Nesting air filters

Claim 2

In a stack of air filters each including a filter element of fibrous material and a quadrangular frame for supporting said filter element at its marginal edges, the improvement comprising: a set of recesses formed in each filter frame at positions adjacent to diagonally opposite corners of said frame, each of said recesses being adapted to receive the frame of another air filter, said air filters being stacked with first and second air filters in the stack overlapped and arranged in a laterally offset relationship and subsequent air filters in the stack also overlapped and arranged in a laterally offset relationship and with the recesses of each air filter receiving the frame of the next air filter in the stack to allow said first and second air filters to nest together and to allow said second air filter and each subsequent air filter to nest with the next air filter in the stack.

Claim 3

A stack of air filters, each including a filter element of fibrous material and a quadrangular frame for supporting the filter element at its marginal edges, comprising: a plurality of air filters arranged in a stack with first and second air filters laterally offset relative to each other and subsequent air filters in the stack also laterally offset relative to each other and with the frames of successive air filters in the stack overlapping at positions adjacent to diagonally opposite corners of the frames; and a plurality of recesses formed in the frames of the air filters at said positions adjacent to the diagonally opposite corners of the overlapping frames, each of said recesses receiving the frame of an adjacent air filter in the stack to allow said first air filter to nest with said second air filter and to allow said second air filter and each subsequent air filter to nest in succession with the next air filter in the stack.

Claim 4

A stack of air filters, each including a filter element of fibrous material and a quadrangular frame for supporting the filter element at its marginal edges, comprising: a plurality of air filters arranged in a stack with first and second air filters laterally offset relative to each other and subsequent air filters in the stack also laterally offset relative to each other and with the frames of successive air filters in the stack overlapping at positions adjacent to diagonally opposite corners of the frames; and a plurality of recesses formed in the frames of the air filters at said positions adjacent to the diagonally opposite corners of the overlapping frames, each of said recesses receiving the frame of an adjacent air filter in the stack to allow said first air filter to nest with said second air filter and to allow said second air filter and each subsequent air filter to nest in succession with the next air filter in the stack.

Claim 5

The air filters of claim 1 or 2, wherein: at least two recesses are formed on the same face of each filter frame and located along adjacent sides of said frame at positions adjacent to said opposite corners.

Claim 6

In a stack of air filters of rectangular shape each including a filter element of fibrous material and a rectangular frame for supporting said filter element at its marginal edges, the improvement comprising: a set of notches formed on each filter frame at positions adjacent to diagonally opposite corners of said frame, each of said notches being shaped to receive the frame of an adjacent air filter of rectangular shape, said air filters being stacked with first and second air filters in the stack laterally offset relative to each other and subsequent air filters alternately aligned with the first and second air filters, respectively, and with the notches of each successive air filter receiving the frame of the next air filter in the stack to allow said first and second air filters to nest together and to allow said second air filter and each subsequent air filter to nest in succession with the next air filter in the stack.

Claim 7

In a stack of air filters of rectangular shape each including a filter element of fibrous material and a rectangular frame for supporting said filter element at its marginal edges, the improvement comprising: a set of notches formed on each filter frame at positions adjacent to diagonally opposite corners of said frame, each of said notches being shaped to receive the frame of an adjacent air filter of rectangular shape, said air filters being stacked with first and second air filters in the stack laterally offset relative to each other and subsequent air filters alternately aligned with the first and second air filters, respectively, and with the notches of each successive air filter receiving the frame of the next air filter in the stack to allow said first and second air filters to nest together and to allow said second air filter and each subsequent air filter to nest in succession with the next air filter in the stack.

Claim 8

A stack of air filters, each including a filter element of fibrous material and a rectangular frame for supporting the filter element at its marginal edges, comprising: a plurality of air filters arranged in a stack with first and second air filters laterally offset relative to each other and subsequent air filters alternately aligned with the first and second air filters, respectively, and with the frame of each air filter overlapping the frames of the adjacent air filters in the stack at positions adjacent to diagonally opposite corners of the frames; and a plurality of notches formed in the frames of the air filters at said positions adjacent to the diagonally opposite corners of the overlapping frames, each of said notches receiving the frame of an adjacent air filter in the stack to allow said first air filter to nest with said second air filter and to allow said second air filter and each subsequent air filter to nest in succession with the next air filters in the stack.

Claim 9

A stack of air filters, each including a filter element of fibrous material and a rectangular frame for supporting the filter element at its marginal edges, comprising: a plurality of air filters arranged in a stack with first and second air filters laterally offset relative to each other and subsequent air filters alternately aligned with the first and second air filters, respectively, and with the frame of each air filter overlapping the frames of the adjacent air filters in the stack at positions adjacent to diagonally opposite corners of the frames; and a plurality of notches formed in the frames of the air filters at said positions adjacent to the diagonally opposite corners of the overlapping frames, each of said notches receiving the frame of an adjacent air filter in the stack to allow said first air filter to nest with said second air filter and to allow said second air filter and each subsequent air filter to nest in succession with the next air filters in the stack.

Claim 10

The air filters of claim 4 or 5, wherein: a pair of notches is formed at each of two diagonally opposite corners of each filter frame with the two notches of each pair located at positions equidistantly spaced from the respective corner along the adjacent sides of said filter frame intersecting at the corner.

Claim 11

The air filters of claim 6, wherein both pairs of notches are formed in the same face of each filter frame.

Claim 12

The air filters of claim 6, wherein one pair of notches is formed on the front and the other pair of notches is formed on the back of each filter frame.

Claim 13

The air filters of claim 5, wherein unnotched air filters are alternately stacked with notched air filters in a laterally offset relationship.

Claim 14

An air filter of rectangular shape adapted to nest with other air filters of the same configuration in a compact space, comprising: a filter element of fibrous material; a paperboard frame for supporting said filter element at its marginal edges; said frame being formed as a trough in cross section and arranged to form a closed, rectangular configuration surrounding said filter element to receive said marginal edges of said filter element in said trough; said frame including an outer wall and a pair of inclined side walls sloping toward each other to receive said filter element therebetween; each of said side walls terminating in a flange disposed substantially at right angles to said outer wall, said flanges being secured together with said filter element compressed therebetween to hold said frame and said filter element together; and a pair of recesses formed at each of two diagonally opposite corners of said frame with the two recesses of each pair located at positions equidistantly spaced from the respective corner along the adjacent sides of said frame intersecting at the corner, each of said recesses comprising a partially cutaway portion of said frame extending into said outer wall and one of said side walls of said frame, said flange of said one side wall remaining intact therewith and secured to said flange of said other side wall adjacent to said recess to maintain the rigidity of said frame, each recess being shaped to receive the frame of another air filter of the same quadrangular shape with the filters arranged in an overlapping, laterally offset relationship to allow said filters to nest together in a compact space.

Claim 15

An air filter of rectangular shape adapted to nest with other air filters of the same configuration in a compact space, comprising: a filter element of fibrous material; a paperboard frame for supporting said filter element at its marginal edges; said frame being formed as a trough in cross section and arranged to form a closed, rectangular configuration surrounding said filter element to receive said marginal edges of said filter element in said trough; said frame including an outer wall and a pair of inclined side walls sloping toward each other to receive said filter element therebetween; each of said side walls terminating in a flange disposed substantially at right angles to said outer wall, said flanges being secured together with said filter element compressed therebetween to hold said frame and said filter element together; and a pair of recesses formed at each of two diagonally opposite corners of said frame with the two recesses of each pair located at positions equidistantly spaced from the respective corner along the adjacent sides of said frame intersecting at the corner, each of said recesses comprising a partially cutaway portion of said frame extending into said outer wall and one of said side walls of said frame, said flange of said one side wall remaining intact therewith and secured to said flange of said other side wall adjacent to said recess to maintain the rigidity of said frame, each recess being shaped to receive the frame of another air filter of the same quadrangular shape with the filters arranged in an overlapping, laterally offset relationship to allow said filters to nest together in a compact space.

Claim 16

The air filter of claim 10, wherein both pairs of recesses are formed on the same face of said filter frame.

Claim 17

The air filter of claim 10, wherein one pair of recesses is formed on the front and the other pair of recesses is formed on the back of said filter frame.

Claim 18

An air filter of rectangular shape adapted to nest with another air filter of the same configuration in a compact space, comprising: a filter element of fibrous material; a paperboard frame for supporting said filter element at its marginal edges; said frame being formed as a trough in cross section and arranged to form a closed, rectangular configuration surrounding said filter element to receive said marginal edges of said filter element in said trough; said frame including an outer wall and a pair of inclined side walls sloping toward each other to receive said filter element therebetween; each of said side walls terminating in a flange disposed substantially at right angles to said outer wall, said flanges being secured together with said filter element compressed therebetween to hold said frame and said filter element together; and said frame including a set of recesses formed at positions adjacent to diagonally opposite corners of said frame, each of said recesses comprising a partially cutaway portion of said frame extending into said outer wall and one of said side walls of said frame, said flange of said one side wall remaining intact therewith and secured to said flange of said other side wall adjacent to said recess to maintain the rigidity of said frame, each recess being shaped to receive the frame of another air filter of the same rectangular shape with the filters arranged in an overlapping, laterally offset relationship to allow said filters to nest together in a compact space.

