Portable air purge

The present invention provides a portable, motor driven air purifying instrument for purging impurities from the atmosphere about the user, i.e., from a more or less localized or confined body of air such as that in a room or in an automobile. It is designed to be used as a personal adjunct for purifying the atmosphere or body of air about a person with whom it is associated. It is designed for use indoors, i.e., in an enclosed or limited space.

BACKGROUND OF THE INVENTION 
There is need for a small, portable, power operated air purifier by persons 
suffering from respiratory ailments and/or allergies to airborne 
particulates such as dust, pollen, tobacco smoke, molds and so forth 
and/or to irritating or toxic gases such as ozone, sulfur dioxide, oxides 
of nitrogen, small amounts of carbon monoxide and others that occur in 
many city localities. Some of these offending substances are of sufficient 
public concern that daily advisories are supplied to the public by 
newspaper or television. 
The invention provides a means by which the user may set up and direct a 
stream or blanket of purified air to his face and to other parts of his 
person or into the room or other enclosure which he occupies. The device 
herein disclosed is highly desirable for use by a person traveling in an 
automobile and in particular in a vehicle such as an ambulance. 
In brief, two kinds of irritating or injurious substances are to be 
eliminated, namely irritating solids which permit elimination by 
filtration and gaseous irritants that can be eliminated only by adsorption 
of neutralization. 
For many individuals the so-called hay fever season brings with it 
breathing discomfort that makes the sufferer resort to such relief as he 
can obtain while virtually a prisoner in his own home. The alternative is 
to move to a location free of irritants. 
For many people breathing may be difficult the year around. This is 
particularly true in cities where in addition to ozone, pollen, bacteria, 
molds, spores, ragweed and the like, various chemical impurities foul the 
atmosphere, some of them continuously the year around. People with 
respiratory problems, young children, the elderly, and the ill are 
particularly affected. 
The air purifying device of the present invention is light in weight and 
readily portable. It cleanses the air through the purifying effect of a 
mechanical filter to take out particulate matter and in series therewith a 
bed of activated carbon which is capable of molecular activity and which 
eliminates virtually all of the common air pollutants including cigarette 
smoke and most of the ordinary unpleasant odors. Furthermore, it will 
reduce eye and throat irritation in many difficult situations. 
The air in our cities suffers from the presence of ozone, pollen grains, 
cigarette smoke, bacteria, molds, spores, ragweed, sulfur oxides, nitrogen 
oxides, hydro-carbon vapors and residues and other impurities for relief 
from which there is a present unsatisfied need. 
SUMMARY OF THE INVENTION 
The invention is advantageously embodied in a mall, portable, hand held air 
purifier, suitable to be operated by battery current of an automobile, for 
use in such a vehicle, and adapted for operation by house current for 
residential use. The device of the invention provides a small, compact, 
portable, power operated filter having a removal efficiency of 99.97% of 
airborne particulate matter of 0.3 micron size or larger. Under laboratory 
tests the filter of the present invention produces class 100 bio-clean air 
(not more than 100 particles of 0.5 micron in diameter or larger, per 
cubic foot of air). 
OBJECTS OF THE INVENTION 
The chief object of the present invention is to provide a small, portable, 
high efficiency air purifier unit suitable for personal use. The unit 
preferably is designed to be used on either A. C. or D. C. current, 
consuming about 40 watts. The D. C. model is particularly adaptable for 
use in motor vehicles by persons suffering from respiratory ailments 
and/or allergies. 
Another important object of the invention is to provide a device that in 
addition to being of high efficiency, is economical both in its initial 
cost and in its maintenance cost. 
It is a further object of the invention to make it easy for the operator to 
change the filtering and/or purifying components without requiring any 
special tools. The present invention aims further to provide a device 
which operates quietly with a gentle air flow (without turbulence) through 
the pre-filter, through a mass of fibrous material which serves as the 
particulate filter in a straight line of flow into and through a thick 
heavy bed of activated carbon that is held in compression by a pressure 
plate and coil spring. 
It is a further object to maintain a turbulence-free, gentle, flow of air 
through a bed of activated carbon without allowing the air to laminate 
along the container walls where it would escape the density and activity 
of the activated carbon bed. This is the purpose of the diffusion rings on 
the internal walls of the container, later referred to in detail, and also 
the reason for maintaining a uniform mechanical pressure over the entire 
bed of activated carbon. 
