Portable room air purifier

A portable and compact room air purifier having an internal filter element through which air is drawn by a centrifugal fan and wherein the air is discharged generally uniformly and radially by passing between at least one generally arcuate scroll and a surrounding deflector. The purifier is automatically deactivated in the event of destruction or removal of the filter housing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is generally directed to portable room air purifiers and 
more specifically to a compact portable room air purifier wherein air is 
discharged after passing through a filter element through a scroll outlet 
where the air is generally directed tangently with respect to the axis of 
rotation of a fan used for conveying air therethrough. An outer deflector 
wall is mounted in spaced and converging relationship with respect to the 
scroll wall so as to define a tapering passageway through which the air is 
exhausted generally radially of the unit. In the preferred embodiment, the 
filter element is a HEPA filter of cylindrical configuration which is 
mounted within a cover. A motor is mounted centrally of the filter element 
for driving the fan. The deflector wall is designed to provide a 
substantially annular opening through which air is exhausted as it is 
channelled generally circumferentially about the base of the unit. 
In the preferred embodiment, the cover is interlocked with a base member 
with an electrical switch being positioned to deactivate power to the 
motor in the event the cover is removed or unlocked from the base or in 
the event the cover becomes shattered thereby releasing pressure of the 
cover relative to the base thus providing safety and eliminating any 
possibility of injury from accidental contact with the fan. 
In some embodiments, two or more scrolls and/or deflectors may be utilized 
to distribute the air generally evenly with respect to the periphery of 
the unit. 
2. History of the Related Art 
There is an ever increasing need to provide clean air environments both at 
home and in the work place. Especially in urban areas where pollutant 
levels are in excess of those recommended for good health, it is necessary 
to upgrade living and work environments by removing harmful contaminants 
from the air. 
Airborne pollutants contribute to respiratory infections and illnesses and 
can be especially damaging to individuals with respiratory problems 
including allergies or from Asthma. Symptoms of high pollutant levels are 
burning eyes, nose and throat irritations, headaches, dizziness, coughing 
and sneezing. Individuals are constantly inhaling particles of dust, 
smoke, pollen, mold spores, acids, bacteria, viruses, animal hair, soot, 
and harmful chemicals. 
In an effort to provide some relief from airborne pollutants, many offices 
and homes utilize central filtering systems to remove particles from the 
air. Unfortunately, such centralized systems, which are economically 
available, do not remove more than approximately 80-85% of the particles 
in the air and are only effective on particles which are approximately one 
micron or larger. 
The need to have substantially purified air has resulted in the creation of 
special filter elements which are defined as HEPA filters. HEPA stands for 
High Efficiency Particulate Air filters which by, federal standard, are 
filters with a minimum efficiency of 99.97%. The industry defines HEPA 
filters as those filters which are efficient in removing 99.97% of 
airborne particles of a size of 0.3 micron or larger. 
Although such HEPA filter elements where originally designed for use in 
ultra clean environments including laboratories, electronic and 
biologically clean rooms, hospitals and the like, such filters have been 
used in portable structures which may be utilized in individual room 
environments. 
In U.S. Pat. No. 4,629,482 to George B. Davis, one type of portable HEPA 
room air purifier is disclosed which has specific utility in allowing for 
a fairly uniformed distribution of filtered air from the unit and wherein 
the unit is designed to provide an indication of when the filter cartridge 
is becoming clogged and should be replaced. The unit incorporates a 
cylindrical HEPA filter so as to increase the overall surface area of the 
filter material and the filter is mounted within a housing having an 
annular discharge adjacent its base. A centrifugal fan is utilized to draw 
air through the filter and discharge the air radially outwardly of the 
annular discharge. Due to the configuration of the unit, it is necessary 
to space the base of the apparatus from the main housing in which the 
cylindrical filter is mounted which requires that the apparatus be 
designed somewhat larger than some consumers may prefer. 
In view of the foregoing, it has become necessary to overcome the physical 
detriments of prior art portable filter structures by providing compact 
portable units without however, affecting the capability of the units to 
uniformly distribute and filter air within a room. 
