Discharge means for a silo

Abstract: A discharge means for a silo comprising an entry chamber (20) adapted to be in communication with the silo interior (11) and having a directing member (33) mounted in the entry chamber (20), for rotary movement about a vertical axis (22), to direct flowable material in the entry chamber (20) through a discharge passage in a bottom wall (19) of the chamber.

Description: This invention relates to a discharge means for a storage container for flowable material such as freely flowable such as powder or granular material, for example grain, or material of restrictive flowability or cohesive material, for example cement, damp sand, sludges, coagulative, or fibrous materials or the like, hereinafter referred to as a silo. Hitherto a silo has been provided with a downwardly converging discharge portion which defines an entry chamber in communication with the silo interior and having a generally cone-shaped obstructing member disposed therein to define a ring-shaped discharge passage between the base of the cone shaped member and the converging discharge portion and means being provided to vibrate or otherwise agitate the discharge portion and/or the cone-shaped member to facilitate discharge flow of material through the ring-shaped passage. Such discharge means suffer from the disadvantage that bridging of the material may occur or, alternatively, material may flow from the centre only, inducing core flow, and either of these disadvantages can lead to inconsistencies in the discharge. The use of a rotating arm to direct the flowable material in a path having a radially inward component towards a discharge passage adjacent the axis of rotation of the arm is also known, for example from DE-A-3503993. Such an arrangement suffers the disadvantage that it may permit material to enter the discharge passage even when the arm is not rotating. An object of the invention is to provide a new and improved discharge means in or for a silo overcoming the aforementioned disadvantages. According to the invention we provide a discharge means for a silo comprising an entry chamber adapted to be in communication with the silo interior and having a directing member mounted in the entry chamber, for rotary movement about a vertical axis, to direct flowable material in the entry chamber through a discharge passage in a bottom wall of the chamber, the directing member comprising at least one arm having an outer end which projects radially further from the axis of rotation of the directing member than does an inner part whereby on rotation of the directing member the arm is adapted to engage flowable material in the chamber and direct the flowable material in a path which has a radially inward component towards the discharge passage in the bottom wall, characterised in that the directing member has a generally upwardly extending wall having at least one opening therein associated with the or each arm so that the flowable material is directed by the associated arm through the or each associated opening, and the or each opening in the upwardly extending wall of the directing member is provided with a closure member so as to control discharge through the or each opening. The discharge passage may be adjacent the axis of rotation of the directing member and may partially surround the axis. The upwardly extending wall may be disposed adjacent to the bottom wall and radially outwardly of the periphery of the discharge passage so as to prevent flowable material entering the discharge passage except through the or each opening in said upwardly extending wall. Preferably the or each arm comprises an upwardly extending wall and the or each arm may have a transversely extending portion extending between the upwardly extending wall of the directing member and the arm. The directing member may include an obstructing portion to prevent passage of flowable material from the chamber through the discharge passage from above. The or each closure member may be mounted for rotation relative to the directing member so as to be movable from a position in which the or each closure member obstructs and so closes an associated opening and a position in which the or each closure member is disposed inwardly of the upwardly extending wall and circumferentially out of alignment with the opening to permit passage of material therethrough. The or each closure member may be mounted on a mounting means mounted for rotation about the axis of rotation of the directing member, and the directing member may be provided with stop means to limit relative rotation between the or at least one of the closure members and the directing member. Drive means may be provided whereby the mounting means drives the or each closure member about said axis of rotation into engagement with said stop means then to drive the directing member, as a result of said engagement, about said axis of rotation. The stop means may be positioned so that the closure member or members are not in closing relationship with the openings when in said driving engagement with said stop means. Rotation of the mounting means in the reverse direction causes relative rotation between the or each closure member and the directing member to bring the closure members into closing relationship with an associated aperture or apertures as a result of the directing member remaining stationary during such reverse relative movement. The mounting means may be adapted to be non-rotatably connected to a driveshaft which is rotatable about said axis of rotation, and said drive means may be carried by said bottom wall of the chamber and the closure member and thus the directing member may be driven by a transversely extending drive shaft drivably engaged with said drive means. Two examples of the invention will be described with reference to the accompanying drawings wherein:- Figure 1 is a side elevation of a silo embodying the invention, Figure 2 is a fragmentary perspective view with parts omitted, and to an enlarged scale, of the discharge means of the silo of Figure 1, and Figure 3 is a fragmentary perspective view with parts omitted of an alternative discharge means. Referring to Figures 1 and 2, a silo for flowable or cohesive material such as grain, cement, damp sand, sludges, coagulative, fibrous materials or the like is indicated generally at 10 in Figure 1 and comprises a main container part 11 of generally cylindrical configuration supported on a leg structure 12 with cross-braces 13. At the lower end of the generally cylindrical main container part 11 is a frusto-conical discharge portion 14 having at its lower end an outwardly extending annular flange 15 to which is bolted an outwardly extending annular flange 16 of an exit portion 17 of a discharge means 18. The discharge portion 14 together with an annular plate 19 clamped between the flanges 15 and 16 defines