It is a further object to cause a smooth, turbulent-free flow of air in a 
straight line through the after filter of activated carbon and through the 
open center of the coil spring which holds the activated carbon compacted, 
into the center of the centrifugal impeller, to drive the air tangentially 
under pressure into the angularly adjustable rotatable scroll, and through 
a final filter for delivery to the adjacent atmosphere. 
Due to the larger pressure drop across the fibrous filter and the activated 
carbon bed, conventional type fans and propellers tend to allow too much 
slippage of air around the hub and fan tips from the pressure side to the 
suction side. This condition dilutes the delivered air with polluted air, 
thus reducing the overall efficiency of the air purifier. It is an object 
of the invention to avoid such contamination. In order to provide adequate 
adsorption of the toxic pollutants by the activated carbon definite limits 
have been set as to the velocity of air to which a particular bed of 
activated carbon can be subjected, in order to be effective. Previous 
inventions have limited their effectiveness to merely "de-odorizing" 
because of the large volume (200-400 cubic feet per minute) through a thin 
panel of loosely held activated carbon (see Mason U.S. Pat. No. 
3,936,284). Air is not purified to an extent required to make it fit for 
human breathing by taking out only airborne particulates and yet allowing 
toxic gases to pass through or vice-versa. The removal of toxic gases is 
by far the most difficult to effect on an economical portable basis, and 
in this respect the present invention is highly advantageous.

DETAILED DESCRIPTION OF THE DRAWINGS 
The portable air purifier herein disclosed and claimed comprises an outer 
molded two-part longitudinally divided cylindrical shell 24-25 into the 
open left hand end of which (see FIG. 1) there is inserted a short 
cylindrical molded plastic split sleeve 4 the outer end of which has a 
bell flange 4a in which is sealed an inlet screen 1 which is held therein 
by friction and which is readily removable. The screen 1 has a cylindrical 
flange which extends toward and fits inside of the sleeve 4 of the shell 
24 and said flanged screen is filled with the pre-filter 2 consisting of a 
pad of spun fiber glass or similar inert, synthetic material. The 
pre-filter 2 is retained by friction within the offset flange 4a of the 
two-part split cylindrical container 4 which is held by friction in the 
open end of the main two-part cylindrical shell 24-25. The pre-filter unit 
consists of the screen 1 and the pre-filter pad 2 which is made of spun 
fiber glass and is seated in the annular recess of flange 4a of the cup 
shaped high efficiency filter shell 24 which is constructed of two 
matching halves split longitudinally. These matching halves of the shell 
24 embrace the contained mass of high efficiency particulate air filter 
adsorbent material 8 consisting of a folded webb of woven fiber which is 
efficient for removing particulates of 0.3 micron or larger. The fiber 
material preferably is made of spun glass. 
These two longitudinally extending semi-cylindrical filter shell parts 4,4 
are embraced by the adjacent ends of the outer main shell parts 24,25 
consisting of the two matching half tubes having their edges joined at an 
offset split surface on each side extending longitudinally as shown at the 
top and at the bottom of FIG. 3. The meeting edges of these two main 
semi-cylindrical shell parts 24,25 are held together at the overlapping 
joints 4--4 at the top and bottom of FIG. 1, by the cylindrical embracing 
bands 5--5. The bands 5--5 which hold the casing halves 24,25 together, in 
alignment carry integrally formed buttons 30 and 31 which are embraced by 
suitable eyes in the ends of a carrying strap 23 for carrying and handling 
the unit. This strap constitutes not only a convenient carrying means but 
serves to orient, in a favorable manner the location of the screened 
outlet 21 with the discharge of filtered air in an upward direction when 
the unit is in the position shown in FIG. 1. 
The discharge outlet 21 of the snail shell or scroll shaped casing 13 which 
embraces and is mounted peripherally about the two casing halves has 
cylindrical flanges 33,34 embracing the main tubular shell 24, 25 and is 
rotatable thereon to bring the screened outlet 21 into any angular 
position around the longitudinal axis of the device. The user may select 
the direction of the discharge. The expansible locking ring 26 in the 
groove 35 maintains the screen frame 6 against axial displacement. 
The opposite end of the body of activated carbon 8 is engaged by a screen 
7a mounted in a circular frame 9 which carries screen 7a, is guided for 
sliding movement, on the inside of the main casing, and occupying the 
cross-section of the same. A compression spring 11 rests against the outer 
edge of the screen carrying ring 9, and at its other end presses against 
an annular flange or spring anchor 32 to hold the granular activated 
carbon in compression between screens 7 and 7a at all times. 
