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1. EP0984824 - BAR SCREEN WITH ROTATING RAKES

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters
Claims

1. A mechanically raked screen system for removing solids from a flowing liquid, comprising:

a screen (2) of a multiplicity of mutually parallel screen bars (14), said screen bars (14) being oriented substantially transversely relative to a flow direction of a flowing liquid and forming screen spaces of a given width therebetween;

a rake assembly for raking solids from said screen (2) and driven by a reversible driving device;

an overload sensor system for the rake assembly, for reversing the driving device when an obstacle is sensed at the screen (2); and

an upper scraper mechanism (18, 19) for discharging the raked solids;

characterized in that

said rake assembly includes two endless chains (4) driven by an electic motor (6) and traveling about sprocket wheels (5) disposed laterally of said screen (2), and a plurality of rakes (3) attached to and extending between said chains (4), said rakes (3) being oriented substantially perpendicularly to said screen bars (14) and traveling with said chains (4) for repeatedly raking said screen (2);

in that a current sensor system (STR, LMI) is connected to said electric motor (6), said current sensor system (STR, LMI) determining whether or not the rakes (3) have been stopped at an obstacle by means of measuring an overload current of the electric motor (6) driving the chains (4), a switching device (KX-10R) being responsive to the current sensor system output for repeatedly reversing the sense of rotation of the motor (6), to reverse the direction of travel of the rakes (3) until a measurement of the overload current indicates that the obstacle has been removed;

and in that each of said rakes (3) has tynes (10) having a width of between 4 mm and 8 mm, and being integrally formed and protruding into said screen spaces, each of said rakes (3) together with its tynes (10) being formed from a single metal component (11).


  2. The screen system according to claim 1, characterized in that said screen bars (14) are trapezoidal as seen in a horizontal cross section, having a wider side thereof facing against a flow direction of a liquid flowing through said screen (2) and tapering towards a narrower side thereof as seen in the flow direction.
  3. The screen system according to claim 2, characterized in that said wider sides of said trapezoidal screen bars (14) have a width approximately double the width of said narrower side thereof.
  4. The screen system according to any of claims 1 to 3,
characterized in that a respective U-rail (13) is welded to the back of each of said rakes (3), as seen in the rake travel direction.