Filter mounting frame

A filter assembly for use in an air purifier unit having a rectangular shaped air inlet entrance to the unit blower. A rectangular shaped frame containing a HEPA filter pack is slidably received within the blower inlet. An L-shaped flange surrounds the filter frame and closes against the air inlet of the blower to provide an air seal. The top wall of the flange is offset some distance from an adjacent wall of the frame to provide a handle for the filter assembly.

BACKGROUND OF THE INVENTION 
This invention relates to an air purifier unit and, in particular, to a 
high efficiency filter assembly for use in a portable air purifying unit. 
As the air we breathe becomes more contaminated, the need for better, 
higher efficiency air purification equipment becomes more pronounced, 
particularly in the more densely populated areas. Much of the air 
pollution in these populated regions is caused by automobile exhaust 
emissions and industrial plants that burn fossil fuel in order to satisfy 
their power demands. This type of pollution is difficult to cleanse from 
the air and cannot be effectively handled by conventional filter found in 
furnace and air conditioning systems. As a consequence, people who suffer 
from respiratory ailments are oftentimes forced to remain indoors when the 
air quality drops below a certain safe value. Ideally, while indoors, 
these people should breathe air that has been circulated through a high 
efficiency air purifying system. This type of system is typically costly 
and not easily transported from place to place. Inexpensive portable units 
are available, however, the dependability and operability of these units 
is sometimes less than satisfactory. 
A new high efficiency particle arrestor (HEPA) filter pack has been 
developed which is suitable for use in portable air handling units and, in 
particular, in an air purification system. The filter material is 
contained in a rectangular shaped package. The package, however, has 
relatively little structural strength and poses certain difficulties 
relating to securing it within a unit and in handling the package during 
installation and removal from a unit so that the filter is not damaged. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to improve air handling 
equipment and, in particular, air purification units. 
A further object of the present invention is to provide a frame for a HEPA 
filter pack that protects the pack and which is easily handled during 
installation and removal from an air purification unit. 
Yet a still further object of the invention is to provide a filter assembly 
containing a HEPA filter pack that is capable of providing a positive air 
seal with an air inlet of a blower system employed in an air purification 
system. 
Another object of the present invention is to minimize the amount of air 
bypassing the filter installed in an air handling unit. 
Yet another object of the present invention is to provide a filter assembly 
for installation in a portable air purifier that has a built-in safety 
feature for inactivating the blower motor of the system when the filter is 
misaligned or removed from the system. 
These and other objects of the present invention are attained by a filter 
assembly for installation in an air purification unit that has a 
rectangular air inlet to the system blower. The filter assembly includes a 
rectangular frame for housing a HEPA filter pack. An L-shaped flange 
surrounds the frame and opens toward the front of the frame. The flange is 
adapted to receive the front edge of the blower inlet therein. The front 
edge of the air inlet closes against the back wall of the flange to 
prevent air drawn into the assembly by the blower from leaking by the 
flange. The flange is extended outwardly above the top wall of the filter 
frame to provide a handle for carrying the filter assembly and 
facilitating installation and removal of the assembly from the unit.

DESCRIPTION OF THE INVENTION 
Turning now to FIGS. 1-3, there is shown an air purification unit, 
generally referenced 10, that embodies the teachings of the present 
invention. The unit includes a housing 11 containing a main support member 
12 for supporting the component parts of the air purifying equipment and 
the housing covers that enclose the equipment. The support member is a 
rectangular shaped element containing a top wall 14, a bottom wall 15 and 
opposed side walls 16. An inner wall 17 is integrally joined to the other 
walls and has a central orifice 19 formed therein. A blower motor 20 is 
mounted upon a bracket on the front face of the inner wall. A scroll 23 is 
formed in the back face of the inner wall around the orifice and the motor 
shaft 24 is arranged to pass through the orifice into the scroll. A fan 25 
is secured to the motor shaft and is fully contained inside the scroll. 
The front edge section of the main support frame serves as the air inlet 
to the blower. A rear cover 27 is affixed to the back of the support frame 
that contains a back panel 28 that encloses both the back of the scroll 
and a scroll discharge opening 29 formed in the top wall of the main 
support member to create an airtight passage therethrough. 
A top cover 30 is secured to the top wall of the support member which 
contains an air discharge vent 31. A front cover 32 is removably fitted 
over the front of the support member and coacts with the other covers to 
close the housing. The front panel 33 of the front cover contains an air 
inlet vent 34 which permits ambient air to be drawn by the fan into the 
housing. 
A filter assembly, generally referenced 35, is removably contained within 
the air inlet section of the support member and a includes rectangular 
filter frame 36 that is slidably received in the rectangular shaped air 
inlet to the blower. 
With further reference to FIGS. 4-8, the filter assembly includes a molded 
frame 36 having a top wall 38, a bottom wall 39 and a pair of opposed side 
walls 40. An inwardly extended lip 41 depends from the front edge of each 
wall to provide additional strength and rigidity to the filter frame. A 
filter pack 45 is mounted inside the filter frame and is sealed to the 
interior surfaces of the frame walls by means of a hot-melt glue 46 (FIG. 
8) to provide an airtight joint between the filter frame and the filter 
pack. A HEPA filter 47 is contained in the pack for removing fine 
particulates and other contaminants from the air stream drawn through the 
filter by the blower. As will be explained in greater detail below, the 
filter pack can be easily removed from the blower assembly to be cleaned 
or replaced depending on the nature of the filter material. 
An L-shaped flange 50 (FIG. 7) surrounds the outside of the filter frame. 
The flange includes a continuous back wall 51 that is perpendicularly 
aligned with the walls of the frame and a continuous upper wall 52 that 
parallels the walls of the frame. The flange opens towards the front of 
the frame and is adapted to slidably receive therein the rectangular front 
edge of the air inlet to the blower at the front of the main support 
member. In assembly, the front edge of the air inlet closes against the 
back wall of the flange to form a seal for preventing the air that is 
being drawn through the filter from escaping from the filter assembly. 
The upper wall 52 (FIG. 8) of the flange is offset a greater distance from 
the top wall 38 of the filter frame than from the other sections of the 
flange. Sufficient room is provided between the upper wall of the flange 
and the top wall of the filter frame to allow the flange in this region to 
be securely grasped to facilitate installation and removal of the assembly 
from the blower unit as well as carrying the assembly. 
Ribs 63 are mounted on the top wall of the filter frame inside the flange. 
Sufficient space is provided between the top surfaces of the ribs and the 
inside surface of the flange upper surfaces to permit the top wall of the 
main support member to pass therebetween. The ribs help to locate and 
align the frame with respect to the blower air inlet during installation 
of the filter assembly. A generous radius 65 is formed at the top front 
edge of each rib to help guide the front edge of the blower air inlet 
under the flange. A close sliding fit is provided between the top of the 
flange and the remaining walls of the main support frame so that the 
filter frame fits snugly over the air inlet of the blower. 
Turning now to FIG. 9, a tab 70 is mounted upon the front lip associated 
with the top wall of the filter frame. At assembly, the tab that is 
arranged to pass through an opening 71 in the support member into contact 
with a safety switch 73 contained behind the opening to close the switch 
and thus provide power to the blower motor. Removal of the filter frame 
from the unit opens the switch thus disconnecting the motor from its power 
supply. 
Preferably, the parts of the filter frame which include the walls, the 
flange, the front lip, the ribs and the tab are all integrally molded from 
a high strength plastic. 
While this invention has been explained with reference to the structure 
disclosed herein, it is not confined to the details set forth and this 
invention is intended to cover any modifications and changes as may come 
within the scope of the following claims: