Abstract:
A dosing device including a hopper ( 1 ) having an outlet opening which is closed by two spherical cap halves ( 3, 4 ), which can be pivoted in opposite directions. The pivoting movement is effected by two arms ( 5, 6 ) pivoted about a common pivot pin ( 8 ). The spherical cap halves ( 3, 4 ) can be pivoted by a rod assembly ( 18, 19, 22, 23 ) including a vertically mobile plunger ( 14 ). To prevent the bulk goods bridging, a rotating loosening and scraping device ( 30 ) is provided, the base ( 31 ) of which reaches close to the outlet opening. With the dosing device, both large and small quantities of bulk goods can be discharged in accurate doses.

Description:
BACKGROUND OF THE INVENTION 
     Dosing devices for tapping bulk goods from a silo-like container are already known in which an outlet opening can be opened and closed by a slide valve moving along a straight line. Depending on the type of bulk goods, difficulties may arise due to the bulk goods tending to cake or adhere to the walls of the container, thereby preventing normal flow due to bridging. It appears that, on the one hand, even if the problem of irregular follow-up flow of the bulk goods may be lessened by having a larger outlet opening, the side gap opening created by the sliding movement along a straight line, on the other hand, is unfavorable when only small quantities are required. 
     In an efficient process for filling containers, sacks and the like with bulk goods, a quantity of goods must be discharged for rough dosing at a high rate within the shortest possible time. In the case of fine dosing or tare weight packing to an accurate weight, small quantities of bulk goods must be added or removed once or several times. This creates a problem due to the fact that both a large and small through-flow opening must be available. This requirement cannot be solved satisfactorily with conventional valve closures because, with the bulk goods unfavorably responding during their flow, the weight of the material column above the narrow side gap opening is supported by the conical wall of the hopper or adheres to it so that there is an increased tendency for the bulk goods to bridge when the bulk goods are discharged in only small doses. 
     SUMMARY OF THE INVENTION 
     The purpose of this invention is to improve a dosing device for bulk goods and make it suitable for discharging small quantities of such goods as well as discharging the goods at a high through-flow rate within a wide range when large quantities of goods are to be discharged within a short time while guaranteeing faultless follow-up flow of bulk goods even with such bulk goods tending to bridge. 
     Since the closure is designed in the form of two spherical cap halves, which can be pivoted towards each other, a large through-flow opening for bulk goods is obtainable when they are pivoted away from each other into the fully open position. Alternatively, small through-flow openings can also be made, positioned in the central drop area, that is at a vertical point above the vertical material column. 
     A further advantage, in comparison with the conventional slide valve closures, consists in the fact that a more compact construction can be achieved due to the absence of the sideways slide movement overhang. This allows space-saving mounting of a number of bulk goods containers next to each other. 
     It can be useful to provide a rotatable stirring and loosening device inside the hopper when bulk materials, which flow with difficulty, and which are known to have a greater tendency to bridging are handled. Such a stirring and loosening device together with an outlet valve moving in a straight line is described in DE 256 147. As distinct from this, the rotatable stirring and loosening device can in this present case extend to the central, lower area of the outlet opening of the spherical cap halves. This reliably counteracts bridging, in the case of bulk goods which flow with difficulty, down to the lowest area of the bulk goods containers, that is down to the spherical cap halves, and guarantees the follow-up flow of the goods even when only a small through-flow aperture is open. 
     A particularly compact layout facilitating maintenance work is achieved by designing the dosing device with a bearing ring attached at the bottom to a body and a swivel ring with a driving crane located in between. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawing shows an example of design constructed in accordance with the present invention. 
     FIG. 1 is a side view of a view of a dosing device having spherical caps and parts for pivoting the spherical caps. 
     FIG. 2 is a side view with a part section through the dosing device shown in FIG. 1 with parts driving the loosening and scraping device. 
     FIG. 3 is a side view through the dosing device with the loosening and scraping device. 
     FIG. 4 is a plan view of the assembly shown in FIG. 3, in which the spherical cap halves are pivoted by a small amount to open a small through-flow aperture. 
     FIG. 5 is a section view through a version of the design. 
     FIG. 6 is a detailed view of the drive pinion. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a conical hopper  1  for bulk goods on top of which a conical or cylindrical silo-type container for bulk goods can be mounted. The hopper  1  for bulk goods is open on top and contains an outlet opening  7  at the bottom. When closed, this outlet opening is covered by two spherical cap halves  3 ,  4 . Each of the two spherical cap halves  3 ,  4  is connected to an arm  5 ,  6  that is pivoted about a common pivot pin  8  located above the outlet opening. The center line of the pivot pin  8  intersects the center vertical line  9 . The spherical cap halves are each connected firmly to the arms  5 ,  6  by means of angle brackets  10 ,  12 . 
     The two arms  5 ,  6  and thus the spherical cap halves  3 ,  4  are moved together by means of an articulated linkage. A vertical plunger  14  is intended to act together with a detachable, vertically up and down moving device which is not shown here. The plunger  14  moves in a straight line in a bearing  15 . Two rods  18 ,  19  are pivoting at the top end of this plunger  14  at a first bolt  16 . These two pivoting rods  18 ,  19  each form an acute angle with the center vertical line  9  when the spherical cap halves  3 ,  4  are in the closed position. The rods  22 ,  23  are each pivoted at the top ends of the two rods  18 ,  19  at the second bolts  20 ,  21 . The bolts  20 ,  21  pass through the arms  5 ,  6  and are connected to move together with them. These two rods  22 ,  23  are suspended at the pivot pin  8  at which the two arms  5 ,  6  also pivot. 
