Backflushable filtering apparatus for molten material and distribution unit for a filter device of this type

Abstract

A backflushable filtering apparatus for a molten material, particularly for a plastic melt, comprises a housing ( 1 ) in which a sieving arrangement ( 17 ) is provided which includes at least two sieving sections ( 16 ) separated from one another. The melt to be filtered is supplied to the sieving sections ( 16 ) through at least one distributor ( 3 ). The distributor ( 3 ) includes at least one control body ( 9 ) for backflushing which is moveable within a housing ( 53 ) that is provided with an inlet opening ( 4 ) for the material to be filtered. The control body ( 9 ), in a filtering position, unblocks the influx of material to be filtered to all sieving sections ( 16 ) through connection channels ( 23 ). However, in a backflushing position, the control body ( 9 ) interrupts the influx of material to the filtering section ( 16 ) to be backflushed and interconnects the connection channel ( 23 ) of the sieving section ( 16 ) flushed back with a discharge channel ( 28 ) located in the control body ( 9 ). At least the majority of the circumference of the control body ( 9 ) is surrounded by a distribution space ( 7 ) for the material to be filtered which is situated within its housing ( 53 ). The distribution space ( 7 ) is connectable through the connection channels ( 23 ) to all sieving sections ( 16 ) in communication with the distributor ( 3 ). Guiding channels ( 6 ) lead from the inlet opening ( 4 ) to the regions of the two front ends ( 61, 62 ) of the distribution space ( 7 ). These front ends ( 61, 62 ) are situated in the region of the outermost connection channels ( 23 ) or outside the region of all connection channels ( 23 ). The discharge channel ( 28 ), which leads away from the control body ( 9 ), may be caused to communicate with the connection channel ( 23 ) of the respective sieving section ( 16 ) to be flushed back through a flush back channel ( 27 ) of at least one cross-piece ( 14 ) of the control body ( 9 ) which overbridges the distribution space ( 7 ).

1 - 21 . (canceled)  
   
   
       22 : Distributor for a backflushable filtering apparatus, comprising a housing ( 53 ) and a control body ( 9 ) for backflushing moveable therein, to which the material to be filtered is supplied through an inlet opening ( 4 ) and which, in filtering position, unblocks the influx of this material to at least two connection channels ( 23 ) which may be interconnected to sieving section ( 16 ) of the filtering apparatus, whereas in a flush back position, the control body ( 9 ) interconnects one of these connection channels ( 23 ) with a discharge channel ( 28 ) situated in the control body ( 9 ), the inlet opening ( 4 ) communicating with a distribution space ( 7 ) arranged in the housing ( 53 ) and whose majority surrounds the control body ( 9 ), characterized in that the inlet opening ( 4 ) communicates with the distribution space ( 7 ) via two guiding channels ( 6 ) which discharge at its front ends ( 61 ,  62 ) into the distribution space ( 7 ) within the region of the outermost connection channels ( 23 ) or outside the region of all connection channels ( 23 ).  
   
   
       23 : Distributor according to  claim 22 , characterized in that the control body ( 9 ) comprises at least one cross-piece ( 14 ) at its circumference which overbridges the distribution space ( 7 ) and surrounds a flush back channel ( 27 ) communicating with the discharge channel ( 28 ), said cross-piece sealingly engaging an area of the inner wall of the housing ( 53 ).  
   
   
       24 : Distributor according to  claim 22 , characterized in that the control body ( 9 ) is a slider ( 37 ) displaceable in the housing ( 53 ) or is a rotary piston ( 8 ) rotatable in the housing ( 53 ), said rotary piston ( 8 ) comprising at least two cross-pieces ( 14 ) which are offset relative to each other both in axial direction and in circumferential direction of the rotary piston ( 8 ).  
   
   
       25 : Distributor according to  claim 22 , characterized in that at least one additional guiding channel ( 60 ) leads into the distribution space ( 7 ) between the two guiding channels ( 6 ) leading to its two front ends ( 61 ,  62 ).  
   
   
       26 : Distributor according to  claim 22 , characterized in that at least two control bodies ( 9 ) are disposed within a common housing ( 53 ), wherein a distribution space ( 7 ) is assigned to each one of these control bodies ( 9 ), which distribution space is supplied in the region of its front ends ( 61 ,  62 ) via guiding channels ( 6 ).