U.S. patent application number 16/637887 was filed with the patent office on 2020-05-28 for dirt separator for a vacuum cleaner.
This patent application is currently assigned to Dyson Technology Limited. The applicant listed for this patent is Dyson Technology Limited. Invention is credited to Alexander Michael CAMPBELL-HILL, Charles Howard PERCY-RAINE.
Application Number | 20200163508 16/637887 |
Document ID | / |
Family ID | 59896012 |
Filed Date | 2020-05-28 |
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United States Patent
Application |
20200163508 |
Kind Code |
A1 |
PERCY-RAINE; Charles Howard ;
et al. |
May 28, 2020 |
DIRT SEPARATOR FOR A VACUUM CLEANER
Abstract
A dirt separator for a vacuum cleaner includes: a chamber within
which dirt separated by the dirt separator collects, a duct that
extends within the chamber; and a flange that extends outwardly
from the duct. The chamber is delimited by a bottom wall and a side
wall. The bottom wall is moveable relative to the side wall between
an open position and a closed position. The duct is attached to and
moveable with the bottom wall, and at least a part of the flange is
flexible.
Inventors: |
PERCY-RAINE; Charles Howard;
(Swindon, GB) ; CAMPBELL-HILL; Alexander Michael;
(Gloucester, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dyson Technology Limited |
Wiltshire |
|
GB |
|
|
Assignee: |
Dyson Technology Limited
Wiltshire
GB
|
Family ID: |
59896012 |
Appl. No.: |
16/637887 |
Filed: |
July 27, 2018 |
PCT Filed: |
July 27, 2018 |
PCT NO: |
PCT/GB2018/052148 |
371 Date: |
February 10, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A47L 9/1409 20130101;
A47L 9/149 20130101; A47L 9/1683 20130101; A47L 9/102 20130101;
A47L 9/1658 20130101 |
International
Class: |
A47L 9/14 20060101
A47L009/14; A47L 9/10 20060101 A47L009/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 11, 2017 |
GB |
1712938.8 |
Claims
1. A dirt separator for a vacuum cleaner, the dirt separator
comprising: a chamber within which dirt separated by the dirt
separator collects; a duct that extends within the chamber; and a
flange that extends outwardly from the duct, wherein the chamber is
delimited by a bottom wall and a side wall, the bottom wall is
moveable relative to the side wall between an open position and a
closed position, the duct is attached to and moveable with the
bottom wall, and at least a part of the flange is flexible.
2. The dirt separator of claim 1, wherein the flange contacts the
side wall and flexes when the bottom wall moves between the open
position and the closed position.
3. The dirt separator of claim 1, wherein the bottom wall pivots
relative to the side wall when moving between the open position and
the closed position.
4. The dirt separator of claim 1, wherein the duct extends linearly
within the chamber.
5. The dirt separator of claim 1, wherein the duct comprises an end
through which dirt-laden fluid enters the chamber, the duct extends
upwardly from the bottom wall, and the flange is located at or
adjacent the end of the duct.
6. The dirt separator of claim 1, wherein the duct extends through
the bottom wall, and an end of the duct is attachable to different
attachments of the vacuum cleaner.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a national stage application under 35
USC 371 of International Application No. PCT/GB2018/052148, filed
Jul. 27, 2018, which claims the priority of United Kingdom
Application No. 1712938.8, filed Aug. 11, 2017, the entire contents
of each of which are incorporated herein by reference.
FIELD OF THE DISCLOSURE
[0002] The present invention relates to a dirt separator for a
vacuum cleaner.
BACKGROUND OF THE DISCLOSURE
[0003] The dirt separator of a vacuum cleaner may comprise a
chamber that is partitioned in two by a plate. A first part of the
chamber may then be used as an area within which dirt is separated
from a fluid, and a second part of the chamber may be used to
collect the separated dirt. The partition plate then hampers dirt
collected in the second part of the chamber being re-entrained by
the fluid in the first part of the chamber. A problem with this
arrangement, however, is that the partition plate often makes
emptying of the chamber difficult.
SUMMARY OF THE DISCLOSURE
[0004] According to various aspects, the present invention provides
a dirt separator for a vacuum cleaner, the dirt separator
comprising: a chamber within which dirt separated by the dirt
separator collects; a duct that extends within the chamber; and a
flange that extends outwardly from the duct, wherein the chamber is
delimited by a bottom wall and a side wall, the bottom wall is
moveable relative to the side wall between an open position and a
closed position, the duct is attached to and moveable with the
bottom wall, and at least a part of the flange is flexible.
[0005] Having a wall that moves between open and closed positions
simplifies emptying of the dirt separator. The flange, which
extends outwardly from the duct, helps to reduce re-entrainment of
dirt within the chamber. The duct provides a number of functions.
As well as carrying fluid to or from the chamber, the duct acts to
support the flange within the chamber. Consequently, in contrast to
existing dirt separators having a partition plate, the dirt
separator does not require an additional support element to hold
the flange at the appropriate position within the chamber. The duct
is attached to and is moveable with the bottom wall. This then
helps encourage dirt emptying when the bottom wall moves to the
open position. For example, when the bottom wall moves to the open
position, the moving duct may push or pull dirt out of the
chamber.
[0006] During use, dirt that collects within the chamber may become
compressed and apply a downward force on the flange. If the flange
were wholly rigid, the force would be transferred to the bottom
wall, which may then move relative to the side wall when in the
closed position. As a result, the mechanism used to retain the
bottom wall in the closed position may be more difficult to
release. However, rather than being wholly rigid, at least part of
the flange is flexible. As a result, any downward force applied to
the flange will cause that part of the flange to flex downwards. As
a result, movement of the bottom wall is reduced, thus making it
easier to release the bottom wall from the closed position.
[0007] The flange may contact the side wall and flex when the
bottom wall moves between the open position and the closed
position. This then has the advantage that a relatively wide flange
may be employed, thereby reducing dirt re-entrainment, whilst still
allowing the bottom wall to move between the open and closed
positions.