SUMMARY OF THE INVENTION 
This invention is generally directed to compact portable room air purifiers 
having a housing in which a filter element is positioned so as to be 
intermediate an air inlet and an air outlet and wherein a fan is driven by 
a motor so as to urge air inwardly through the inlet and discharge the air 
towards the outlet. The portable room air purifiers further include at 
least one scroll which is oriented so as to direct air from the fan 
generally tangently with respect to the axis of the fan through a scroll 
discharge opening. A deflector is mounted in spaced relationship with 
respect to the discharge opening and the deflector tapers inwardly 
relative to the scroll to thereby define an open passageway through which 
air is directed as it is exhausted through the air outlet. 
In some embodiments, a single scroll of generally arcuate configuration may 
be utilize to discharge air towards a generally circular deflector which 
extends in surrounding relationship with respect to the scroll but which 
tapers inwardly towards the scroll away from the discharge opening formed 
by the scroll so that air being discharged is partially channelled about 
the unit as it is exhausted therefrom. In other embodiments, two or more 
scrolls may be utilized, each of which is generally arcuate. In this 
manner, at least two (2) exhaust openings are created by the scrolls with 
the exhaust openings being spaced from the deflector wall so as to form 
separate conveying passageways through which air is discharged from the 
filter unit. 
In the preferred embodiment, the housing is generally cylindrical so that 
the passageways formed between the scrolls and the deflector wall are also 
generally arcuate thereby providing for discharge generally around the 
entire periphery of the unit. 
The portable room air purifier also incorporates a HEPA filter element of 
cylindrical configuration which is mounted to a support seated on the 
scroll. A motor to drive a centrifugal fan is mounted centrally of the 
filter element so as to provide a compact configuration for the apparatus. 
To insure that the unit may be safely operated in environments where 
children are present, the housing includes a cover which is interlocked to 
a base with a safety switch being mounted so as to terminate power to the 
motor in the event the cover is unlocked or loosened with respect to the 
base or otherwise compromised such as by an accidental fracturing of the 
cover. 
It is the primary object of the present invention to provide a very compact 
portable room air purifier wherein the discharge of air is generally 
radially outwardly about the entire periphery of the unit so that a 
uniform distribution of filtered air is accomplished within an area in 
which the unit is operated. 
It is another object of the present invention to provide a portable compact 
room air purifier which may be economically constructed so that it may be 
available to a greater portion of the consuming public and wherein the 
unit is designed to prevent operation of the motor and fan in the event 
any effort is made to access the interior of the unit by removing the 
cover or wherein the unit is automatically deactivated upon the 
destruction of the housing. 
It is also an object of the present invention to provide a compact portable 
room air purifier which incorporates a cylindrical HEPA filter element 
which is effective to remove 99.97% of the particles of 0.3 micron or 
larger from the air in a room in which the unit is operated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With continued reference to the drawings, the compact portable room air 
purifier of the present invention 10 is shown as including a cover 11 
which is selectively mounted to a base 12. An "ON-OFF" and speed control 
switch 13 extends through the top of the central portion of the cover and 
includes an operating handle 14 which is recessed within a recess 15 so as 
to be substantially flush with the contour of the upper surface. In the 
embodiment shown in FIGS. 1-4, the cover is molded of two (2) half 
sections which are assembled along a weld line 16. The cover includes a 
plurality of outwardly extending fins 17 which define a plurality of air 
inlet openings 18 which are vertically and horizontally spaced about the 
upper portion of the cover and also define a plurality of air outlet 
openings 19 adjacent to and about the lower portion of the cover. As 
shown, the air inlet openings 18 and the outlet openings 19 are provided 
about the entire periphery of the cover. The horizontal fins 17 are 
reinforced at spaced intervals around the circumference of the cover by 
vertically extending ribs 20 which are integrally molded therewith. 
Mounted within the cover is a bracket assembly 21 having an annular open 
base portion 22 and a plurality of vertically extending and spaced leg 
portions 23. The bracket assembly further includes an upper electrical 
housing 24 in which is mounted the "ON-OFF" and speed control switch 13. 
