Air cleaner

Herein disclosed is an air cleaner comprising: means defining an air passage, a plurality of corona discharge electrodes and a coupling discharge electrode arranged upstream of an air passage, being connected to a high voltage source for effecting a corona discharge downstream of the air passage for collecting the air-borne dust which has been charged by the corona discharge. The coupling discharge electrode is formed as a plate with a number of circular apertures therein, and each of the discharge electrodes has a multiplicity of leading ends shaped as sharp points arranged at the respective centers of the circular apertures and terminating generally on the plane thereof. The velocity of the air flow is increased in passage through the apertures to prevent the air cleaner from getting clogged. The corona discharge electrodes take the form of metal plates or bars extending generally rigidly across the air passage and mounted to the air cleaner at their ends, the sharp points being integral with the plates or bars and projecting therefrom toward the coupling electrode apertures.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention relates to an air cleaner for cleaning contaminated 
air by charging the dust floating in the air of an air passage with ions 
generated by a corona discharge to collect it by a dust collecting 
electrode and, more particularly, to an air cleaner which is enabled to 
have its dust collecting efficiency improved by making the corona 
discharge uniform and in which a discharge unit for the corona discharge 
is caused to get less clogged. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an air cleaner which is 
enabled to effectively solve all the above-specified defects. 
The air cleaner according to the present invention is characterized in that 
a coupling discharge electrode is made of a metallic plate having numerous 
holes to increase the flow velocity of air therethrough so that it may be 
prevented from getting clogged, and in that a discharge electrode is 
arranged at the respective centres of the holes of the coupling electrode.

DESCRIPTION OF THE PRIOR ART 
In a common house, an office, a gaming room, a chamber of the vehicle such 
as an automobile or a factory, an air cleaner is used for cleaning the 
surrounding air in the facilities. FIGS. 1 and 2 show examples of the air 
cleaner according to the prior art. In the air cleaner shown in FIG. 1, a 
coupling discharge electrode 2 made of a netted member is arranged in an 
air passage 1 at a right angle with respect to the air flow, and 
plate-shaped discharge and dust collecting electrodes 3 and 4 are arranged 
downstream of the passage 1 alterately of each other and in parallel with 
the air flow. In the air cleaner of FIG. 2, on the other hand, 
needle-shaped discharge electrodes 6 are arranged in cylindrical plates 5 
in which a coupling discharge electrode and dust collecting electrodes are 
integrated. However, the air cleaner of FIG. 1 has a defect that the 
meshes of the coupling discharge electrode 2 catch the dust to get 
clogged. On the other hand, the air cleaner of FIG. 2 has defects: that 
the dust collecting plates 5 are made of an assembly of cylinders and are 
difficult to be aligned with the discharge electrodes 6 so that charging 
irregularities are caused to degrade the dust collecting efficiency; and 
that the cylinder assembly has its effective area made so smaller than 
that of the air passage that it gets clogged when it is operated in the 
state of the irregular charge although it has a high air flow velocity. 
Moreover, the prior art has found it difficult to position and align the 
discharge electrodes. Stillmoreover, the discharge electrodes themselves 
are weak, and their replacements are troublesome. Furthermore, it is 
inconvenient to mount or demount the dust collecting electrodes having 
caught the dust. As the case may be, the deodorizing effect has been 
insufficient. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 3 to 7 are perspective views showing the whole structure of one 
embodiment of and sectional views showing the principles of the present 
invention. In a box-shaped casing 10, there is formed an air passage 11 in 
which air flows in a direction of arrow A. Upstream of this air passage 
11, there are arranged a pre-filter 12 made of a netted member and a 
discharge 20 for conducting a corona discharge. Downstream of the air 
passage 11, on the other hand, there are arranged a dust collector 30 for 
attracting and removing dust and a deodorizing filter 13. The 
aforementioned casing 10 can be either placed on a floor or hung from a 
wall or the like and has its upper end face formed with a suction port 16 
and its lower portion formed with a discharge port 14. By turning a fan 
(although not shown) such as a scirocco fan connected to a fan driver 15, 
the ambient air is caused to flow from the suction port 16 into the air 
passage 11 and is blown out from the discharge port 14. 
The aforementioned discharger 20 is constructed of a coupling discharge 
electrode 21 and a discharge electrode 22, between which the corona 
discharge is conducted. The discharge electrode 22 is made, as shown in 
FIG. 4, of a widthwise enlarged discharge plate 24 having its lower end 
edge formed integrally with a plurality of sharpened tips which protrude 
at a suitable spacing toward the coupling discharge electrode 21. That 
discharge electrode 22 is made of a conductive plate having a sufficient 
strength such as a plate of stainless steel, common steel, copper or brass 
having a thickness of 0.1 to 1.0 mm, preferably, 0.2 to 0.5 mm, and is 
prepared to have those sharp tips by pressing that plate. In this case, 
the discharge plate 22 can be shaped by the pressing work only if the 
plate thickness is about 1.0 mm. If the thickness exceeds 1 mm, it is 
necessary to improve the discharging effect by cutting the pressed tips. 
