U.S. patent application number 13/679558 was filed with the patent office on 2013-11-28 for cleaner head.
This patent application is currently assigned to DYSON TECHNOLOGY LIMITED. The applicant listed for this patent is DYSON TECHNOLOGY LIMITED. Invention is credited to Spencer James Robert ARTHEY, Henry Licming LAMBOURN, Alexander Stuart LAMOURY, Victoria Isabelle PALMER.
Application Number | 20130312216 13/679558 |
Document ID | / |
Family ID | 45475386 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130312216 |
Kind Code |
A1 |
PALMER; Victoria Isabelle ;
et al. |
November 28, 2013 |
CLEANER HEAD
Abstract
A cleaner head for a vacuum cleaning appliance includes a
suction cavity having a downwardly-directed opening through which
debris enters the suction cavity. The opening is bounded in part by
a front edge and a rear edge which is substantially co-planar with
the front edge. A thread lifting strip is mounted on a support
located within and moveable relative to the suction cavity. A
spring urges the support in a direction extending towards the
opening.
Inventors: |
PALMER; Victoria Isabelle;
(Malmesbury, GB) ; LAMBOURN; Henry Licming;
(Malmesbury, GB) ; ARTHEY; Spencer James Robert;
(Malmesbury, GB) ; LAMOURY; Alexander Stuart;
(Malmesbury, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DYSON TECHNOLOGY LIMITED |
Wiltshire |
|
GB |
|
|
Assignee: |
DYSON TECHNOLOGY LIMITED
Wiltshire
GB
|
Family ID: |
45475386 |
Appl. No.: |
13/679558 |
Filed: |
November 16, 2012 |
Current U.S.
Class: |
15/393 |
Current CPC
Class: |
A47L 9/0666 20130101;
A47L 9/066 20130101; A47L 9/0653 20130101; A47L 9/0613
20130101 |
Class at
Publication: |
15/393 |
International
Class: |
A47L 9/06 20060101
A47L009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2011 |
GB |
1119946.0 |
Oct 3, 2012 |
GB |
1217703.6 |
Claims
1. A cleaner head for a vacuum cleaning appliance, the cleaner head
comprising: a suction cavity having a downwardly-directed opening
through which debris enters the cleaner head; and a thread lifting
strip located within the suction cavity and which is moveable
relative to the opening.
2. The cleaner head of claim 1, wherein the thread lifting strip is
moveable relative to a plane containing the opening.
3. The cleaner head of claim 1, wherein the thread lifting strip is
moveable towards and away from the opening.
4. The cleaner head of claim 1, wherein the thread lifting strip is
connected to a surface of a wall of the cleaner head.
5. The cleaner head of claim 4, wherein the surface is located
within the suction cavity.
6. The cleaner head of claim 1, wherein the suction cavity
surrounds the thread lifting strip.
7. The cleaner head of claim 1, wherein the thread lifting strip is
biased towards a plane containing the opening.
8. The cleaner head of claim 1, wherein the thread lifting strip is
moveable relative to the opening.
9. The cleaner head of claim 8, comprising a support on which the
thread lifting strip is disposed, and wherein the support is
moveable relative to the opening.
10. The cleaner head of claim 9, wherein the support is biased
towards a plane containing the opening.
11. The cleaner head of claim 9, comprising at least one resilient
member for urging the support towards a plane containing the
opening.
12. The cleaner head of claim 11, wherein the at least one
resilient member comprises at least one torsion spring.
13. The cleaner head of claim 9, wherein the thread lifting strip
is mounted on the support.
14. The cleaner head of claim 9, wherein the support is connected
to a cavity wall defining, at least in part, the suction
cavity.
15. The cleaner head of claim 14, wherein the support is pivotably
connected to the cavity wall.
16. The cleaner head of claim 15, wherein the support is pivotable
about an axis extending substantially parallel to a plane
containing the opening.
17. The cleaner head of claim 14, wherein the cavity wall defines
one of a front edge and a rear edge of the opening.
18. The cleaner head of claim 14, wherein the support comprises at
least one arm which extends outwardly therefrom and which is
connected to the cavity wall for movement relative thereto.
19. The cleaner head of claim 9, wherein the support is moveable
between a raised position and a lowered position, and the cleaner
head comprises a stop member for inhibiting movement of the support
beyond the lowered position.
20. The cleaner head of claim 19, wherein the support comprises
said stop member.
21. The cleaner head of claim 19, wherein the stop member is
arranged to abut a surface defining, at least in part, said suction
cavity.
22. The cleaner head of claim 19, wherein the thread lifting strip
is located within a recessed portion of the support.
23. The cleaner head of claim 22, wherein the recessed portion of
the support comprises a front support edge and a rear support edge,
and wherein the edges do not extend downwardly beyond a plane
containing the opening when the support is in its lowered
position.
24. The cleaner head of claim 23, wherein one of the support edges
protrudes further from the support than the other support edge.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of United Kingdom
Application No. 1119946.0, filed Nov. 18, 2011, and United Kingdom
Application No. 1217703.6, filed Oct. 3, 2012, the entire contents
of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a cleaner head for a
cleaning appliance. In a preferred embodiment, the cleaner head is
suitable for use with a vacuum cleaning appliance.
