Filter unit on equipment requiring ventilation free of dust and impurities during operation

Claim 1

Filter device on electrical switch cabinets, housings for electronic systems and like equipment to be maintained free of dust and impurities while being ventilated during operation, comprising a labyrinth filter disposed in a travel path of ventilating air upstream of an air intake opening of the equipment to be ventilated, said labyrinth filter having means for effecting a plurality of sharp changes in direction of flow of the ventilating air therethrough so as to function in a manner similar to that of a mechanical labyrinth seal, said labyrinth filter being of bipartite construction and comprising interlocking lower and upper parts formed with comb-type segments for blocking particles in the ventilating air flow and depositing the particles under the influence of gravity in lower regions of said lower parts, said labyrinth filter being constructed as an attachment for a personal computer, said lower part of said labyrinth filter being secured by adhesive to an upper side of the personal computer, and said upper part of said labyringh filter being superimposed on said lower part thereof and being matched by suitable shaping of outer contours thereof to the shape of the housing of the personal computer, and including corresponding lugs and bores formed in webs as well as press-fitted magnetic inserts with metallic counter members cooperating therewith carried by said upper and said lower parts of said labyrinth filter for forming an exact-fit and quick-release connection of said upper and said lower parts.