Moreover, that discharge plate 24 has both its end portions formed with 
raised tongues 24a at which it is held in a dust collecting unit 11' built 
in the aforementioned casing 10, as shown in FIG. 7. The discharge plate 
24 is electrically connected with a power supply 23 by having its end 
portions engaged with power supply connectors 17 which are formed at both 
the sides. The power supply may be alternatively used by converting the 
domestic A.C. power supply of 100 V into a high-voltage D.C. power supply 
of 4.5-5 KV and 0.1- 1 mA by a transformer. Moreover, the discharge plate 
24 has its central portion formed with a slot 24b which extends in the 
longitudinal direction thereof and which in turn is formed with a 
reinforcing rib 24 along its peripheral edge. A plurality of the discharge 
plates 24 thus prepared are so mounted to have their aforementioned raised 
tongues 24a connected with the power supply connectors 17 that they are 
arrayed in parallel with the air passage 11. The aforementioned discharge 
electrodes 22 are positioned at the centres of circular holes 21a which 
are formed in the coupling discharge electrode 21. As shown in FIG. 13, 
more specifically, the coupling discharge electrode 21 is made of a metal 
plate of an aluminum, copper or stainless alloy having a thickness of 0.5 
to 5 mm, which is formed with the numerous circular holes 21a, 21a and so 
on. These circular holes 21a can have their diameter suitably changed 
depending upon the discharging efficiency or the velocity of the air flow 
but may be commonly 20 to 40 mm. That metal plate is mounted in the air 
passage 11 at a right angle with respect to the same, and the 
aforementioned discharge electrodes 22 are positioned at the centres of 
the respective circular holes 21a of that coupling discharge electrode 21. 
This positioning at the centres of the circular holes makes uniform the 
corona discharge between the discharge electrode 22 and the coupling 
discharge electrode 21 thereby to eliminate the discharging 
irregularities. On the other hand, the total effective area of the 
circular holes 21a is smaller than the effective area of the air passage 
so that the air flow through the circular holes 21a takes a velocity 
sufficient for preventing the circular holes 21a from getting clogged. 
Now, the discharge electrode 22 can be also constructed as will be 
described with reference to FIGS. 9 to 12. 
In the embodiment of FIGS. 9 to 12, more specifically, the aforementioned 
discharge electrode 22 is constructed of: discharge needles 26, 26 and so 
on which have their leading ends protruding into the centers of the 
respective circular holes 21a, 21a and so on of the coupling discharge 
electrode 21; and holders 25, 25 and so on which hold those discharge 
needles 26, 26 and so on. Each of these discharge needles 26 is bent 
generally into the form of letter "C", as shown in FIG. 10. On the other 
hand, each of the holders 25 is made, as shown in FIG. 11, of an elongated 
rectangular bar which has both its sides formed with a plurality of 
engaging grooves 25a, 25a and so on at a suitable spacing. These engaging 
grooves 25a, 25a and so on are formed to fit and fix the aforementioned 
discharge needles 26 therein. In order to ensure these fitting actions, 
the widths or gaps of the discharge needles 26 are made slightly smaller 
than the thickness of the holder 25 so that the discharge needles 26 are 
held in the holder 25 by their own elasticities in their mounted states 
shown in FIG. 12. Moreover, the holders 25 have both their end portions 
protruding out of the passage 11 and suitably fixed on the frame of the 
air cleaner so that the discharge needles 26 have their leading ends 
positioned at the centers of the circular holes 21a of the aforementioned 
coupling discharge electrode 21 merely by fitting the discharge needles 26 
in those holders 25. 
Next, the aforementioned coupling discharge electrode 21 has both its end 
portions bent generally at a right angle downward, i.e., downstream of the 
air passage to form bent edges 21b which in turn have their lower ends 
formed with a plurality of parallel mounting grooves 27, 27 and so on. 
These mounting grooves 27, 27 and so on are used to fit therein dust 
collecting electrodes 31 which will be described hereinafter. On the other 
hand, FIG. 8B is a perspective view showing still another embodiment of 
the discharge plate which is indicated at 24'. A reinforcing plate 24d of 
stainless steel is spot-welded to that discharge plate 24' such that it 
extends in the longitudinal direction of the central portion thereof. 
On the other hand, the present invention can be constructed, as shown in 
FIG. 5. In FIG. 5, more specifically, an upstream air passage 20' arranged 
with the discharger 20 is intended to have a smaller effective area than 
that of a downstream air passage 30' arranged with the dust collector 30 
so that the air sucked flows at a higher velocity through the upstream 
passage 20' to effectively restrain the discharger 20 from getting clogged 
but at a lower velocity through the downstream passage 30' to improve the 
dust collecting efficiency. Incidentally, reference numeral 33 indicates a 
power supply which is connected with the respective dust collecting 
electrodes 31 and dust-collecting coupling electrodes 32 to establish an 
electric field inbetween. 
