Plastic Injection Molded Furnace Filter

1. Field of the Invention

The present invention generally relates to a fluid filter. More specifically, the present invention is drawn to a plastic injection molded frame for holding air filter media in a furnace.

2. Description of the Related Art

Almost all central air heating systems used in modern homes require an air filter. The purpose of the air filter is to rid the incoming air of dust and pollen which may cause breathing difficulties. Filtering the incoming air is especially critical for those who suffer from allergic reactions which are triggered by pollen/dust borne air.

Many heating systems position the air filter in a guide track located in the air inlet duct. Typically, the air filter is a unit comprising filter media encased in a cardboard frame and covered with wire mesh. When the filter media becomes laden with pollen and dust, the entire unit (cardboard frame, wire mesh, and filter media) is removed from the guide track for disposal and replaced with a new unit. The above filter replacement process is expensive in that the relatively costly cardboard frame and wire mesh are wastefully disposed.

The following patents show other types of air filter arrangements. U.S. Pat. No. 3,076,303 (Durgeloh) discloses air filter media encased around its perimeter by a plastic frame. U.S. Pat. No. 5,464,461 (Whitson et al.) discloses an air filter unit for an avionic line replacement unit box. U.S. Pat. No. 5,725,623 (Bowerman et al.) discloses an air filter unit for a vacuum cleaner. Japanese Patent 62-74426 discloses media encased around its perimeter by a metallic frame.

None of the above inventions and patents, taken either singularly or in combination, is seen to disclose a plastic injection molded furnace filter unit as will be described and claimed in the present invention.

The present invention comprises a rectangular shaped, injection molded plastic grid structure. The structure includes two identical grid frames fastened together at one side with a hinge. The hinge is made of the same plastic as the frames and is integral therewith, thereby forming a living hinge. Filter media is disposed between the two frames such that the filter media will be pinched between the frames when the frames are folded at the hinge, thus forming a filter unit. The formed filter unit is adapted to be inserted into the filter track of a furnace's air inlet duct. The filter track will automatically hold the unit in its folded position in the air inlet duct. Because the molded frame is reusable, only the filter media need be replaced when necessary. The molded frame is sized to fit the popular standard 20.times.25 inch air duct track. It is obvious, however, that the frame may be easily cut to fit smaller track dimensions.

Accordingly, it is a principal object of the invention to provide an air filter unit adapted for insertion in a standard sized track of a furnace air duct.

It is another object of the invention to provide an air filter unit having a reusable molded frame.

It is a further object of the invention to provide an air filter unit which can be easily cut to fit air duct tracks having dimensions smaller than standard.

Still another object of the invention is to provide an air filter which requires replacement of only the air filter media.

It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which are inexpensive, dependable and fully effective in accomplishing their intended purposes.

These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.

FIG. 1 is an environmental, perspective view of a plastic injection molded furnace filter according to the present invention.

FIG. 2 is a perspective view of the grid structure with a partially inserted media filter according to the present invention.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

The present invention, as illustrated in FIGS. 1 and 2, is drawn to an air filter unit generally indicated at 10. The filter unit 10 comprises filter media 12 enclosed in a molded plastic grid structure 14. Filter unit 10 is adapted to be inserted into the filter track 16 of a furnace air duct 18.

As best seen in FIG. 2, grid 14 is formed as two rectangularly shaped identical frame members 20 and 22. Members 20 and 22 are joined at one side with a hinge 24. Members 20, 22, and hinge 24 are integrally made of the same plastic material and are preferably formed by an injection molding process, forming the living hinge 24.

Hinge 24 allows members 20 and 22 to be folded in a manner to capture and compress the filter media 12 therebetween. Filter media 12 may comprise any of the fibrous and/or synthetic materials well known in the filter art. Members 20 and 22 are retained in the folded position by the walls of the filter track 16. The filter media, compressed between members 20 and 22, functions to form an effective seal which minimizes air leakage from filter track 16 while allowing air to flow perpendicularly therethrough.

In use, filter media 12 is placed between grid members 20, 22 and the unit is inserted in filter track 16. When the filter media becomes saturated with dust and pollen, the unit is removed and the filter media is replaced. The grid 14 is reusable for essentially a lifetime under normal conditions. As mentioned above, the grid 14 is sized to fit a standard 20.times.25 inch filter track. By merely using a sharp pair of shears a homeowner may trim the grid to fit tracks smaller than the popular standard.

It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.