     A spring unit  25 ,  26  such as a gas spring or a mechanical thrust coil spring each engages at the second bolt  20 ,  21 . These spring units  25 ,  26  are biased to force the spherical cap halves  3 ,  4  into their closed position. The spring units  25 ,  26  are each suspended at a pivot  28 ,  29  on the hopper  1 . As the spherical cap halves  3 ,  4  open in response to upward movement of the plunger  14 , the length of the spring units  25 ,  26  shortens and they act as accumulators in the closing direction. 
     When closed, the two spherical cap halves  3 ,  4  can either abut against each other whilst forming a plain joint or can preferably overlap. In the case of overlapping, the center area of both spherical cap halves can have a central, arched section  33  and be designed so that a small, hole-like through opening  37  forms first during the opening movement and gradually widens as the spherical cap halves  3 ,  4  are progressively swivelled away from each other. This also allows small quantities to be discharged. 
     A rotatable loosening and scraping device  30  is located within the hopper  1 . This device is in the form of a long arm with a domed section and extends along the container wall tilted away from the axis of rotation. The lowest part  31  of this loosening and scraping unit  30 , which can be made in a single part or in several parts, extends at the bottom up to the center of the goods outlet opening and is positioned directly above the spherical bowls. Thus, as the loosening and scraping unit  30  rotates, its top part sweeps over the hopper wall and its lowest part  31  loosens the bulk material directly in front of the central outlet opening so that no bridging of the bulk material can occur even with a small outlet opening  37 . The loosening and scraping unit  30  is driven via a reduction gear unit  34  flanged at the container, its pinion engaging a ring gear  36  of a drive ring  38 . This drive ring rests in a stationary annular guide ring  40  surrounding the container  1  on the outside. The drive ring  38  is held at the guide ring  40  by several sliding shoes  42  which are equally spaced on the periphery and attached by means of bolts  44 . A radial shoulder  46  pointing inwards extends into the loosening and scraping device  30  and is driven as the drive ring  38  rotates. A ring seal  48  is fitted between the drive ring  38  and the guide ring  40 . The drive ring  38 , and preferably also the guide ring  40 , are made of a plastic with good sliding properties. 
     The reduction gear unit  34  has at the bottom an extension  35  and a detachable coupling  39  intended for detachably connecting to the opposite half of a coupling at a preferably movable motor. In place of a gear  34 , a motor drive shaft can also directly engage the ring gear  36 . 
     In one version of design, the drive for opening and closing the spherical cap halves  3 ,  4  could be operated by means of a hand crank with a screw instead of a plunger. 
     FIGS. 5 and 6 show a modified version of the dosing device. A housing type body  50  contains a hopper inner wall  52 . This body  50  is designed as a massive, thick-wall body which can be made of metal or plastic. 
     The top edge  54  of the body  50  is designed for supporting a storage hopper. A cylindrical swivel ring  55  sits at the bottom edge of the body  50 , its bore being cylindrical or slightly conical and connecting on top without a shoulder to a cylindrical bore part  59  of the body  50 . This swivel ring  55 , which is connected to the loosening and scraping unit  72 , is rotatable in relation to the body. The swivel ring  55  is surrounded by a stationary bearing ring  56  on the outside. The bore of this bearing ring  56  has several shoulders, the lowest of which overlaps the swivel ring  55 . The bearing ring  56  is immovably mounted on the body  50  by means of several bolts  70  spaced out on the periphery. The swivel ring  55  is thus held rotatably between the seals of the bearing ring  56  and the body  50 . A drive ring  60 , which is radially spaced from a bore part  58  of the bearing ring  56 , is connected with the swivel ring  55  against rotation. The drive ring  60  contains a ring gear  36  which meshes with a side pinion  63  (FIG.  6 ). The latter meshes with a drive pinion  62  provided with a shaft  69  which can be coupled with a drive (not shown). In a different design version, the drive pinion  62  could also mesh with the ring gear  36  directly or a toothed belt could be placed around the ring gear  36 . 
     The body  50  has two outside faces  64 , which are parallel to each other, on which the actuating devices  18 ,  19  for moving the spherical cap halves rest on bearings  15 . These actuating devices correspond to those described and illustrated in connection with FIGS. 1 to  4 . The parts  50 ,  55 ,  56  and  60  can be made either of metal or plastic. 
     Rotating the drive shaft  69  shall thus cause the loosening and scraping device, extending up to the spherical cap halves, to rotate, thereby preventing bridging of the bulk goods when the spherical cap halves are opened. The loosening and scraping device, which is fitted removably in the attachment device  61 , runs in the upper section parallel to the hopper wall  52  and extends below into the hole  75  and down to the central area of the spherical cap halves. In addition, the loosening and scraping device  72  is tilted backwards in the upper area in relation to the direction of rotation.