[0008] The bottom wall may pivot relative to the side wall when
moving between the open position and the closed position. This then
has the advantage that the bottom wall remains attached to the dirt
separator when moving between the open and closed positions, thus
simplifying emptying of the dirt separator.
[0009] The duct may extend linearly within the chamber. This then
has the advantage that fluid moves through the duct along a
straight path, thereby reducing pressure losses.
[0010] The duct may comprise an end through which dirt-laden fluid
enters the chamber, the duct may then extend upwardly from the
bottom wall, and the flange may be located at or adjacent the end
of the duct. Dirt-laden fluid is then introduced into the portion
of the chamber located above the flange, whilst dirt separated from
the fluid collects in the portion of the chamber located below the
flange. As a result, dirt re-entrainment may be reduced. Since the
bottom wall is moveable between open and closed positions, the dirt
collected below the flange can be conveniently removed.
[0011] The duct may extend through the bottom wall, and an end of
the duct may be attachable to different attachments of the vacuum
cleaner. In particular, the duct may be attachable to different
accessory tools of the vacuum cleaner. By providing a duct to which
different attachments may be directly attached, a relatively short
path may be provided between the different attachments and the dirt
separator. As a result, pressure losses may be reduced.
BRIEF DESCRIPTION OF THE FIGURES
[0012] In order that the present invention may be more readily
understood, embodiments of the invention will now be described, by
way of example, with reference to the accompanying drawings in
which:
[0013] FIG. 1 is a perspective view of a vacuum cleaner;
[0014] FIG. 2 is a section through a part of the vacuum
cleaner;
[0015] FIG. 3 is a section through a dirt separator of the vacuum
cleaner;
[0016] FIG. 4 is a plan view of a disc of the dirt separator;
[0017] FIG. 5 illustrates the flow of dirt-laden fluid through the
dirt separator;
[0018] FIG. 6 illustrates emptying of the dirt separator;
[0019] FIG. 7 is a section through a part of the vacuum cleaner
when used for above-floor cleaning;
[0020] FIG. 8 is a section through a part of a vacuum cleaner
having a first alternative dirt separator;
[0021] FIG. 9 is a section through a second alternative dirt
separator;
[0022] FIG. 10 is a section through a third alternative dirt
separator;
[0023] FIG. 11 is a perspective view of a flange and part of an
inlet duct of the third alternative dirt separator;
[0024] FIG. 12 illustrates emptying of the third alternative dirt
separator; and
[0025] FIG. 13 illustrates an alternative disc assembly that may
form part of any one of the dirt separators.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0026] The vacuum cleaner 1 of FIG. 1 comprises a handheld unit 2
attached to a cleaner head 4 by means of an elongate tube 3. The
elongate tube 3 is detachable from the handheld unit 2 such that
the handheld unit 2 may be used as a standalone vacuum cleaner.
[0027] Referring now to FIGS. 2 to 7, the handheld unit 2 comprises
a dirt separator 10, a pre-motor filter 11, a vacuum motor 12 and a
post-motor filter 13. The pre-motor filter 11 is located downstream
of the dirt separator 10 but upstream of the vacuum motor 12, and
the post-motor filter 13 is located downstream of the vacuum motor
12. During use, the vacuum motor 12 causes dirt-laden fluid to be
drawn in through a suction opening in the underside of the cleaner
head 4. From the cleaner head 4, the dirt-laden fluid is drawn
along the elongate tube 3 and into the dirt separator 10. Dirt is
then separated from the fluid and retained within the dirt
separator 10. The cleansed fluid exits the dirt separator 10 and is
drawn through the pre-motor filter 11, which removes residual dirt
from the fluid before passing through the vacuum motor 12. Finally,
the fluid expelled by the vacuum motor 12 passes through the
post-motor filter 13 and is exhausted from the vacuum cleaner 1 via
vents 14 in the handheld unit 2.
[0028] The dirt separator comprises a container 20, an inlet duct
21, and a disc assembly 22.
[0029] The container 20 comprises a top wall 30, a side wall 31,
and a bottom wall 32 that collectively define a chamber 36. An
opening in the centre of the top wall defines an outlet 38 of the
chamber 36. The bottom wall 32 is attached to the side wall 31 by
means of a hinge 33. A catch 34 attached to the bottom wall 32
engages with a recess in the side wall 31 to hold the bottom wall
32 in a closed position. Releasing the catch 34 then causes the
bottom wall 32 to swing to an open position, as illustrated in FIG.
6.
[0030] The inlet duct 21 extends upwardly through the bottom wall
32 of the container 20. The inlet duct 21 extends centrally within
the chamber 36 and terminates a short distance from the disc
assembly 22. One end of the inlet duct 21 defines an inlet 37 of
the chamber 36. The opposite end of the inlet duct 21 is attachable
to the elongate tube 3 or an accessory tool when the handheld unit
2 is used as a standalone cleaner.
[0031] The disc assembly 22 comprises a disc 40 coupled to an
electric motor 41. The electric motor 41 is located outside of the
chamber 36, and the disc 40 is located at and covers the outlet 38
of the chamber 36. When powered on, the electric motor 41 causes
the disc 40 to rotate about a rotational axis 48. The disc 40 is
formed of a metal and comprises a central non-perforated region 45
surrounded by a perforated region 46. The periphery of the disc 40
overlies the top wall 30 of the container 20. As the disc 40
rotates, the periphery of the disc 40 contacts and forms a seal
with the top wall 30. In order to reduce friction between the disc
40 and the top wall 30, a ring of low-friction material (e.g. PTFE)
may be provided around the top wall 30.
