Patent Publication Number: US-2002005416-A1

Title: Cellular-wheel sluice with fast-changeable sealing arrangement

Description:
FIELD OF THE INVENTION  
       [0001] The invention relates to a cellular-wheel sluice of the type defined by the preamble to claim  1 . Cellular-wheel sluices of this type are used to feed bulk material into pneumatic feeding systems, in particular plastic granulate in dense-phase feeding systems, with feed pressures up to delta p which is equal to or less than 3 bar of overpressure.  
       BACKGROUND OF THE INVENTION  
       [0002] As a characteristic feature, they have closed cellular wheels, that is, laterally disposed side disks on the cellular-wheel struts, into which a radially or axially acting sealing arrangement is integrated.  
       [0003] To relieve the seal from sagging forces, for reasons of lengthening its service life, considerable efforts have been undertaken.  
       [0004] German Patent DE 40 19 628 C2 describes a version in which the sealing arrangement follows along with the bending motion of the cellular wheel, since the parts that together with the side disks of the cellular wheel form the sealing arrangement are rotatably supported on the shaft.  
       [0005] To an increasing extent, these cellular-wheel sluices are also being employed for abrasive products. This means that the sealing rings have to be changed at shorter intervals.  
       [0006] If so-called fast-cleaning versions are used in DE 40 196 28 for opening the sluice and removing the cellular wheel, then the two sealing arrangements remain in the assembled state. Not until the system is completely dismantled is it possible to gain access to the radial sealing rings. This is time-consuming and therefore can be done only after removing the cellular-wheel sluice on site and then transporting the remainder to a repair facility.  
       OBJECT AND SUMMARY OF THE INVENTION  
       [0007] The object of the invention is to gain immediate access on site to the radial sealing ring, making its replacement a matter of minutes and so that the system can be maintained to prevent seal failure along the lines of the DIN standard 31051 on upkeep and kept ready for operation.  
       [0008] This object is attained by the characteristics of the body of claim  1 .  
       [0009] An essential characteristic of the present invention is that now a cellular-wheel sluice is embodied with one side cap on the left and another on the right; the bearing arrangement for the cellular-wheel shaft is disposed in each side cap, and a side disk split into at least two parts is disposed in each side cap; the inner side disk is oriented toward the cellular wheel, and the other side disk is toward the respective side cap, and the radial sealing arrangement is disposed between the two side disks.  
       [0010] This has the essential advantage that this radial sealing arrangement is now especially easily accessible and thus is also embodied as easy to release. All that is now needed is to remove the respective side cap; together with the side cap, according to the invention, the side disk associated with the side cap is removed, because this side disk is connected to the side cap.  
       [0011] Now that the radial sealing arrangement is disposed in a space between the inner and outer side disks, this radial sealing arrangement is now especially easily accessible.  
       [0012] It does not matter, and both possibilities are covered by the scope of the present invention, whether the radial sealing arrangement remains on the inner side disk and is correspondingly easily accessible, or the radial sealing arrangement is oriented toward the outer side disk and can be moved together with the outer side disk and the side cap.  
       [0013] The nucleus of the invention is accordingly that the cellular wheel has at least two splittable side disks, which separate after being opened; the side disks that remain on the cellular wheel are supported via the shaft in the side cap, and the side disks that remain in the side cap are rotatably supported on their own hub, after the separation, the sealing ring is free on both sides for inspection and possible replacement.  
       [0014] In initial assembly, the separated side disks join together to form two units that rotate in common, and on the circumference they form the cavern for the sealing ring unit.  
       [0015] The bending compensation is assured since the theoretical center points shift toward one another during rotation on the common sealing O-rings.  
       [0016] This is understood to mean that the cellular-wheel shaft bends under stress. As a result, corresponding bending forces are also introduced to the radial sealing arrangement. By splitting the side disks into two parts, it is now attained that the inner side disk is always firmly joined to the cellular-wheel strut, and correspondingly goes along with the deforming work of the cellular wheel, while the outer side disk is joined to the side cap and correspondingly remains in position. Accordingly, the two side disks execute a certain displacement motion in the radial direction relative to one another, for instance by a distance of two-tenths of a millimeter.  
       [0017] It is preferred if this radial sealing arrangement comprises a multiple-part sealing ring, with which still other radial sealing rings are associated, namely preferably one further O-ring and a support ring belonging to it, these further rings being disposed at various radial spacings from the cellular-wheel shaft.  
       [0018] This entire sealing arrangement accordingly executes the above-described play of motion, and as a result adequate sealing is assured at all times under all loading states.  
