a vertical tube  20  which is part of the conveyor tubing  16 . An elbow  22  connects the top end of tube  20  with an elevated horizontal conduit  24  which terminates in a substantially straight end portion  26 . The conduit  24  may have virtually any desired configuration and can include bends and other offsets as may be necessary to avoid obstructions or extend the conveyor tubing to the desired location. The conduit  24  may incorporate a number of separate tube sections suitably coupled together. 
     The end portion  26  of conduit  24  is connected by a coupling  28  with a conduit section  30  which has a substantially straight main body and a branch leg  32 . The leg  32  has an axis that is oriented at an acute angle to the longitudinal axis of conduit section  30 . 
     The downstream end of conduit section  30  is connected with another conduit  34 . A vent opening between conduits  30  and  34  is provided, preferably by a gap  36  that is covered with a mesh screen  38 . The ends of conduits  30  and  34  are spaced apart so that the gap  36  extends circumferentially around the conveyor tubing. The screen  38  covers the entirety of the gap  36  to prevent articles that are being conveyed from passing out of the conveyor tubing  16  through the gap. A solid sleeve  39  is fitted closely around the downstream end of conduit section  30  and is adjustable in a manner to wholly or partially cover the screen  38  or to not cover the screen at all. The sleeve  39  slides back and forth in order to vary the size of the gap  36  and thus vary its exposure. 
     The downstream end of conduit  34  is provided with a plurality of serially arranged fittings  40 ,  42  and  44 . Each fitting  40 ,  42  and  44  has a discharge opening  46  which is controlled by a flapper valve  48  or other device. The openings  46  may be located and oriented as desired. The valves  48  are controlled by a suitable control system (not shown) which is not a part of the present invention. Immediately underlying the discharge openings  46  are respective receptacles  50  which may take the form of sling carts or other types of receptacles or other devices such as belt conveyors that receive the fabric articles that discharge through the openings  36  of the fittings  40 ,  42  and  44 . 
     The branch leg  32  forms part of a venturi arrangement constructed according to a preferred embodiment of the present invention. A blower  52  which may be mounted on the floor or elsewhere is powered by a motor  54  and forces air from the discharge side of the blower through piping that includes an inclined or angled pipe  56  leading to connection with the branch leg  32 . 
     With reference to FIG. 2 in particular, an inside pipe  58  is suitably supported concentrically inside of the conduit section  30  and is positioned to overlie the inlet opening  60  formed at the intersection of the branch leg  32  with the main body of conduit  30 . The inside pipe  58  is smaller in diameter than the main body of conduit  30  to provide a restriction  62  adjacent to the downstream end  64  of the inside pipe  58 . The restriction  62  is annular and creates a reduced volume region adjacent to the end  64  in order to provide a low pressure in the conduit section  30  at the area of the downstream end  64  of the inside pipe  58 . The end  64  is spaced downstream from the opening  60  by a distance identified by numeral  66  in FIG.  2 . By way of example, the conduit end portion  26  may be a six inch diameter pipe, with the main body of conduit section  30  being an eight inch diameter pipe. The inside pipe  58  preferably has approximately the same diameter as the end portion  26 , or six inches in the case where the conduit end portion  26  is a six inch pipe. With these dimensions, the distance  66  is preferably about three inches, although the distance can vary considerably. 
     The inside pipe  58  has an upstream end  68  which is spaced downstream from the conduit end portion  26  by a distance identified by numeral  70  in FIG.  2 . With the pipe sizes given previously by way of example, the distance  70  may be approximately six to seven inches, although this dimension can also vary considerably without adversely affecting the operation of the system. Both ends of the inside pipe  58  are open so that the fabric articles that are being conveyed through the tubing  16  can pass through pipe section  58 . With the pipe sizes given, the length of the inside pipe  58  may be about 24 inches, although variations are possible. 
     The screen  36  is preferably cylindrical and is fitted over the downstream end of conduit section  30  and secured thereon by a band type pipe strap  72  or other suitable means. The screen  38  is fitted around the upstream end of conduit  34  and secured by a band type strap  74  or another suitable means. Connecting screen  38  in this fashion connects conduits  30  and  34  to one another. The distance between the downstream end  64  of the inside pipe  58  and the gap  36  is preferably no less than 10 inches and can be considerably greater. The length of the gap  36  between the ends of the conduits  30  and  34  may be approximately six inches, although the length of the gap can vary considerably depending upon a number of factors, including the sizes of the pipes and blower and the location of the gap relative to the venturi. The width of the gap  36  can also be adjusted by sliding the sleeve  39  to control its exposure. 
     In operation, the blower  52  operates to force air through the inclined pipe  58  and the branch leg  32  into conduit  30  at the restriction  62 . The abrupt change in volume provided by the restriction  62  creates a low pressure area adjacent to the downstream end  64  of the inside pipe  58 . Fabric articles that are loaded into the conveyor tubing  16  are drawn through the conduits  20  and  24  and into the conduit section  30  by the suction resulting from the low pressure area, and the articles are drawn through the inside pipe  58 . Downstream from the venturi, the articles are conveyed to the discharge fittings  40 ,  42  and  44  by the positive force of the air supplied by the blower  52 . 
     The flapper valves  48  are suitably controlled to open a selected one of the valves  48 , such as the valve of fitting  42  as shown in FIG.  1 . The articles are then deflected by the flapper valve  48  through the discharge opening  46  and into the underlying receptacle  50  identified as receptacle # 2  in FIG.  1 . Different articles are similarly deposited into the other receptacles  50  by opening the flapper valve  48  associated with the corresponding fitting  40  or  44 . It should be understood that virtually any desired number of discharge fittings can be provided and that other types of discharge systems can be used in connection with the pneumatic conveying system. 
     The vent effect provided by the gap  36  is an important feature of the invention because it allows a portion of the air supplied by the blower  52  to escape from the conveyor tubing  16 . The escape of some of the air avoids significant pressure fluctuations and other unfavorable pressure conditions in the tubing  16 , thereby enhancing the reliability of the conveying system and assuring that it operates smoothly. 
     The suction effect created by the venturi of the present invention is applied at a selected location along the conveyor tubing  16  rather than at the discharge end of the tubing as is necessary with a vacuum bin system. Consequently, the fabric articles that are being conveyed can be deposited directly into the receptacles  50 , rather than having to be removed from a vacuum bin and separately conveyed to the location of the receptacles  50  where an additional manual operation of depositing the articles in the receptacles  50  is required. Thus, the venturi system of the present invention is a substantial improvement over a vacuum bin system in a number of respects, namely, the elimination of the high cost of the vacuum bins and the large vacuum motors they require, a reduction in the labor that is required, and a reduction in the amount of space occupied by the equipment. 
     From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.