The body of activated carbon 8 should be held in undisturbed condition to 
gain its maximum beneficial effect. It is to be noted that in the 
operation of the device, air is drawn through the body of activated carbon 
against the pressure of the spring 11 and its screen 7a to avoid the 
packing effect which will be produced by having the spring pressure and 
the suction effect of the bore work in the same direction. 
The shell is perforated by a pair of peripherally disposed openings 26a in 
a plane transverse to the axial line of the casing shell. These 
perforations are provided for the insertion of holding pins (not shown) 
that are inserted to overhang the top of the screen ring 9 to provide room 
for a fresh filling of activated carbon, when the spent carbon is removed. 
The main casing sections or matching halves 25 are provided on their inner 
peripheries with annular radially inwardly extending ribs 41 serving the 
purpose of interrupting any channeling which might tend to form and permit 
air leakage between the inside surface of the containing shell and the 
body of activated carbon particles. 
The two main shell halves are held in circumferential register along their 
longitudinal edges by the interrupted or offset radial joints at their 
meeting edge. These edges are held against displacement radially and 
circumferentially by the encircling bands 5-5a which embrace the 
cylindrical surfaces in a radial direction and engage endwise the annular 
radially extending rings 35a-34 adjacent the discharge end of the device. 
A similar band 5a at the right hand end in FIG. 1 performs like service of 
holding the casing halves firmly together. Each of these bands 5 and 5a 
carries a button 30 and 31 extending radially from the casing. The 
carrying strap 23 has eyes at its end which eyes receive the shank of the 
button at each end to form a handle and carrying strap. Since the outlet 
from the discharge volute is rotatable about the axis of the cylindrical 
body the angular location of the carrying strap may remain fixed. 
The snail shell shaped air discharge fitting or scroll 13 embraces and is 
co-axial with and rotatable on the cylindrical shell of the device. Within 
the main cylindrical shell 24-25 at the right hand end of the shell, as 
shown in FIG. 1, the blower motor 16 is mounted as by means of the screws 
14--14 upon the circular mounting plate 15 (see FIG. 1). The closure and 
mounting switch plate 19 is perforated to provide cooling openings 19a, 
19a for air cooling the motor 16. The frame of the motor 16 is mounted at 
its left hand end as viewed in FIG. 1 upon the transverse plate 15 of 
circular outline, the peripheral edge of which fits within the adjacent 
end portion of the cylindrical shell, 4 being held in a groove 15a formed 
in the insides of the two casing parts. The rotatable shaft 16a of the 
motor enters the hub 12 of the centrifugal impeller 37 which has radially 
short involute fan blades 37a between the front and the back plates of the 
impeller. The blades are designed to produce a substantial tangential 
pressure. The rotatable shaft 35 of the motor enters and is held in the 
hub 12 of the centrifugal impeller 37 which has approximately involute fan 
blades of short radial length, said fan blades being disposed in axial 
parallelism between the front and back plates of the impeller. The space 
between the blades is open radially inwardly towards the center for the 
admission of air entering from the filter bed 8 through the end screen 7a 
and outwardly into the volute 13 as indicated by the arrows in FIG. 2. The 
frame of the motor 16 is mounted upon the transverse plate 15 of circular 
outline. Said plate 15 fits within a groove formed on the inside wall of 
the adjacent end portions of the main cylindrical shell (two-part) 24-25. 
The screen 7a is pressed against the activated carbon filter by the spring 
11 (as shown in FIGS. 1 and 2). 
The discharge of air peripherally from the impeller is conducted in a 
spiral outwardly expanding path through expanding involute shaped duct 13 
which projects from the sidewall of the instrument. The outer end of the 
discharge duct 13 is covered by a guard screen 21 of open mesh. 
The scroll or involute shaped discharge fitting 13 has its ends extended in 
an axial direction with respect to the main casing my means of cylindrical 
flanges 33 and 34 which embrace the cylindrical shell between annular 
shoulders on the shell and the band 5a. The operator may, by rotating the 
scroll 13, (see FIG. 2) reduce the circumferential dimension of the 
opening between the discharging blades of the impeller and the freedom of 
passage of the discharge air through the outlet thereby restricting the 
volume of the discharge of air from the appliance. 
Replacing of the spent filtering material may be effected as follows: the 
molded inlet screen 1 may readily by pulled out of the cylindrical seat in 
the flange 4a where it is held merely by friction. The pre-filter 2 of 
spun fiber glass or the like synthetic material may be replaced. The 
supporting ring 26 may be contracted (see FIG. 4) and be removed from the 
groove in which it is seated by pressing the two end 27--27 (shown in FIG. 