The switch 13 is electrically connected through electrical wires (not 
shown) to an electric motor 26. The motor is suspended by a plurality of 
pins 27 which extend through openings 28 in each of the legs 23 of the 
bracket assembly and are secured by conventional fastening elements or 
welded thereto. The motor is mounted generally centrally of the cover and 
includes a drive shaft 29 which extends downwardly towards the base 12 of 
the unit. A generally cylindrical HEPA filter element 30 is seated in 
surrounding relationship with respect to the motor and is engaged between 
the top of the cover and the annular base portion 22 of the bracket 
assembly. The HEPA filter element includes upper and lower annular seals 
31 which are formed of a resilient or elastomeric material. The structure 
of the filters may vary, however, it is generally preferred that the 
filter elements include a plurality of vertically extending pleated 
portions of the type disclosed in U.S. Pat. No. 4,629,482, the subject 
matter of which is incorporated herein by reference. 
A centrifugal fan 32 is mounted to the drive shaft 29 of the motor 26. The 
centrifugal fan may include a plurality of radially spaced blades 33. It 
should be noted that the term "centrifugal fan" includes other types of 
fans known in the industry as forward curved, radial and backward inclined 
and that the fan structure may change without departing from the inventive 
characteristics of the present invention. As shown in FIG. 2, the 
centrifugal fan 32 is disposed within a cavity 34 defined by the base 12. 
The base 12 includes a bottom wall 35 and a pair of annular side walls 36 
and 37 which form a generally U-shaped trough which is molded at 38 so as 
to form contoured handles for lifting the air purifier. The base further 
includes an annular deflector wall 40 which extends upwardly from the 
bottom wall 35 but terminates in spaced relationship with respect to the 
annular base portion 22 of the bracket assembly 21. An annular seat 39 is 
formed between the deflector wall 40 and side wall 37. The deflector wall 
40 extends along an imaginary circle having its axis located at the center 
point of the base 35. Extending upwardly from the base 35 interiorly of 
the deflector wall 40 are a pair of scrolls 41 and 42 each of which 
include first and second ends 43, 44, 45 and 46, respectively. The scrolls 
are spaced from another adjacent their ends so as to form exhaust openings 
47 and 48 through which air is directed generally tangently with respect 
to the rotational axis of the centrifugal fan. Each of the scrolls 41 and 
42 is generally arcuately configured although they need not be arc 
segments of a circle per se so that the ends 43 and 45 may flare outwardly 
from a true circle. With particular reference to FIG. 2 of the drawings, 
it should be noted that the scrolls 41 and 42 extend upwardly above the 
upper edge of the deflector wall 40, and in the embodiment shown, provide 
support for the annular base portion 22 of the bracket assembly 21. 
With particular reference to FIG. 4, the relationship between the scrolls 
41 and 42 and the deflector wall 40 is such as to define a pair of arcuate 
and inwardly tapering passageways 49 and 50, each of which is open along 
its entire length along the upper portion thereof so as to communicate 
with the air outlets 19 formed in the cover 11. In this manner, as air is 
discharged outwardly through the exhaust openings 47 and 48 as shown by 
the arrows in FIG. 4, a certain portion of the air will be vented 
immediately through the adjacent air outlets 19 however, a portion of the 
air will be channelled along the passageways 49 and 50 which converge 
relative to one another thereby forcing the air upwardly and outwardly 
through the downstream air outlets 19. In this manner, a generally 
uniformed outward distribution of radial flow of air is created from the 
openings 19. Without the relationship between the scrolls and the 
deflector, the air would be directed outwardly of the unit in two (2) 
directions as shown by the dotted lines extending from the outlet openings 
47 and 48. Such flow would not create uniform air distribution within a 
room in which the unit is operating. 
The structure of the embodiment disclosed in FIGS. 1-4 includes two scrolls 
with a single deflector to establish a uniform distribution of exhaust 
flow from the unit around the periphery thereof. It should be noted that 
in some instances, a single scroll and deflector arrangement may be 
utilized and in other instances 3, 4 or more scrolls may be utilized with 
one or more deflectors to accomplish the air distribution taught by the 
embodiment shown in FIGS. 1-4. 
The cover 11 is locked in covering relationship with respect to the base 12 
by being selectively engaged with the base portion 22 of the bracket 
assembly 21. The bracket assembly is connected to the base by screws (not 
shown) which extend through spaced openings 51 in the base portion thereof 
and into threaded open channels 52 molded at spaced locations along the 
outer walls of each of the scrolls 41 and 42. A plurality of notches 53 
are formed in the periphery of the base portion 22 of the bracket assembly 
which thereby divide the periphery into spaced arcuate locking flanges 54. 