       [0019] It is understood that the present invention is not limited to this type of seals as described; a stuffing box (packing ring) or a lip seal ring or other suitable kinds of seals may also be used. What is definitive is only the splitting of the side disk into at least one inner and one outer side disk, with the appropriate sealing arrangement disposed between the two side disks. This accordingly has the advantage—as noted above—that when the cap is removed, the outer side disk is removed along with the cap, and as a result the sealing arrangement disposed between the two side disks is then freely accessible and easy to replace.  
       [0020] The invention will now be described in further detail in conjunction with the drawings, which show merely one possible embodiment. Other characteristics essential to the invention and advantages of the invention will become apparent from the drawings and their description.  
       [0021] The subject of the present invention encompasses not merely the subject of the individual claims but also the combination of the individual claims with one another.  
       [0022] All the statements in specifications disclosed in the present text, including the abstract, and in particular the three-dimensional embodiment shown in the drawings, are claimed as essential to the invention to the extent that individually or in combination with one another they are novel over the prior art. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0023]FIG. 1 is a section through the fixed bearing side of a cellular-wheel sluice according to the invention; and  
     [0024]FIG. 2 is a section through the drive bearing side of the same cellular-wheel sluice, showing it after the side cap has been partly removed.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0025] In FIGS. 1 and 2, the left and right sides of a cellular-wheel sluice are shown; in FIG. 2, not all the parts are designated because they have already been shown in FIG. 1 and described accordingly in the ensuing description.  
     [0026] In a manner known per se, a number of cellular-wheel struts  2 ,  3  are disposed on a cellular-wheel shaft  1  in a manner fixed against relative rotation; in combination with associated housing edges, they form a sealing gap  9 . One housing flange  6  for an inlet  4  is disposed on top of the housing of the cellular-wheel sluice, and a further housing flange  6  for an outlet  5  is disposed on the underside.  
     [0027] An important feature is that an inner side disk  7  is connected via welded points  8  or other fastening means directly to the revolving part of the cellular-wheel sluice, such as the cellular-wheel shaft  1  or the cellular-wheel struts  2 . Accordingly, the side disk  7  revolves with the cellular wheel.  
     [0028] By comparison, a side disk  13  rotatably supported on the side cap  21 , in combination with the inner side disk  7 , defines a radial sealing arrangement. This radial sealing arrangement comprises an outer multiple-part sealing ring  10 , which preferably is a combination of one PTFE-compound ring, one O-ring and one metal support ring, an O-ring  11  located radially under it, and a further O-ring  12  located radially under O-ring  11 .  
     [0029] The bearing of the outer side disk  13  is accomplished in such a way that it has an axial collar, on which a groove for receiving a bearing  16  is milled. This bearing  16  is axially prestressed by an axial ring  20  and a cup spring  19 ; the cup spring  19  is supported on one side on the ring  20  and on the other on a radial collar of a hub  17 , which on the one hand carries the bearing  16  and on the other is secured by means of screws  18  to the side cap  21 . The internal diameter of cup or disk spring  19  touches ring  20  and the external diameter touches disk  17 , connected to side cap  21 .  
     [0030] A conduit  22  extends through the side cap  21  as far as the interior of an inner hollow chamber  14  that is used for ventilation. The side cap  21  is releaseably secured to the housing flange  6  by means of screws  23  that are distributed uniformly on the circumference.  
     [0031] The side cap  21  also has an outer guard cap  24 , which is secured to it by screws  25 . The guard cap  24  supports the two support bearings  26 , which are disposed between the side cap  21  and an associated collar  30  of the cellular-wheel shaft  1 , and which are the main bearings which have to take the force of the conveying pressure against the star-valve.  
     [0032] The two support bearings  26  are axially prestressed by a screw  27  and an associated disk  28 .  
     [0033]FIG. 2 shows the easy accessibility of the radial sealing arrangement  10 ,  11 ,  12 . That is, if the screws  23  are undone, the entire side cap  21  can then be pulled off in the axial direction, in terms of FIG. 2, and removed from the collar  30  of the cellular-wheel shaft  1 , thereby producing a relatively large free space  29 , into which one can gain access in the direction of the arrow  31  to the seals  10 ,  11 ,  12  and easily replace them.  
     [0034] It is understood that the invention is not limited to this sealing arrangement  10 ,  11 ,  12 ; it may also be embodied differently.  
     [0035] It is equally possible for the entire sealing arrangement  10 ,  11 ,  12  to be disposed in the region on the inside of the side disk  7 .