Odor filter apparatus

1. An odor filter apparatus for a litter box, the odor filter apparatus comprising:

a rear wall, the rear wall configured to rigidly attach to at least one wall of a litter box, wherein the litter box consists of a bottom surface, and at least one wall extending up from the bottom surface, and where the interior of the at least one wall and the interior of the bottom surface are configured to hold and abut against an amount of cat litter suitable for a cat to use for expressing urine and feces;

a first side wall located on one side of the rear wall, and orientated orthogonally to the rear wall, the first side wall configured to rigidly attach to the at least one wall of the litter box;

a second side wall located on an opposite side of the rear wall from the first side wall, and orientated orthogonally to the rear wall the first side wall configured to rigidly attach to the at least one wall of the litter box;

a vent located in the rear wall, the vent having an outer perimeter;

a filter housing attached to the rear wall, on a side opposite the first and second side walls, the filter housing having an outer perimeter;

an active odor removing element located in the filter housing;

a fan assembly housing removeably attached to the filter housing, the fan assembly housing having an outer perimeter;

a blower fan located in the fan assembly housing;

a mounting opening in the fan assembly housing;

a fan exhaust sealing device attached to the mounting opening, the fan exhaust sealing device comprising:

a base portion;

an insertion portion extending out from the base portion;

a lip located on the perimeter of the insertion portion; and wherein the insertion portion and lip extend through the mounting opening, and the base portion remains in the fan assembly housing;

wherein the mounting opening has a length LO, and a width WO, the lip has a length LL and width WL, the non-lip part of the insertion portion has a length LI and width WI, the base portion has a length LB and width WB, and wherein LL and WL will be slightly larger than LO and WO, respectively; LI and WI will be slightly smaller than LL and WL, respectively, and LI and WI will be about the same or slightly smaller than LO and WO, and LB and WB will be generally larger than LO and WO, respectively; and

wherein the blower fan is configured to pull air through the vent, through the active odor removing element, and out through the fan exhaust sealing device; and wherein the outer perimeter of the vent is generally the same size and shape as the outer perimeter of the filter housing and the fan assembly housing.

2. The odor filter apparatus of claim 1 , further comprising:

a dust filter located in the filter housing and adjacent to the active odor removing element;

a protective screen located in the filter housing and adjacent to the active odor removing element and on a side of the active odor removing element opposite the dust filter, the protective screen orientated to be between an animal in the litter box and the active odor removing element when in use.

3. The odor filter apparatus of claim 1 , wherein the non-lip part of the insertion portion with the length LI and width WI is a recess.

4. The odor filter apparatus of claim 1 , wherein the fan exhaust sealing device is made out of a low Durometer material with Shore A hardness of about 30 to about 40.

5. The odor filter apparatus of claim 1 , wherein the fan exhaust sealing device is made out of Neoprene or Silicone Rubber.