Air filter cartridge for I.C. motors, method for its manufacture and air filter incorporating said cartridge

1. An air filter cartridge for I.C. motors, comprising a body having a parallelepipedal or cubic shape in which there are defined, in the flow direction of the air to be filtered, an upstream face and a downstream face of the cartridge, said body comprising at least a pair of panels of filtering material provided in a substantially V-shaped arrangement, so that at least one channel for the passage of air is defined between the panels of said at least one pair of panels, wherein the filtering material of at least one of the panels comprises a corrugated sheet of filtering material in which, on opposite surfaces thereof, a succession of corrugations and grooves are defined mutually parallel and parallel to said upstream face and said downstream face of the cartridge, wherein at least two of the corrugations have mutually different height, and wherein the grooves defined on an opposite face of a same panel, at the corrugations of different height, have mutually different depths.

2. The cartridge according to claim 1 , wherein the height of the corrugations in at least one portion of at least one of the panels increases progressively from the upstream face to the downstream face of the cartridge or vice-versa.

3. The cartridge according to claim 1 , wherein the filtering material of both panels of the at least one pair of panels comprises a corrugated sheet in which the corrugations have mutually different height.

4. The cartridge according to claim 1 , wherein the panels define an upstream face and a downstream face of the panels in the flow direction of the air to be filtered and wherein said upstream and downstream faces of the panels are mutually non-parallel.

5. The cartridge according to claim 1 , wherein at least one of the panels has a trapezoidal cross-section.

6. The cartridge according to claim 1 , wherein the upstream face of the cartridge is open for allowing entrance of air in the channel defined between the panels and the downstream face of the cartridge is closed for preventing exit of air.

7. An air filter for I.C. motors, comprising a housing provided with an inlet for the air to be filtered and an outlet for the filtered air, and a filter cartridge manufactured in accordance with claim 1 .

8. The filter according to claim 7 , wherein between the cartridge and the housing there is provided a sealing gasket surrounding the upstream face of the body of the cartridge.

9. A method of manufacturing a filter cartridge for I.C. motors, comprising:

providing a sheet of filtering material;

corrugating said sheet so as to form, on opposite surfaces thereof, a succession of corrugations and grooves wherein at least two corrugations have mutually different height;

closing the opposite ends of the grooves so as to obtain a panel ( 19 a , 19 b ) of filtering material;

associating in a V-shaped configuration said corrugated panel with a second panel or folding over itself in a V-shaped configuration said corrugated panel, so as to define a cartridge body having a parallelepipedal or cubic shape wherein there are defined, in the flow direction of the air to be filtered, an upstream face and a downstream face of the cartridge, and a channel between the panels for the passage of air, said corrugations and grooves being mutually parallel and parallel to said upstream face and said downstream face of the cartridge, wherein the step of corrugating the sheet of filtering material is carried out in such a way as to define at least two corrugations of mutually different height and corresponding grooves defined on an opposite face of a same panel, at the corrugations of different height, having mutually different depths.

10. The method according to claim 9 , wherein the corrugating the sheet of filtering material takes place by starting from a paper band that is subjected to a folding operation by an electronic knife folding machine capable of folding to a progressively varying height the filtering means thereby originating a continuous series of pleated paper pyramids.

11. The method according to claim 10 , wherein the pleated band is cut to the desired size and after this cutting operation the stack of pleated paper so obtained is introduced into a mold where, owing to the temperature reached and to the deposition of transverse reinforcing beads of glue, the stack is formed and maintained with the pleats correctly distanced.

12. The method according to claim 11 , wherein the stack with the reinforcing beads of glue, is folded over itself substantially in half so as to form a double contiguous trapezium.

13. The method according to claim 12 , wherein the stack is inserted in a reinforcing U-shaped element of wire mesh or of plastics.

14. The method according to claim 13 , wherein the stack is introduced into a rotary machine allowing the closing of the side walls of the stack by a sealing material comprising plates glued to the side walls of the filtering material.

15. The method according to claim 14 , wherein a step is provided of introducing the stack into a mold for foaming a gasket made of polyurethane, for sealing the cartridge thus obtained with the housing in which it will be received.

16. The cartridge according to claim 2 , wherein the filtering material of both panels of the at least one pair of panels comprises a corrugated sheet in which the corrugations have mutually different height.