[0032] During use, the vacuum motor 12 causes dirt-laden fluid to
be drawn into the chamber 36 via the inlet 37. The inlet duct 21
extends centrally within the chamber 36 along an axis that is
coincident with the rotational axis 48 of the disc 40. As a result,
the dirt-laden fluid enters the chamber 36 in an axial direction
(i.e. in a direction parallel to the rotational axis 48). Moreover,
the dirt-laden fluid is directed at the centre of the disc 40. The
central non-perforated region of the disc 40 causes the dirt-laden
fluid to turn and move radially outward (i.e. in a direction normal
to the rotational axis). The rotating disc 40 imparts tangential
forces to the dirt-laden fluid, causing the fluid to swirl. As the
dirt-laden fluid moves radially outward, the tangential forces
imparted by the disc 40 increase. Upon reaching the perforated
region 46 of the disc 40, the fluid is drawn axially through the
holes 47 in the disc 40. This requires a further turn in the
direction of the fluid. The inertia of the larger and heavier dirt
is too great to allow the dirt to follow the fluid. As a result,
rather than being drawn through the holes 47, the dirt continues to
move radially outwards and eventually collects at the bottom of the
chamber 36. Smaller and lighter dirt may follow the fluid through
the disc 40. The bulk of this dirt is then subsequently removed by
the pre-motor and post-motor filters 11,13. In order to empty the
dirt separator 10, the catch 34 is released and the bottom wall 32
of the container 20 swings open. As illustrated in FIG. 6, the
container 20 and the inlet duct 21 are configured such that the
inlet duct 21 does not prevent or otherwise hinder the movement of
the bottom wall 32.
[0033] In addition to cleaning floor surfaces, the vacuum cleaner 1
may be used to clean above-floor surfaces such as shelves, curtains
or ceilings. When cleaning these surfaces, the handheld unit 2 may
be inverted as shown in FIG. 7. Dirt 50 collected in the chamber 36
may then fall down towards the disc 40. Any dirt falling onto the
disc 40 is likely to be drawn through or block some of the holes 47
in the perforated region 46. As a result, the available open area
of the disc 40 will decrease and the speed of the fluid moving
axially through the disc 40 will increase. More dirt is then likely
to be carried by the fluid through the disc 40 and thus the
separation efficiency of the dirt separator 10 is likely to
decrease. The top wall 30 of the container 20 is not flat but is
instead stepped. As a result, the chamber 36 comprises a gulley
located between the side wall 31 and the step in the top wall 30.
This gulley surrounds the disc 40 and acts to collect dirt 50 that
falls down the chamber 36. As a result, less dirt is likely to fall
onto the disc 40 when the handheld unit 2 is inverted.
[0034] The dirt separator 10 has several advantages over a
conventional separator that employs a porous bag. The pores of a
bag quickly clog with dirt during use. This then reduces the
suction that is achieved at the cleaner head. Additionally, the bag
must normally be replaced when full, and it is not always easy to
determine when the bag is full. With the dirt separator described
herein, rotation of the disc 40 ensures that the holes 47 in the
perforated region 46 are generally kept clear of dirt. As a result,
no significant reduction in suction is observed during use.
Additionally, the dirt separator 10 may be emptied by opening the
bottom wall 32 of the container 20, thus avoiding the need for
replacement bags. Furthermore, by employing a transparent material
for the side wall 31 of the container 20, a user is able to
determine with relative ease when the dirt separator 10 is full and
requires emptying. The aforementioned disadvantages of a porous bag
are well known and are solved equally well by a separator that
employs cyclonic separation. However, the dirt separator 10
described herein also has advantages over a cyclonic separator.
[0035] In order to achieve a relatively high separation efficiency,
the cyclonic separator of a vacuum cleaner typically comprises two
or more stages of separation. The first stage often comprises a
single, relatively large cyclone chamber for removing coarse dirt,
and the second stage comprises a number of relatively small cyclone
chambers for removing fine dirt. As a result, the overall size of
the cyclonic separator can be relatively large. A further
difficulty with the cyclonic separator is that it requires high
fluid speeds in order to achieve high separation efficiencies.
Furthermore, the fluid moving through the cyclonic separator often
follows a relatively long path as it travels from the inlet to the
outlet. The long path and high speeds result in high aerodynamic
losses. As a result, the pressure drop associated with the cyclonic
separator can be high. With the dirt separator described herein,
relatively high separation efficiencies can be achieved in a more
compact manner In particular, the dirt separator comprises a single
stage having a single chamber. Furthermore, separation occurs
primarily as a result of the angular momentum imparted to the
dirt-laden fluid by the rotating disc 40. As a result, relatively
high separation efficiencies can be achieved at relatively low
fluid speeds. Additionally, the path taken by the fluid in moving
from the inlet 37 to the outlet 38 of the dirt separator 10 is
comparatively short. As a consequence of the lower fluid speeds and
shorter path, aerodynamic losses are smaller. As a result, the
pressure drop across the dirt separator 10 is smaller than that
across the cyclonic separator, for the same separation efficiency.
The vacuum cleaner 1 is therefore able to achieve the same cleaning
performance as that of a cyclonic vacuum cleaner using a less
powerful vacuum motor. This is particularly important should the
vacuum cleaner 1 be powered by a battery, since any reduction in
the power consumption of the vacuum motor 11 may be used to
increase the runtime of the vacuum cleaner 1.
[0036] The provision of a rotating disc within a dirt separator of
a vacuum cleaner is known. For example, DE19637431 and U.S. Pat.
No. 4,382,804 each describe a dirt separator having a rotating
disc. However, there is an existing prejudice that the dirt
separator must include a cyclone chamber to separate the dirt from
the fluid. The disc is then used merely as an auxiliary filter to
remove residual dirt from the fluid as it exits the cyclone
chamber. There is a further prejudice that the rotating disc must
be protected from the bulk of the dirt that enters the cyclone
chamber. The dirt-laden fluid is therefore introduced into the
cyclone chamber in a manner that avoids direct collision with the
disc.