4) towards each other and removed from the casing. Thereupon the molded 
plastic screen retainer ring 6 which has four bayonet slots cooperating 
with stationary pins, may be released and removed. The central portion of 
the mass 8 of activated carbon may be depressed against the spring 11 and 
turned angularly to release the bayonet slot connection between said ring 
6 and the stationary pins 29 and be withdrawn from the casing. 
Thereupon the granular activated carbon 8 which is regarded as spent 
material may be discarded. 
Then before a fresh charge of activated carbon is introduced the pressure 
plate or ring 9 is pushed down against the spring 11, and pins which may 
be furnished as part of the equipment, or nails may be inserted into holes 
on each side of the main casing as shown in FIG. 1. They are inserted in 
the openings 26--26 in the walls of the shell. 
After depressing the ring or pressure plate 9 against the coil spring 11 
insert a pin or nail through each of the two or three holes 26 in the side 
walls to hold the ring or plate 9 in compressed position to make room for 
the charge of activated carbon 8 which is then poured into the interior of 
the casing to rest upon the screen 7a carried as part of the pressure 
plate 9. 
Before introducing a fresh charge of activated carbon, the circular wire 
screen 7a is set in the annular pressure plate 9. Preferably, a disk (not 
shown) of fibrous after-filter may be laid upon the ring 10 before laying 
the wire screen 7a to serve as an after-filter to catch any solid 
particles which may have been released by the activated carbon in the 
course of performing its service. After the filling of activated carbon is 
introduced the screen frame 6 (at the left of FIG. 1) is pressed down on 
the filling of activated carbon and is locked in place by being depressed 
against spring 11 and rotated to bring the pin 29 into locking engagement 
in the bayonet slot 28--28 in the side wall of the container. 
Thereupon the locking ring 26 is contracted by pinching the radial ends 
27--27 towards each other. The ring is then introduced into the groove 35 
and released thereby locking the screen ring 6 and its screen 7 in place 
in the barrell of the instrument. 
Inwardly extending permanent annular ridges 41--41 are formed on the inner 
walls of the casing sections in matching relation to reduce the likelihood 
of there being a longitudinally extending gap between the filling of 
activated carbon and the inner walls of the shell. These rings 41--41 
provide a safeguard against leakage, which would by-pass filtration 
through the activated carbon bed. The mass of activated carbon particles 
is under constant spring pressure imposed by the compression spring 11 to 
press the activated particles against each other and against the 
containing walls in all directions. 
The expansible locking ring 26 shown in FIGS. 1 and 4 which may be 
contracted by pressure upon the finger pieces 27--27 is introduced into 
the groove 26 in the outer shell and allowed to expand and thereby lock 
the screen holding ring 6 and its screen 7 in position to restrain the 
compressed activated carbon granuals between the two screens, namely 
between the outer screen 7 and the inner screen 7a. 
The cricumferential band 5 at the left of FIG. 1 holds the two parts of the 
shell together in alignment at the front end of the main body and a 
similar band 5a embraces the two halves of the body adjacent the scroll 
13. These bands 5--5a connected by the strap 23. 
The cylindrical shell 4 which contains the high efficiency particulate 
filter of spun glass or the like is held frictionally in the outer end of 
the main shell 24 under light pressure by its own resilience. The entry 
screen 1 with the spun fiber glass pre-filter 2 is held frictionally in 
the outer flange 4a and it may be withdrawn and the fiber filter replaced 
and the parts assembled in the position shown in FIG. 1. 
OPERATION OF THE UNIT 
The holding strap 23 being attached to the pins 31-30, the unit may be put 
into operation, held suspended, or it may be laid on its side or set on 
its end. The discharge volute 13 with the screened outlet 21 is rotatable 
on the main body of the device to bring the discharge outlet into any 
desired angular position. As is above pointed out and as is apparent from 
FIG. 2 the outlet from the impeller may be restricted from the maximum 
open position shown in FIG. 2 to a minimum discharge open position when 
the volute 13 is rotated to a maximum restriction corresponding to a 
90.degree. turn of the discharge volute 13 from the position shown in FIG. 
2 in a counterclockwise direction. The impeller is driven in the clockwise 
direction as viewed in FIG. 2 to throw the air tangentially as indicated 
by the arrows on FIG. 2. 
The outlet screen 21 is not intended to act as a dust separator although it 
may to some extent perform that service, but is intended primarily to 
prevent the accidential insertion of an article into the volute, from 
which it might accidentally come into contact with the impeller.