Next, the aforementioned dust collector 30 is arranged downstream of the 
discharger 20 thus formed to attract and remove the charged dust. As a 
result, the dust collector 30 has the plate-shaped dust collecting 
electrodes 31 and the plate-shaped dust-collecting coupling electrodes 32 
positioned alternatively such that they are arranged in parallel with the 
air flow through the air passage 11. With the power supply 23, moreover, 
there are connected the dust collecting electrodes 31 and the 
dust-collecting coupling electrodes 32, between which electric fields are 
generated to electrostatically attract the charged dust to the dust 
collecting electrodes 31 thereby to clean the air. Here, each of the 
aforementioned dust collecting electrodes 31 may be made of a metal plate 
but may be prepared by laminating aluminum foils on both the sides of a 
base plate of paper or by coating both the sides of the paper base plate 
with carbon. In short, the dust collecting electrode 31 may be made of a 
material having conductive surfaces. Moreover, a polyethylene film may be 
sandwiched between the base plate and the aluminum foils or the carbon 
coatings. This use of the paper base plate results in an effect that the 
dust collecting electrodes can be economically replaced by new ones in 
case their surfaces are contaminated with the dust. Those dust collecting 
electrodes 31 are removably attached by having both their end portions 
fitted in the mounting grooves 27 of the aforementioned coupling discharge 
electrode 21. As shown in FIG. 14, however, those mounting grooves 27 have 
their central portions curved generally in the form of letter "C" to form 
curved portions, which bite into the dust collecting electrode 21 fitted 
in the mounting grooves 27 so that the dust collecting electrodes 31 are 
fitted reliably and easily. As a result, the dust collecting electrodes 31 
can be replaced by new ones without any difficulty because they can be 
mounted requiring neither any screw nor any welding work and can be 
removed simply. For these fitting relationships, the mounting grooves may 
be molded to have another form such as corrugations. In FIG. 7: reference 
numeral 18 indicates a power supply connector for the coupling discharge 
electrode 21; numeral 19 indicates power supply connectors of the 
dust-collecting coupling electrodes 32 which are arranged in parallel with 
the dust collecting electrodes 31; and numeral 18' indicate an insulator 
for the former (and the dust collecting electrodes 31). Moreover, the dust 
collecting electrodes 31 and their coupling electrodes 32 are mounted by 
making use of guides 11" and 11" of an insulating material, which are 
mounted on the dust collecting unit 11'. 
Further downstream of such dust collector 30, there is disposed the 
deodorizing filter 13 for deodorizing the air, which is arranged at a 
right angle with respect to the air passage. That deodorizing filter 13 is 
charged with activated charcoal having an excellent deodorizing action to 
effect deodorization. This deodorizing agent need not be limited to the 
activated charcoal but may be an adsorbent of divalent iron ions or may be 
a mixture of the former two. In this case, the adsorbent of divalent iron 
ions may be exemplified by adding a small quantity of L-ascorbic acid to 
the divalent iron ions. This absorbent suppresses oxidization of the 
divalent iron ions into the oxygen in the air through reduction of the 
L-ascorbic acid so that its deodorization is maintained for a long time. 
Incidentally, reference numeral 10' appearing in FIG. 6 indicates a high 
power supply box in which the aforementioned power supply 23 is built to 
improve the corona discharge. 
The assembly of the air cleaner thus constructed is made by inserting the 
coupling discharge electrode 21 and the discharge plates 24 from one side 
of the body of the dust collecting unit 11' and holding them in the 
aforementioned positional relationship, by inserting the dust-collecting 
coupling electrodes 32 and the dust collecting electrodes 31 from the 
other side in parallel with one another by making use of the 
aforementioned guides 11", and by fitting both the end portions of the 
dust collecting electrodes 31 in the aforementioned mounting grooves 27 of 
the coupling discharge electrode 21, thus constructing the dust collecting 
unit 11'. Incidentally, reference numeral 11"' indicates a bail which is 
used to take in and out said unit. The dust collecting unit 11' thus 
constructed is mounted together with the pre-filter 12 and the deodorizing 
filter 13 in the casing 10. 
As has been described hereinbefore, according to the present invention, the 
coupling discharge electrode is made of the metal plate having the 
numerous circular holes, and the dischare electrodes have their leading 
ends positioned at the centres of the respective circular holes to 
eliminate the charging irregularities. Since the velocity of the air flow 
through the circular holes is high without any charging irregularity, 
moreover, the circular holes are reluctant to get clogged by the dust, and 
the bad smells such as cigarette smoke or ammonium gas can be filtered out 
together with the dust by the action of the deodorizing filter. 
Furthermore, the discharge electrodes can be easily assembled and 
positioned at the centres of those circular holes. 
Furthermore, the discharge electrodes and the coupling discharge electrode 
can be worked by the single pressing operation so that they can be molded 
with ease and at a reasonable cost. 
According to the present invention, furthermore, the dust collecting 
electrodes can be mounted and demounted with each so that their replacing 
works can be facilitated, and they are reluctant to come out once they are 
attached to the coupling discharge electrode so that the air cleaner is 
not troubled even if its casing is floated while it is being transported 
or installed. In case the dust collecting electrodes are formed by 
laminating the aluminum foils on the paper base plate or by coating the 
paper base plate with the carbon, they can be fabricated with ease and at 
a reasonable cost and can be disposed of so that they need not be washed 
to have their maintenance simplified.