[0037] The dirt separator described herein exploits the finding
that dirt separation may be achieved with a rotating disc without
the need for a cyclone chamber. The dirt separator further exploits
the finding that effective dirt separation may be achieved by
introducing the dirt-laden fluid into a chamber in a direction
directly towards the disc. By directing the dirt-laden fluid at the
disc, the dirt is subjected to relatively high forces upon contact
with the rotating disc. Dirt within the fluid is then thrown
radially outward whilst the fluid passes axially through the holes
in the disc. As a result, effective dirt separation is achieved
without the need for cyclonic flow.
[0038] The separation efficiency of the dirt separator 10 and the
pressure drop across the dirt separator 10 are sensitive to the
size of the holes 47 in the disc 40. For a given total open area,
the separation efficiency of the dirt separator 10 increases as the
hole size decreases. However, the pressure drop across the dirt
separator 10 also increases as the hole size decreases. The
separation efficiency and the pressure drop are also sensitive to
the total open area of the disc 40. In particular, as the total
open area increases, the axial speed of the fluid moving through
the disc 40 decreases. As a result, the separation efficiency
increases and the pressure drop decreases. It is therefore
advantageous to have a large total open area. However, increasing
the total open area of the disc 40 is not without its difficulties.
For example, as already noted, increasing the size of the holes in
order to increase the total open area may actually decrease the
separation efficiency. As an alternative, the total open area may
be increased by increasing the size of the perforated region 46.
This may be achieved by increasing the size of the disc 40 or by
decreasing the size of the non-perforated region 45. However, each
of these options has its disadvantages. For example, since a
contact seal is formed between the periphery of the disc 40 and the
top wall 30, more power will be required to drive a disc 40 having
a larger diameter. Additionally, a rotating disc 40 of larger
diameter may generate more stirring within the chamber 36. As a
result, re-entrainment of dirt already collected in the chamber 36
may increase and thus there may actually be a net decrease in the
separation efficiency. On the other hand, if the diameter of the
non-perforated region 45 were decreased then, for reasons detailed
below, the axial speed of the fluid moving through the disc 40 may
actually increase. Another way of increasing the total open area of
the disc 40 is to decrease the land between the holes 47. However,
decreasing the land has its own difficulties. For example, the
stiffness of the disc 40 is likely to decrease and the perforated
region 46 is likely to become more fragile and thus more
susceptible to damage. Additionally, decreasing the land between
holes may introduce manufacturing difficulties. There are therefore
many factors to consider in the design of the disc 40.
[0039] The disc 40 comprises a central non-perforated region 45
surrounded by a perforated region 46. The provision of a central
non-perforated region 45 has several advantages, which will now be
described.
[0040] The stiffness of the disc 40 may be important in achieving
an effective contact seal between the disc 40 and the top wall 30
of the container 20. Having a central region 45 that is
non-perforated increases the stiffness of the disc 40. As a result,
a thinner disc may be employed. This then has the benefit that the
disc 40 may be manufactured in a more timely and cost-effective
manner Moreover, for certain methods of manufacture (e.g. chemical
etching), the thickness of the disc 40 may define the minimum
possible dimensions for the holes 47 and land. A thinner disc
therefore has the benefit that such methods may be used to
manufacture a disc having relatively small hole and/or land
dimensions. Furthermore, the cost and/or weight of the disc 40,
along with the mechanical power required to drive the disc 40, may
be reduced. Consequently, a less powerful, and potentially smaller
and cheaper motor 41 may be used to drive the disc 40.
[0041] By having a central non-perforated region 45, the dirt-laden
fluid entering the chamber 36 is forced to turn from an axial
direction to a radial direction. The dirt-laden fluid then moves
outward over the surface of the disc 40. This then has at least two
benefits. First, as the dirt-laden fluid moves over the perforated
region 46, the fluid is required to turn through a relatively large
angle (around 90 degrees) in order to pass through the holes 47 in
the disc 40. As a result, less of the dirt carried by the fluid is
able to match the turn and pass through the holes 47. Second, as
the dirt-laden fluid moves outward over the surface of the disc 40,
the dirt-laden fluid helps to scrub the perforated region 46.
Consequently, any dirt that may have become trapped at a hole 47 is
swept clear by the fluid.
[0042] The tangential speed of the disc 40 decreases from the
perimeter to the centre of the disc 40. As a result, the tangential
forces imparted to the dirt-laden fluid by the disc 40 decrease
from the perimeter to the centre. If the central region 45 of the
disc 40 were perforated, more dirt is likely to pass through the
disc 40. By having a central non-perforated region 45, the holes 47
are provided at regions of the disc 40 where the tangential speeds
and thus the tangential forces imparted to the dirt are relatively
high.
[0043] As the dirt-laden fluid introduced into the chamber 36 turns
from axial to radial, relatively heavy dirt may continue to travel
in an axial direction and impact the disc 40. If the central region
45 of the disc 40 were perforated, relatively hard objects
impacting the disc 40 may puncture or otherwise damage the land
between the holes 47. By having a central region 45 that is
non-perforated, the risk of damaging the disc 40 is reduced.
[0044] The diameter of the non-perforated region 45 is greater than
the diameter of the inlet 37. As a result, hard objects carried by
the fluid are less likely to impact the perforated region 46 and
damage the disc 40. Additionally, the dirt-laden fluid is better
encouraged to turn from an axial direction to a radial direction on
entering the chamber 36. The separation distance between the inlet
37 and the disc 40 plays an important part in achieving both these
benefits. As the separation distance between the inlet 37 and the
disc 40 increases, the radial component of the velocity of the
dirt-laden fluid at the perforated region 46 of the disc 40 is
likely to decrease. As a result, more dirt is likely to be carried
through the holes 47 in the disc 40. Additionally, as the
separation distance increases, hard objects carried by the fluid
are more likely to impact the perforated region 46 and damage the
disc 40. A relatively small separation distance is therefore
desirable. However, if the separation distance is too small, dirt
larger than the separation distance will be unable to pass between
the inlet duct 21 and the disc 40 and will therefore become
trapped. The size of the dirt carried by the fluid will be limited
by, among other things, the diameter of the inlet duct 21. In
particular, the size of the dirt is unlikely to be greater than the
diameter of the inlet duct 21. Accordingly, by employing a
separation distance that is no greater than the diameter of the
inlet 37, the aforementioned benefits may be achieved whilst
providing sufficient space for dirt to pass between the inlet duct
21 and the disc 40.