Claim 19

An air filter of rectangular shape adapted to nest with another air filter of the same configuration in a compact space, comprising: a filter element of fibrous material; a paperboard frame for supporting said filter element at its marginal edges; said frame being formed as a trough in cross section and arranged to form a closed, rectangular configuration surrounding said filter element to receive said marginal edges of said filter element in said trough; said frame including an outer wall and a pair of inclined side walls sloping toward each other to receive said filter element therebetween; each of said side walls terminating in a flange disposed substantially at right angles to said outer wall, said flanges being secured together with said filter element compressed therebetween to hold said frame and said filter element together; and said frame including a set of recesses formed at positions adjacent to diagonally opposite corners of said frame, each of said recesses comprising a partially cutaway portion of said frame extending into said outer wall and one of said side walls of said frame, said flange of said one side wall remaining intact therewith and secured to said flange of said other side wall adjacent to said recess to maintain the rigidity of said frame, each recess being shaped to receive the frame of another air filter of the same rectangular shape with the filters arranged in an overlapping, laterally offset relationship to allow said filters to nest together in a compact space.

Claim 20

An air filter of rectangular shape adapted to nest with another air filter of the same configuration in a compact space, comprising: a filter element of fibrous material; a paperboard frame for supporting said filter element at its marginal edges; said frame being formed as a trough in cross section and arranged to form a closed, rectangular configuration surrounding said filter element to receive said marginal edges of said filter element in said trough; said frame including an outer wall, a first side wall extending perpendicularly inward from said outer wall toward said filter element, and a second side wall extending inward from said outer wall toward said filter element and sloping toward said first side wall; said second side wall terminating in a flange disposed in a parallel relationship with said first side wall, said flange being secured to said first side wall with said filter element compressed therebetween to hold said frame and said filter element together; and said frame including a set of recesses formed at positions adjacent to diagonally opposite corners of said frame, each of said recesses comprising a partially cutaway portion of said frame extending into said outer wall and said second side wall of said frame, said flange of said second side wall remaining intact therewith and secured to said first side wall adjacent to said recess to maintain the rigidity of the frame, each recess being shaped to receive the frame of another air filter of the same rectangular shape with the filters arranged in an overlapping, laterally offset relationship to allow said filters to nest together in a compact space.

Claim 21

An air filter of rectangular shape adapted to nest with another air filter of the same configuration in a compact space, comprising: a filter element of fibrous material; a paperboard frame for supporting said filter element at its marginal edges; said frame being formed as a trough in cross section and arranged to form a closed, rectangular configuration surrounding said filter element to receive said marginal edges of said filter element in said trough; said frame including an outer wall, a first side wall extending perpendicularly inward from said outer wall toward said filter element, and a second side wall extending inward from said outer wall toward said filter element and sloping toward said first side wall; said second side wall terminating in a flange disposed in a parallel relationship with said first side wall, said flange being secured to said first side wall with said filter element compressed therebetween to hold said frame and said filter element together; and said frame including a set of recesses formed at positions adjacent to diagonally opposite corners of said frame, each of said recesses comprising a partially cutaway portion of said frame extending into said outer wall and said second side wall of said frame, said flange of said second side wall remaining intact therewith and secured to said first side wall adjacent to said recess to maintain the rigidity of the frame, each recess being shaped to receive the frame of another air filter of the same rectangular shape with the filters arranged in an overlapping, laterally offset relationship to allow said filters to nest together in a compact space.

Claim 22

The air filter of claim 13 and 14, wherein: each cutaway portion of said filter frame extends from said flange through said side wall into said outer wall of said frame.

Claim 23

The air filter of claim 15, wherein: each cutaway portion of said filter frame is rectangular in configuration.

Claim 28

The method of claim 17 or 18, wherein: at least two recesses are formed on the same face of each filter frame and located along adjacent sides of said frame at positions adjacent to said opposite corners.

Claim 33

The method of claim 20 or 21, wherein a pair of notches is formed at each of two diagonally opposite corners of each filter frame with the two notches of each pair located at positions equidistantly spaced from the respective corner along the adjacent sides of said filter frame intersecting at the corner.

Claim 34

The method of claim 22, wherein both pairs of notches are formed on the same face of each filter frame.

Claim 35

The method of claim 22, wherein one pair of notches is formed on the front and the other pair of notches is formed on the back of each filter frame.

Claim 36

The method of claim 21, wherein unnotched air filters are alternately stacked with notched air filters in a laterally offset relationship.