an entry chamber 20 which is in communication with the main interior 11 of the silo 10 and of which the plate 19 provides a bottom wall. The plate 19 has a central circular aperture 21 which provides a discharge passage from the chamber 20. Disposed centrally within the discharge passage 21 is an shaft 22 provided with a bevel gear, not shown, at its lower end in a gearbox 23 carried by tubular struts 24 welded to the exit portion 17. Also provided within a gearbox housing 23 for meshing engagement with the bevel gear on the shaft 22 is a further bevel gear which is rotatably connected to a drive input shaft 25 rotatably mounted within one of the three struts 24 and adapted to be rotated by a drive motor, not shown. Keyed to the shaft 22 by a key 26 is a mounting member 27 connected to a spider 28 having four arms 29 which at their outer ends carry part cylindrical closure members 30. At its upper end the shaft 22 has the upper end 31 of a generally frusto-conical obstructing member portion 32 of a directing member 33 rotatably mounted thereon. The directing member 33 has, at the lower, larger diameter, end of the frusto-conical part 32 a generally cylindrical wall 34 which rests on the plate 19 adjacent to and spaced outwardly of the aperture 21 therein and extending upwardly relative thereto. The wall 34 is provided with four generally rectangular apertures 35 and adjacent the one ends of each aperture 35 is provided a stop element 36 which projects radially inwardly. Associated with each aperture 35 is a directing arm 40 having an outer free end 41 which is spaced radially further from the axis 22 than the radially inner end 42 thereof. Each arm 40 has an inner part 43 of generally rectilinear generally chordal configuration and an outer part 44 connected thereto by a curved portion. The arm 40 is connected, at its upper end, to the upper end of the generally cylindrical wall 34 by a closure plate 45. In use, when it is desired to discharge material from the main body 11 of the silo 10, the input drive shaft 25 is driven to rotate the shaft 22 in a clockwise direction as shown in Figure 2. When the shaft 22 is rotated clockwise the key 26 causes the spider 28 to rotate to cause the closure member to engage the abutments 36 thus initially to move the closure members 30 out of closing relationship with the apertures 35 and then, when they engage the abutments 36, into driving engagement with the directing member 33 to cause it to rotate clockwise. As a result, the flowable material within the input chamber 20 is directed by the generally funnel shaped configuration provided by the walls 40, 45 and 19, into and through the apertures 35 and then due to gravity through the spaces between the arms 28 and through the discharge aperture 21. When it is desired to stop the flow of flowable material the direction of rotation of the input drive is reversed so that the shaft 22 is rotated in an anti-clockwise direction in Figure 2 and this causes the closure members 30 to rotate anti-clockwise relative to the directing member to cause the closure members 30 to obturate and so close the openings 35 to prevent any flow of flowable material therethrough. Referring now to Figure 3, in which the same reference numerals have been used to refer to corresponding parts as were used in Figure 2. Figure 3 shows an alternative discharge means which is essentially similar to that illustrated in Figures 1 and 2, but in which the plate 19, instead of having a central circular aperture 21, has three symmetrically disposed part annular apertures 21 a so that the plate has three radial arms 21 b between the apertures and a central, generally circular hub part 21 c . Mounted below the hub part 21 c is a gearbox 23 in which an shaft 22 is rotatably mounted by means of thrust and journal bearings, not shown. The lower end of the shaft 22 has a bevel gear, not shown, for meshing engagement with a further bevel gear, not shown, within the gearbox, which is rotatably connected to a drive input shaft 25 which extends radially relative to the axis of rotation of the shaft 22 within a tube 25 a that extends through an aperture in the wall of the exit portion 17 and has a flange 25 b on which a bearing, not shown, for the outer end of the shaft 25, can be mounted. At its outer end the shaft 25 has a splined portion 25 c for connection to a drive motor. A flexible tubular cover is provided between the tube 25 a and the gearbox 23 to allow for any misalignment of the tube 25 a with the gearbox 23. Keyed to the shaft 22 by a key, not shown, is a mounting member 27 connected to a spider 28 having two arms 29 which at their outer ends carry part cylindrical closure members 30. At its upper end the shaft 22 has the upper end 31 of a generally frusto-conical obstructing member portion 32 of a directing member 33 rotatably mounted thereon. The directing member 33 has, at the lower, larger diameter, end of the frusto-conical part 32 a generally cylindrical wall 34 which rests on the plate 19 adjacent to and spaced outwardly of the apertures 21 a therein and extending upwardly relative thereto. The wall 34 is provided with two generally rectangular apertures 35 and adjacent the one ends of each aperture 35 is provided a stop element 36 which projects radially inwardly. Associated with each aperture 35 is a directing arm 40 having an outer free end 41 which is spaced radially further from the axis 22 than the radially inner end 42 thereof. Each arm 41 is of curved configuration. The wall 41 is connected, at its upper end, to the upper end of the generally cylindrical wall 34 by a closure plate 45. In use, when it is desired to discharge material from the main body 11 of the silo 10, the input drive shaft 25 is driven to rotate the shaft 22 in a clockwise direction as shown in Figure 3. When the shaft 22 is rotated clockwise the key 26 causes the spider 28 to rotate to cause the closure member to engage the abutments 36 thus initially to move the closure members 30 out of closing relationship with the apertures 35 and then, when they engage the abutments 36, into driving engagement with the directing member 33 to cause it to rotate clockwise. As a result, the flowable material within the input chamber 20 is directed by the generally funnel shaped configuration provided by the walls 40, 45 and 19, into and through the apertures 35 and then due to gravity through the spaces between the arms 28 and through the discharge apertures 21 a . When it is desired to stop the flow of flowable material the direction of rotation of the input drive is reversed so that the shaft 22 is rotated in an anti-clockwise direction in Figure 2 and this causes the closure members 30 to rotate anti-clockwise relative to the directing member to cause the closure members 30 to obturate and so close the openings 35 to prevent any flow of flowable material therethrough.