[0045] Irrespective of the separation distance that is chosen, the
non-perforated region 45 of the disc 40 continues to provide
advantages. In particular, the non-perforated region 45 ensures
that the holes 47 in the disc 40 are provided at regions where
tangential forces imparted to the dirt by the disc 40 are
relatively high. Additionally, although the dirt-laden fluid
follows a more divergent path as the separation distance increases,
relatively heavy objects are still likely to continue along a
relatively straight path upon entering the chamber 36. A central
non-perforated region 45 therefore continues to protect the disc 40
from potential damage.
[0046] In spite of the advantages, the diameter of the
non-perforated region 45 need not be greater than the diameter of
the inlet 37. By decreasing the size of the non-perforated region
45, the size of the perforated region 46 and thus the total open
area of the disc 46 may be increased. As a result, the pressure
drop across the dirt separator 10 is likely to decrease.
Additionally, a decrease in the axial speed of the dirt-laden fluid
moving through the perforated region 46 may be observed. However,
as the size of the non-perforated region 45 decreases, there will
come a point at which the fluid entering the chamber 36 is no
longer forced to turn from axial to radial before encountering the
perforated region 46. There will therefore come a point at which
the decrease in axial speed due to the larger open area is offset
by the increase in axial speed due to the smaller turn angle.
[0047] Conceivably, the central region 45 of the disc 40 may be
perforated. Although many of the advantages described above would
then be forfeited, there may nevertheless be advantages in having a
disc 40 that is fully perforated. For example, it may be simpler
and/or cheaper to manufacture the disc 40. In particular, the disc
40 may be cut from a continuously perforated sheet. Even if the
central region 45 were perforated, the disc 40 would continue to
impart tangential forces to the dirt-laden fluid entering the
chamber 36, albeit smaller forces at the centre of the disc 40. The
disc 40 would therefore continue to separate dirt from the fluid,
albeit at a reduced separation efficiency. Additionally, if the
central region 45 of the disc 40 were perforated, dirt may block
the holes at the very centre of the disc 40 owing to the relatively
low tangential forces imparted by the disc 40. With the holes at
the very centre blocked, the disc 40 would then behave as if the
centre of the disc 40 were non-perforated. Alternatively, the
central region 45 may be perforated but have an open area that is
less than that of the surrounding perforated region 46. Moreover,
the open area of the central region 45 may increase as one moves
radially outward from the centre of the disc 40. This then has the
benefit that the open area of the central region 45 increases as
the tangential speed of the disc 40 increases.
[0048] The inlet duct 21 is attached to and may be formed
integrally with the bottom wall 32. The inlet duct 21 is therefore
supported within the chamber by the bottom wall 32. The inlet duct
21 may alternatively be supported by the side wall 31 of the
container 20, e.g. using one or more braces that extend radially
between the inlet duct 21 and the side wall 31. This arrangement
has the advantage that the bottom wall 32 is free to open and close
without movement of the inlet duct 21. As a result, a taller
container 20 having a larger dirt capacity may be employed.
However, a disadvantage with this arrangement is that the braces
used to support the inlet duct 21 are likely to inhibit dirt
falling from the chamber 36 when the bottom wall 32 is opened, thus
making emptying of the container 20 more difficult.
[0049] The inlet duct 21 extends linearly within the chamber 36.
This then has the advantage that the dirt-laden fluid moves through
the inlet duct 21 along a straight path. However, this arrangement
is not without its difficulties. The bottom wall 32 is arranged to
open and close and is attached to the side wall 31 by means of a
hinge 33 and catch 34. Accordingly, when a user applies a force to
the handheld unit 2 in order to manoeuvre the cleaner head 4 (e.g.
a push or pull force in order to manoeuvre the cleaner head 4
forwards and backwards, a twisting force in order to steer the
cleaner head 4 left or right, or a lifting force in order to lift
the cleaner head 4 off the floor), the force is transferred to the
cleaner head 4 via the hinge 33 and catch 34. The hinge 33 and
catch 34 must therefore be designed in order to withstand the
required forces. As an alternative arrangement, the bottom wall 32
may be fixed to the side wall 31, and the side wall 31 may be
removably attached to the top wall 30. The container 20 is then
emptied by removing the side and bottom walls 31,32 from the top
wall 30 and inverting. Although this arrangement has the advantage
that it is not necessary to design a hinge and catch capable of
withstanding the required forces, the dirt separator 10 is less
convenient to empty.
[0050] FIG. 8 illustrates an alternative dirt separator 102 in
which the inlet duct 21 extends linearly through the side wall 31
of the container 20. The bottom wall 32 is then attached to the
side wall 31 by means of a hinge 33 and is held closed by a catch
34. In the arrangement illustrated in FIG. 3, the chamber 36 of the
dirt separator 10 is essentially cylindrical in shape, with the
longitudinal axis of the chamber 36 coincident with the rotational
axis 48 of the disc. The disc 40 is then located towards the top of
the chamber 36, and the inlet duct 21 extends upwardly from the
bottom of the chamber 36. Reference to top and bottom should be
understood to mean that dirt separated from the fluid collects
preferentially at the bottom of the chamber 36, and fills
progressively in a direction towards the top of the chamber 36.
