Vacuum cleaning appliance

A vacuum cleaning appliance comprises a lower efficiency cyclone unit and a high efficiency cyclone unit connected in series. This enables both large and fine dirt particles to be dealt with.

DESCRIPTION 
This invention relates to a vacuum suction cleaning appliance and in 
particular to a portable domestic appliance of the kind described in the 
published EPC Specification No. 0 018 197. 
EPC Specification No. 0 018 197 describes an appliance in which a cleaner 
head for contacting a dirty surface is connected to the interior of the 
casing in which an airflow is set up by a motor driven fan. The casing 
contains two cyclone units in series operating successfully to extract 
dirt particles (dust and other extraneous matter) from the airflow 
therethrough and to deposit the extracted dirt. 
A cleaning appliance based on cyclone units has the advantage that dust 
bags are not required as dirt can be discharged from the appliance by 
removing and separating the cyclones from the surrounding casing. Other 
advantages are that the air discharged from the appliance is substantially 
dust free and the use of filters as main cleaning elements is avoided. 
In the appliance described in the said EPC patent application each of the 
two cyclone units has a body of substantially frusto-conical shape, this 
shape serving to maintain the velocity of the dirt particles swirling 
therein and hence render the cyclone capable of depositing fine dirt 
particles of small diameter. Such cyclone units with the means to maintain 
the velocity of the fine dirt particles will hereinafter be referred to as 
"high efficiency" cyclones. 
This invention recognises that a vacuum cleaner incorporating only the 
higher efficiency cyclones necessary to deal with the fine particles does 
not operate entirely satisfactorily under normal domestic conditions when 
dirt particles of larger size and other extraneous objects are sucked into 
the appliance. These larger size particles tend to be retained either 
performing the spiral or circular motion in the cyclone or drifting to the 
cyclone central regions and are not deposited. This causes noise and 
interferes with the efficient operation of the cyclone. 
Accordingly the present invention proposes incorporating into the air 
passage upstream, relatively to the inlet for dirty air, of the high 
efficiency cyclone unit a cyclone deliberately constructed to be of lower 
efficiency. 
The present invention relates to a vacuum cleaning appliance including a 
cyclone unit and means for generating an airflow from a dirty air inlet 
through the said cyclone unit the cyclone unit being of a high efficiency 
having the capability of depositing fine dust particles and the appliance 
being characterized by a lower efficiency cyclone unit in the air path 
upstream of the high efficiency unit. The present invention further 
relates to a vacuum cleaning appliance comprising a casing with a dirty 
air inlet at one end, a generally cylindrical body constituting the lower 
efficiency cyclone unit positioned within the casing and being connected 
to the dirty air inlet, the high efficiency cyclone having a 
frusto-conical body part and being positioned within the lower efficiency 
cyclone unit, air being caused to flow from the low to the high efficiency 
cyclone unit. 
This "lower efficiency" cyclone though not ultimately capable of dealing 
effectively with the finest particles, i.e., particles of 50 microns 
diameter or under, carries out a primary cleaning action of the dirty air 
flow by depositing all but some of these finer particles. The high 
efficiency cyclone is then left to function in its optimum conditions with 
comparatively clean air and only particles of very small size. 
The lower efficiency can be contrived by omitting the frusto-conical 
formation and constructing for example the cyclone casing of cylindrical 
form with the normal tangential or scroll type air inlet adjacent one end. 
Thus in a convenient and preferred configuration a vacuum cleaner casing 
comprises a generally cylindrical "low efficiency" cyclone with an inlet 
for dirty air and concentrically within the low efficiency cyclone a "high 
efficiency" cyclone, a passageway being provided to allow air from the low 
efficiency cyclone to enter an end part of the high efficiency cyclone. 
Clean air can then be withdrawn centrally from the high efficiency cyclone 
and exhausted if necessary through a final filter.