Claims: A discharge means in or for a silo (10) comprising an entry chamber (20) adapted to be in communication with the silo interior (11) and having a directing member (33) mounted in the entry chamber (20), for rotary movement about a vertical axis, to direct flowable material in the entry chamber through a discharge passage (21) in a bottom wall (19) of the chamber (20), the directing member (33) comprising at least one arm (40) having an outer part (44) which projects radially further from the axis of rotation of the directing member (33) than does an inner part (43) whereby on rotation of the directing member (33) the arm (40) is adapted to engage flowable material in the chamber and direct the flowable material in a path which has a radially inward component towards the discharge passage (21) in the bottom wall (19) characterised in that, the directing member (33) has a generally upwardly extending wall (34) having at least one opening (35) therein associated with the or each arm (40) so that the flowable material is directed by the associated arm (40) through the or each associated opening (35), and the or each opening (35) in the upwardly extending wall (34) of the directing member (33) is provided with a closure member (30) so as to control discharge through the or each opening (35). A discharge means according to claim 1 wherein the discharge passage (21) is adjacent the axis of rotation of the directing member (33) and at least partially surrounds the axis. A discharge means according to claim 1 or claim 2 wherein the upwardly extending wall (34) is disposed adjacent to the bottom wall (19) and radially outwardly of the periphery of the discharge passage (21) so as to prevent flowable material entering the discharge passage (21) except through the or each opening (35) in said upwardly extending wall (34). A discharge means according to any one of the preceding claims wherein the or each arm (40) comprises an upwardly extending wall (44) and the or each arm has a transversely extending portion (45) extending between the upwardly extending wall (34) of the directing member and the arm (40). A discharge means according to any one of the preceding claims wherein the directing member (33) includes an obstructing portion (32) to prevent passage of flowable material from the chamber (20) through the discharge passage (21) from above. A discharge means according to any one of the preceding claims wherein the or each closure member (30) is mounted for rotation relative to the directing member (33) so as to be movable from a position in which the or each closure member (30) obstructs and so closes an associated opening (35) and a position in which the or each closure member (30) is disposed inwardly of the upwardly extending wall and circumferentially out of alignment with the opening (35) to permit passage of material therethrough. A discharge means according to claim 6 wherein the or each closure member (30) is mounted on a mounting means (27) mounted for rotation about the axis of rotation of the directing member (33) and the directing member (31) is provided with stop means to limit relative rotation between the or at least one of the closure members (30) and the directing member (33). A discharge means according to claim 7 wherein drive means are provided whereby the mounting means (27) drives the or each closure member (30) about said axis of rotation into engagement with said stop means (36) then to drive the directing member (33), as a result of said engagement, about said axis of rotation. A discharge means according to claim 8 wherein the stop means (36) are positioned so that the closure member or members (30) are not in closing relationship with the openings (35) when in said driving engagement with said stop means. A discharge means according to claim 9 wherein the mounting means (27) is adapted to be non-rotatably connected to a driveshaft (22) which is rotatable about said axis of rotation and said drive means is carried by said bottom wall (11) of the chamber and the mounting means (27) is driven by a transversely extending drive shaft (25) drivably engaged with said drive means.

Inventors: PETHULLIS JOHN KEVIN, PETHULLIS, JOHN KEVIN
Applicants: PORTASILO LTD, PORTASILO LIMITED
Application year: 1995
Main classification: B65D88
IPC codes: B65G65