The cover 11 includes a plurality of internally extending locking elements 
55 of a length to be receivable through the notches 53 as the cover is 
seated so that the lowermost fin 17 is seated on base side wall 36 and 
seat 39. Thereafter, by rotating the cover relative to the base, the 
locking element 55 will move out of alignment with the notches and will 
engage the lower surface of the locking flanges 54, as shown in FIG. 2. In 
this position, the cover cannot be directly removed from the base without 
rotating the cover to realign the locking elements 55 with the notches 53. 
The locking relationship between the cover 11 and base 12 also includes a 
safety interlock for preventing the operation of the motor and fan in the 
event the cover is not fully locked in seated relationship to the base. To 
accomplish this, the cover includes at least one, and preferably two or 
more, depending arcuate flanges 56 which extend downwardly from the 
lowermost portion of the base, as shown in FIG. 3A. The flanges 56 are 
designed to depend adjacent base side wall 37 and within the U-shaped 
trough formed between the wall 37 and side wall 36. A power control safety 
switch 70 is mounted within a molded recess 57 formed along a portion of 
the base seat 39 and is retained therein by a cover 71 which is 
threadingly locked to the base by screws "S" which extend into threaded 
mounts 58 which are molded integrally into the base. 
The switch 70 is selectively connected by a conventional power cord (not 
shown) to a source of electrical supply and is connected by electrical 
wires (not shown) to the "ON-OFF" switch 13. 
The switch includes an internal "MAKE-BREAK" contact which is automatically 
returned to a "BREAK" or open condition whereby no power is conveyed to 
the "ON-OFF" switch 13. The internal "MAKE-BREAK" contact includes an 
external spring loaded roller actuator 72. When the roller actuator is 
pushed inwardly toward the switch housing, the "MAKE-BREAK" contact is 
urged into a "MAKE" condition thereby supplying power to the "ON-OFF" 
switch 13. 
When the cover 11 is seated on the base and rotated into locked 
relationship therewith, a depending flange 56 will be guided into a slot 
defined between the side wall 73 of the cover 71 and the outer side wall 
36 of the base wherein the roller actuator 72 is situated. The flange 56 
will engage the roller actuator and retain it against the switch housing 
thereby making the "MAKE-BREAK" contact and supplying power to the 
"ON-OFF" switch 13. When the cover 11 is rotated from a locked 
relationship from the base, the flange 56 will be disengaged from the 
roller actuator thereby breaking the "MAKE-BREAK" contact and 
automatically terminating power to the "ON-OFF" switch 13 so that the 
motor and fan are instantly deactivated. With specific reference to FIG. 
5, a schematic of a modified portable air purification unit 59 is 
disclosed wherein the deflector is formed of a pair of annular walls 60 
and 61 which are vertically spaced from one another so as to define an 
annular air outlet opening 62. In this embodiment, the cover 11 does not 
extend to the air outlet openings as with the previous embodiment and the 
cover merely surrounds the HEPA filter element 30 in a manner similar to 
that disclosed in the aforementioned U.S. Pat. No. 4,629,482. FIG. 5 shows 
the relationship of components wherein a centrifugal fan operating within 
a base 12' would be mounted centrally of a single scroll 64 with the 
scroll having a discharge opening 65 through which filtered air is 
discharged towards the annular outlet opening 62. A secondary plate 66 
which includes the annular wall 62 is mounted in overlying relationship 
with respect to the scroll 64 as shown by the assembly view of FIG. 6. As 
with the previous embodiment, the air that is being discharged through the 
opening 65 is directed into an open tapering passageway 67 which is formed 
between the spaced side walls 61 and 62 of the base and the outer surface 
of the scroll 64. In this manner, some of the air being discharged from 
the opening 65 exits the annular exhaust outlet adjacent thereto while 
other air is conveyed by the inner surfaces of the side walls 61 and 62 
and is compressed outwardly by the converging outer wall of the scroll, as 
is shown by the arrows in FIG. 7. Therefore, in this embodiment, a single 
scroll is utilized with a pair of spaced deflectors in order to distribute 
the exhaust air from the centrifugal fan generally uniformly radially 
outwardly with respect to the unit. 
The concept of utilizing spaced deflector walls with an annular outlet 
opening defined therebetween could be incorporated within the teachings of 
the invention which utilize two or more scrolls to direct the discharge of 
air from the air purifier.