GENERAL DESCRIPTION 
The present invention relates to portable vacuum cleaning appliance 
comprising: 
(a) an outer cyclone comprising a bottom (13a) and a substantially 
cylindrical casing (13) extending to and meeting said bottom, said casing 
defining a substantially cylindrical interior surface which acts as a 
substantially constant cross-sectional dirt rotation surface for said 
outer cyclone throughout its length, a dirty air inlet (14) at an upper 
portion of the casing spaced from the bottom and oriented to supply dirt 
laden air tangentially to the interior surface, and an outer cyclone air 
outlet communicating with the interior of the outer cyclone; 
(b) an inner cyclone inside the outer cyclone having an upper end and a 
lower end smaller than the upper end and comprising an air inlet (18) 
oriented to supply air tangentially thereto and disposed at the upper end 
thereof in air communication through a passage (19) with the air outlet of 
the outer cyclone, the inner cyclone being of frusto-conical shape for 
maintaining the velocity of the air flow, and an inner cyclone air outlet 
communicating with the interior of the inner cyclone, the inner cyclone 
being separated from air flow connection with the outer cyclone except for 
the air inlet to the inner cyclone; 
(c) a vacuum cleaner casing (1) supporting the outer cyclone and mounted on 
wheels (9); 
(d) a floor contacting cleaning head (2) mounted on the vacuum cleaner 
casing including a brushing member (4) extending transversely of the head 
driven by a belt (5) attached to a shaft of a motor mounted on the vacuum 
cleaner casing adjacent the head; 
(e) a handle (6) mounted on the vacuum cleaner casing for moving the 
appliance across the floor; 
(f) an air entry means (11) providing an air flow path from the cleaning 
head adjacent the floor to the dirty air inlet at the upper portion of the 
outer cyclone; 
(g) an air exit means (21) providing a clean air flow path from the inner 
cyclone air outlet to the vacuum cleaner casing adjacent the cleaning 
head; and 
(h) fan means (3) driven by the motor for generating an air flow connected 
to the air exit means, wherein the air passes through the cleaning head, 
the air entry means, the dirty air inlet, the outer cyclone, the outer 
cyclone air outlet, the passage, the inner cyclone and the inner cyclone 
air outlet, the air exit means, the air flow rotating around the interior 
surface of the outer cyclone, the exterior of the inner cyclone and the 
interior of the inner cyclone, the outer cyclone being of lower efficiency 
in removing small particles of dirt from dirt laden air than the inner 
cyclone. 
SPECIFIC DESCRIPTION 
The cleaning appliance illustrated comprises a main casing 1 adapted for 
use both in the vertical mode and the horizontal mode, the vertical mode 
being illustrated. The functioning of the appliance will be described with 
reference to this vertical mode. At the lower end part of the casing a 
cleaning head 2 is provided, the head 2 comprising a motor driven fan unit 
3 and an elongate transversely extending brushing member 4 connected to 
the shaft of the motor by a belt 5. A pipe 6 stands upright along the back 
of the casing 1 and serves as a handle or for a connection to other 
suction tools. Extending between pipe 6 and to the upper end part of the 
casing is a holder for electric cable 7 and an on/off switch 8 for the 
appliance. The electrical arrangements for the cleaning appliance form no 
part of the present invention and will not be described. The appliance in 
the upright mode runs on wheels 9. 
Dirty air entering the appliance from behind brushes 4 communicates as can 
best be seen in FIG. 2 through a square port 10 with an entry passage 11 
for dirty air defined by a partcircular sleeve 12 within the casing (see 
FIG. 3). Centrally and coaxially within the casing 1 and slidably fitted 
in sleeve 12 is the cylindrical casing 13 of the first low efficiency 
cyclone unit. The upper end of the dirty air entrance passage 11 
communicates through part 14 providing an inlet 14a to casing 13 with the 
upper part of casing 13 so as to make a tangential entry and to set up a 
swirling cyclonic flow of air. 
The high efficiency cyclone unit comprises a frusto-conical body portion 15 
and a dependent cylindrical portion 16, the lower end part of which abuts 
against a support plate 17 on the base or bottom 13a of the low efficiency 
cyclone casing 13. Outside of the frusto-conical part and extending to a 
tangential entry port 18 is an entry pipe 19 to the high efficiency 
cyclone from the interior of the lower efficiency cyclone. The high 
efficiency cyclone unit is removable upwardly from the low efficiency 
cyclone unit and flexible bearing seals 20 are provided between the units. 
The upper end of the high efficiency cyclone communicates with a passage 
21 leading from inner cyclone outlet pipe or passage 18a at the side of 
the cleaner opposite to the dirty air entry passage and defined between 
sleeve 12 and the cleaner outer casing. The lower end part of this passage 
communicates through the motor fan to exhaust. 
The operation of the appliance will now be described with reference to the 
air flow designated by arrows differently marked to show the successive 
progress of the dirty air through the interior of the casing and the two 
cyclone units. .fwdarw.represents dirty air, .fwdarw.air cleaned by the 
low efficiency cyclone, .fwdarw.air cleaned by the high efficiency 
cyclone, and .fwdarw.finally discharged air. In operation of the device 
with the rotating brush 4 and the suction developed by the motor fan 3, 
dirty air carrying dust and other particles is drawn into the dirty air 
entry passage 11. The airstream carrying the dirt particles makes a 
tangential entry through port 14 into the upper part of the low efficiency 
cyclone casing 13 and performs cyclonic swirling movement generally along 
the line of the arrows and thereby deposits the majority of the dust 
particles in the lower part of the low efficiency cyclone as indicated at 
A. The airstream carrying only the finer particles then rises under the 
influence of the general airflow developed by the fan through pipe 19 and 
entry port 18 to a tangential entry to the high efficiency cyclone unit 
where the cyclonic cleaning process is repeated only with higher 
efficiency and greater particle velocity thereby contriving the deposit of 
the finer particles at B. The ultimately clean air rises under the 
influence of the air flow to the upper part of the high efficiency cyclone 
and returns through the clean air exit passage 21 to the motor fan and 
exhaust possibly with a final filter. 
For discharge of particles the lower and high efficiency cyclone casings 
are removed upwardly and disengaged from one another. It will be 
appreciated that when the high efficiency cyclone casing is lifted from 
its seating on the base of the low efficiency cyclone casing 13 the 
contents thereof will be deposited so that the cylindrical body holds all 
the deposited particles. If desired a disposable liner can be provided for 
the low efficiency cyclone casing. 
Means not shown may be provided for manually throttling the entry or exit 
pipe to the high efficiency cyclone. If the size of the entry or exit 
orifice to the cyclone is reduced then suction pressure is reduced but 
separation efficiency is enhanced. For use in the horizontal mode a valve 
schematically indicated at 22 is provided which is rotatable to close 
airflow from the brushes and to open the air passage to the pipe 6.