With the arrangement shown in FIG. 8, the shape of the chamber 36
may be thought of as the union of a cylindrical top portion and a
cubical bottom portion. Both the disc 40 and the inlet duct 21 are
then located towards the top of the chamber 36. Since the inlet
duct 21 extends through the side wall 31 of the container 20, this
arrangement has the advantage that the container 20 may be
conveniently emptied via the bottom wall 32 without the need for a
hinge and catch capable of withstanding the forces required to
manoeuvre the cleaner head 4. The arrangement has at least three
further advantages. First, the dirt capacity of the dirt separator
102 is significantly increased. Second, when the handheld unit 2 is
inverted for above-floor cleaning, dirt within the container 20 is
less likely to fall onto the disc 40. There is therefore no need
for the chamber 36 to include a protective gulley around the disc
40, and thus a larger disc 40 having a larger total open area may
be used. Third, the bottom wall 32 of the container 20 may be used
to support the handheld unit 2 when resting on a level surface.
This arrangement is not, however, without its disadvantages. For
example, the larger container 20 may obstruct access to narrow
spaces, such as between items of furniture or appliances.
Additionally, the bottom of the chamber 36 is spaced radially from
the top of the chamber 36. That is to say that the bottom of the
chamber 36 is spaced from the top of the chamber 36 in a direction
normal to the rotational axis 48 of the disc 40. As a result, dirt
and fluid thrown radially outward by the disc 40 may disturb the
dirt collected in the bottom of the chamber 36. Additionally, any
swirl within the chamber 36 will tend to move up and down the
chamber 36. Consequently, re-entrainment of dirt may increase,
resulting in a decrease in separation efficiency. By contrast, in
the arrangement illustrated in FIG. 3, the bottom of the chamber 36
is spaced axially from the top of the chamber 36. Dirt and fluid
thrown radially outward by the disc 40 is therefore less likely to
disturb the dirt collected in the bottom of the chamber 36.
Additionally, any swirl within the chamber 36 moves around the
chamber 36 rather than up and down the chamber 36.
[0051] In the arrangements shown in FIGS. 3 and 8, the dirt-laden
fluid entering the chamber 36 is directed at the centre of the disc
40. This then has the advantage that the dirt-laden fluid is
distributed evenly over the surface of the disc 40. By contrast, if
the inlet duct 21 were directed off-centre at the disc 40, the
fluid would be unevenly distributed. This uneven distribution of
fluid is likely to have one or more adverse effects. For example,
the axial speed of the fluid through the disc 40 is likely to
increase at those regions that are most heavily exposed to the
dirt-laden fluid. As a result, the separation efficiency of the
dirt separator 10 is likely to decrease. Additionally, dirt
separated by the disc 40 may collect unevenly within the container
20. As a result, the capacity of the dirt separator 10 may be
compromised. Re-entrainment of dirt 50 already collected within the
container 20 may also increase, leading to a further decrease in
the separation efficiency. A further disadvantage of directing the
dirt-laden fluid off-centre is that the disc 40 is subjected to
uneven structural load. The resulting imbalance may lead to a poor
seal with the top wall 30 of the container 20, and may reduce the
lifespan of any bearings used to support the disc assembly 22
within the vacuum cleaner 1. In spite of the aforementioned
disadvantages, effective separation of dirt may nevertheless be
achieved by directing the dirt-laden fluid off-centre. Moreover,
there may be instances for which it is desirable to direct the
dirt-laden fluid off-centre. For example, if the central region of
the disc 40 were perforated, the dirt-laden fluid may be directed
off-centre so as to avoid the region of the disc 40 where
tangential speeds are slowest. As a result, a net gain in
separation efficiency may be observed. By way of example, FIG. 9
illustrates an arrangement in which the dirt-laden fluid entering
the chamber 36 is directed off-centre at the disc 40. The inlet
duct 21 is formed integrally with the side wall 31 of the container
20, and the bottom wall 32 is attached to the side wall 31 by a
hinge 33 and catch (not shown). When the bottom wall 32 moves
between the closed and opened positions, the position of the inlet
duct 21 remains fixed. This then has the advantage that the
container 20 is convenient to empty without the need to design a
hinge and catch capable of withstanding the forces required to
manoeuvre the cleaner head 4.
[0052] In a more general sense, the dirt-laden fluid may be said to
enter the chamber 36 along a flow axis 49. The flow axis 49 then
intersects the disc 40 such that the dirt-laden fluid is directed
at the disc 40. This then has the benefit that the dirt-laden fluid
impacts the disc 40 shortly after entering the chamber 36. The disc
40 then imparts tangential forces to the dirt-laden fluid. The
fluid is drawn through the holes 47 in the disc 40 whilst the dirt,
owing to its greater inertia, moves radially outward and collects
in the chamber 36. In the arrangements shown in FIGS. 3 and 8, the
flow axis 49 intersects the centre of the disc 40, whilst in the
arrangement shown in FIG. 9, the flow axis 49 intersects the disc
40 off-centre. Although there are advantages in having a flow axis
49 that intersects the centre of the disc 40, effective separation
of dirt may nevertheless be achieved by having a flow axis 49 that
intersects the disc 40 off-centre.
[0053] The dirt separator 10 illustrated in FIG. 3 comprises a
gulley that surrounds the disc 40. The gulley then acts to collect
dirt 50 that falls down the chamber 36 when the handheld unit 2 is
inverted, as illustrated in FIG. 7. The dirt separator may comprise
additional or alternative means for protecting the disc 40 from
dirt upon inverting the handheld unit 2. By way of example, FIGS.
10 to 12 illustrate an alternative arrangement in which the dirt
separator 105 comprises a flange 60 that extends outwardly from the
inlet duct 21. The flange 60 is located at the very end of the
inlet duct 21 and extends in a plane normal to the rotational axis
48 of the disc 40. When the handheld unit 2 is inverted, the flange
60 acts to protect the disc 40 from dirt falling down the chamber
36. Additionally, the flange 60 helps to reduce dirt
re-entrainment. As illustrated in FIG. 5, part of the fluid thrown
radially outward by the disc 40 circulates around the top portion
of the chamber 36. As the chamber 36 fills with dirt, this
circulating fluid may re-entrain dirt, resulting in a drop in
separation efficiency. The provision of the flange 60 forces the
circulating fluid to follow a more convoluted path back to the disc
40. As a result, dirt that may have been re-entrained is more
likely to drop out of the fluid flow.
[0054] Although the flange 60 is located at the very end of the
inlet duct 21, the same advantages would be observed if the flange
60 were located further along the inlet duct 21. However, as the
flange 60 moves further along the inlet duct 21, the dirt capacity
of the chamber 36 will be reduced if the flange 60 is used to
delimit the portion of the chamber 36 that is used to collect dirt.
By locating the flange 60 at or adjacent the end of the inlet duct
21, the advantages described above may be achieved without
impacting adversely the dirt capacity of the chamber 36.
[0055] In the particular arrangement illustrated in FIGS. 10 to 12,
the diameter of the flange 60 is slightly smaller than that of the
disc 40. A larger diameter flange 60 would better protect the disc
40. However, as the diameter of the flange 60 increases, the gap
between the flange 60 and the side wall 31 of the container 20
decreases. If the gap were too small, dirt may become trapped above
the flange 60. Additionally, for this particular arrangement, the
inlet duct 21 is attached to and is moveable with the bottom wall
32. If the flange 60 were too big, the flange 60 may prevent the
bottom wall 32 from moving between the open and closed positions.
Indeed, the flange 60 of this particular arrangement contacts the
side wall 31 of the container 20 when the bottom wall 32 moves
between the open and closed positions. In order that the flange 60
does not prevent the bottom wall 32 from opening and closing, the
flange 60 is formed of two portions: a rigid portion 61 and a
flexible portion 62. The rigid portion 61 is formed integrally with
the inlet duct 21, and the flexible portion 62 is formed of a
rubber material that is moulded onto the rigid portion 61. The
shape of the flange 60 may be regarded as an annulus that surrounds
the inlet duct 21, and the rigid and flexible portions 61,62 may be
regarded as major and minor segments that are joined along a chord
of the annulus. As illustrated in FIG. 12, when the bottom wall 32
moves between the open and closed positions, the flexible portion
62 of the flange 60 contacts the side wall 31 and flexes so as to
allow the bottom wall 32, inlet duct 21 and flange 60 to move
relative to the side wall 31.
[0056] Although the flange 60 comprises a flexible portion 62, it
will be appreciated that if the diameter of the side wall 31 were
slightly larger or if the diameter of the flange 60 were slightly
smaller, it would not be necessary to provide a flexible portion
62. That being said, the provision of a flexible portion 62 does
have the benefit that it enables a relatively tall inlet duct 21
and a relatively wide flange 60 to be used without necessarily
having a relatively wide side wall 31. A tall inlet duct 21 has the
benefit that a relatively tall chamber 36 may be employed whilst
also ensuring that the separation distance between the inlet 37 and
the disc 40 is relatively small. Having a wide flange 60, on the
other hand, better protects the disc 40.
[0057] Rather than comprising a flexible portion 62, the flange 60
as a whole may be flexible. This may facilitate empting of the
container 20, as will now be explained. Although it may be
advisable to empty the dirt separator 10 once dirt within the
chamber 36 has reached the flange 60, it is quite possible that a
user will continue to use the vacuum cleaner 1. Dirt would then
collect in the region of the chamber 36 located above the flange
60. Dirt that collects between the flange 60 and the top wall 32 of
the container 20, or between the flange 60 and the disc 40, may
become compressed and apply a downward force on the flange 60. If
the flange 60 were rigid, the downward force would be transferred
to the bottom wall 32, which in turn would move downwards relative
to the side wall 31. As a result, the catch 34 would butt against
the side wall 31 with a greater force, thus making it more
difficult to release the catch 34. If, on the other hand, the
flange 60 were flexible, the downward force applied to the flange
60 would cause the flange 60 to flex downwards. As a result,
movement of the bottom wall 32 would be reduced and thus the catch
34 would be easier to release.
[0058] In each of the arrangements described above, the inlet duct
21 has a circular cross-section and thus the inlet 37 has a
circular shape. Conceivably, the inlet duct 21 and the inlet 37 may
have alternative shapes. Likewise, the shape of the disc 40 need
not be circular. However, since the disc 40 rotates, it is not
clear what advantages would be gained from having a non-circular
disc. The perforated and non-perforated regions 45,46 of the disc
40 may also have different shapes. In particular, the
non-perforated region 45 need not be circular or located at the
centre of the disc 40. For example, where the inlet duct 21 is
directed off-centre at the disc 40, the non-perforated region 45
may take the form of an annulus. In the above discussions,
reference is sometimes made to the diameter of a particular
element. Where that element has a non-circular shape, the diameter
corresponds to the maximal width of the element. For example, if
the inlet 37 were rectangular or square in shape, the diameter of
the inlet 37 would correspond to the diagonal of the inlet 37.
Alternatively, if the inlet were elliptical in shape, the diameter
of the inlet 37 would correspond to the width of the inlet 37 along
the major axis.
[0059] The disc 40 is formed of a metal, such as stainless steel,
which has at least two advantages over, say, a plastic. First, a
relatively thin disc 40 having a relatively high stiffness may be
achieved. Second, a relatively hard disc 40 may be achieved that is
less susceptible to damage from hard or sharp objects that are
carried by the fluid or fall onto the disc 40 when the handheld
unit 2 is inverted, as shown in FIG. 7. Nevertheless, in spite of
these advantages, the disc 40 could conceivably be formed of
alternative materials, such as plastic. Indeed, the use of a
plastic may have advantages over a metal. For example, by forming
the disc 40 of a low-friction plastic, such as polyoxymethylene,
the ring of low-friction material (e.g. PTFE) provided around the
top wall 30 of the container 20 may be omitted.
[0060] In the arrangements described above, the disc assembly 22
comprises a disc 40 directly attached to a shaft of an electric
motor 41. Conceivably, the disc 40 may be attached indirectly to
the electric motor, e.g. by means of a gearbox or drive dog.
Furthermore, the disc assembly 22 may comprise a carrier to which
the disc 40 is attached. By way of example, FIG. 13 illustrates a
disc assembly 23 having a carrier 70. The carrier 70 may be used to
increase the stiffness of the disc 40. As a result, a thinner disc
40 or a disc 40 having a larger diameter and/or a larger total open
area may be used. The carrier 70 may also be used to form the seal
between the disc assembly 23 and the container 20. In this regard,
whilst a contact seal between the disc 40 and the top wall 30 has
thus far been described, alternative types of seal may equally be
employed, e.g. labyrinth seal or fluid seal. The carrier 70 may
also be used to obstruct the central region of a wholly perforated
disc. In the example shown in FIG. 13, the carrier 70 comprises a
central hub 71, connected to a rim 72 by radial spokes 73. Fluid
then moves through the carrier 70 via the apertures 74 between
adjacent spokes 73.
[0061] Each of the disc assemblies 22,23 described above comprises
an electric motor 41 for driving the disc 40. Conceivably, the disc
assembly 22,23 may comprise alternative means for driving the disc
40. For example, the disc 40 may be driven by the vacuum motor 12.
This arrangement is particularly viable with the layout shown in
FIG. 1, in which the vacuum motor 12 rotates about an axis that is
coincident with the rotational axis 48 of the disc 40.
Alternatively, the disc assembly 22,23 may comprise a turbine
powered by the flow of fluid moving through the disc assembly
22,23. A turbine is generally cheaper than an electric motor, but
the speed of the turbine, and thus the speed of the disc 40,
depends on the flow rate of fluid moving through the turbine. As a
result, high separation efficiencies can be difficult to achieve at
low flow rates. Additionally, if dirt were to clog any of the holes
47 in the disc 40, the open area of the disc 40 would decrease,
thereby restricting the flow of fluid to the turbine. As a result,
the speed of the disc 40 would decrease and thus the likelihood of
clogging would increase. A runway effect then arises in which the
disc 40 becomes increasingly slower as it clogs, and the disc 40
becomes increasingly clogged as it slows. Furthermore, if the
suction opening in the cleaner head 4 were to become momentarily
obstructed, the speed of the disc 40 would decrease significantly.
Dirt may then build up significantly on the disc 40. When the
obstruction is subsequently removed, the dirt may restrict the open
area of the disc 40 to such an extent that the turbine is unable to
drive the disc 40 at sufficient speed to throw off the dirt. An
electric motor, whilst generally more expensive, has the advantage
that the speed of the disc 40 is relatively insensitive to flow
rates or fluid speeds. As a result, high separation efficiencies
may be achieved at low flow rates and low fluid speeds.
Additionally, the disc 40 is less likely to clog with dirt. A
further advantage of using an electric motor is that it requires
less electrical power. That is to say that, for a given flow rate
and disc speed, the electrical power drawn by the electric motor 41
is less than the additional electrical power drawn by the vacuum
motor 12 in order to drive the turbine.
[0062] The dirt separator 10 has thus far been described as forming
part of a handheld unit 2 that may be used as a standalone cleaner
or may be attached to a cleaner head 4 via an elongate tube 3 for
use as a stick cleaner 1. However, it will be appreciated that the
dirt separator may equally be used in alternative types of vacuum
cleaner, such as an upright, canister or robotic vacuum
cleaner.
[0063] Although the dirt separators described herein comprises a
disc assembly 22 for separating dirt, there may be aspects of the
dirt separator that can be used with other types of dirt separator
that employ alternative means for separating dirt. In particular,
the flange 60 of the arrangement illustrated in FIGS. 10 to 12 may
be used to hamper dirt re-entrainment in other types of dirt
separator. For example, existing dirt separators may comprise a
plate that partitions a chamber in two. An upper part of the
chamber may then be used to separate dirt (e.g. using cyclonic
flow), and a lower part of the chamber may be used to collect the
separated dirt. The partition plate then hampers dirt collected in
the lower part of the chamber being re-entrained by the fluid
moving around the upper part. However, there is often a difficultly
in emptying the dirt from such dirt separators. With the
arrangement illustrated in FIGS. 10 to 12, the flange 60 extends
outwardly from a duct 21 that is attached to the bottom wall 32.
The flange 60 effectively divides the chamber 36 into an upper part
that is used to separate the dirt, and a lower part that is used to
collect the separated dirt. The bottom wall 32 moves between open
and closed positions such that the dirt 50 collected in the lower
part of the chamber 36 may be conveniently removed. As well as
carrying fluid to the chamber (or conceivably carrying fluid from
the chamber if used an outlet duct), the duct 21 acts to support
the flange 60 within the chamber 36. Consequently, in contrast to
existing dirt separators having a partition plate, the dirt
separator does not require an additional support element to hold
the flange at the appropriate position within the chamber. The duct
21 is attached to and is moveable with the bottom wall 32. This
then helps encourage dirt emptying when the bottom wall 32 moves to
the open position. For example, the moving duct 21 may push or pull
dirt out of the chamber 36. During use, dirt that collects in the
upper part of the chamber 36 may become compressed and apply a
downward force on the flange 60. As explained above, if the flange
60 were wholly rigid, the force would be transferred to the bottom
wall 32, which may then move relative to the side wall 31 when in
the closed position. As a result, the catch 34 used to retain the
bottom wall 32 in the closed position may be difficult to release.
However, by making at least part of the flange 60 flexible, the
downward force applied to the flange 60 will cause that part of the
flange 60 to flex downwards. As a result, movement of the bottom
wall 32 is reduced, thus making it easier to release the bottom
wall 32 from the closed position. These aspects and advantages of
the dirt separator may be used with other types of dirt separator
irrespective of the means employed to separate dirt.
* * * * *