BACKGROUND OF THE INVENTION
[0003] A vacuum cleaner typically comprises a main body containing
dirt and dust separating apparatus, a cleaner head connected to the
main body and having a suction opening, and a motor-driven fan unit
for drawing dirt-bearing air through the suction opening and the
cleaner head, and into the main body. The suction opening is
directed downwardly to face the floor surface to be cleaned. The
dirt-bearing air is conveyed to the separating apparatus so that
dirt and dust can be separated from the air before the air is
expelled to the atmosphere. The separating apparatus can take the
form of a filter, a filter bag or a cyclonic arrangement.
[0004] Vacuum cleaners generally include cylinder, or canister,
cleaners, upright cleaners and hand-held cleaners. A cylinder
vacuum cleaner includes a main body supported by a set of wheels
which is dragged along a floor surface by a hose and wand assembly
extending between the main body and the cleaner head. The cleaner
head is generally releasably attached to the end of the wand which
is remote from the main body. In use, a user pushes and pulls the
wand to move the cleaner head forwards and backwards over the floor
surface. An upright vacuum cleaner typically comprises a main body,
a rolling assembly mounted on the main body for manoeuvring the
vacuum cleaner over a floor surface to be cleaned, and a cleaner
head mounted on the main body. In use, a user reclines the main
body of the upright vacuum cleaner towards the floor surface, and
then sequentially pushes and pulls a handle which is attached to
the main body to manoeuvre the vacuum cleaner over the floor
surface.
[0005] A cleaner head may be provided with one or more of a number
of features for improving the removal of dirt, dust or other debris
from a surface to be cleaned. For example, the cleaner head may be
provided with a brush for sweeping debris from a hard floor
surface. As another example, the cleaner head may be provided with
a rotatable brush bar comprising an elongate cylindrical core
bearing bristles which extend radially outward from the core. The
rotation of the brush bar causes the bristles to be swept between
the fibres of the carpet to be cleaned, agitating both the fibres
of the carpet and any debris, such as dust particles, fibres and
hairs, located on the surface of the carpet and/or between the
fibres of the carpet.
[0006] It is also known to provide cleaner heads which have a
suction opening which is bounded on each side by a respective
working edge for agitating the fibres of a carpeted floor surface
as the cleaner head is manoeuvred over such a surface. For example,
WO 2002/026097 describes a cleaner head having a bottom surface
which defines a suction opening through which a dirt-bearing air
flow is drawn into a suction cavity. The bottom surface has an
inclined leading section extending forwardly from the suction
opening, and which defines a sharp front working edge at its
intersection with a front wall of the suction cavity. The bottom
surface also has an inclined trailing section extending rearwardly
from the suction opening, and which defines a sharp rear working
edge at its intersection with a rear wall of the suction cavity.
With each forward and reverse stroke of the cleaner head over a
carpeted floor surface, air drawn from the atmosphere passes
beneath one of these working edges of the head to enter the suction
cavity.
[0007] The action of pushing the cleaner head forwardly over the
floor surface causes the leading section of the bottom surface to
be pushed into the fibres of the carpet, concentrating the downward
force applied to the carpet on the front working edge. As the
leading section moves over the fibres, the upper ends of the fibres
are deflected temporarily in a forwards direction to subsequently
spring back into the suction cavity. This rapid movement of the
fibres causes dirt and dust to be dislodged from between the fibres
and into the suction cavity, where it becomes entrained within the
air flow passing beneath the front working edge and into the
suction channel.
[0008] A similar action takes place as the cleaner head is pulled
rearwardly over the floor surface; pulling the cleaner head
rearwardly over the floor surface causes the trailing section of
the bottom surface to be pulled into the carpet fibres,
concentrating the downward force on the rear working edge. As the
trailing section moves over the fibres, the upper ends of the
fibres are deflected temporarily in a rearward direction to
subsequently spring back into the suction cavity. Dislodged dirt
and dust enters the suction cavity to become entrained within the
air flow passing beneath the rear working edge and into the suction
channel.
[0009] The presence of these working edges can increase
significantly the efficiency with which dirt and dust is removed
from between the fibres of a carpet. To improve the efficiency with
which threads, hair and the like, generally referred to as "lint",
are removed from the surface of a carpet, a thread lifting strip,
also referred to as a thread collecting strip or a lint picker, is
located on each of the leading section and the trailing section of
the bottom surface, adjacent the working edge defined by that
section. Each thread lifting strip is generally in the form of a
pad adhered or otherwise attached to the cleaner head, and having a
fibrous lower surface. The fibres of the rear thread lifting strip
are inclined in a common direction to collect lint from the carpet
as the cleaner head is moved in a forward direction over the
carpet, and to release the collected lint when the cleaner head is
pulled rearwardly over the carpet. The fibres of the front thread
lifting strip are aligned in the opposite direction to the fibres
of the rear thread lifting strip so as to collected lint as the
cleaner head is pulled rearwardly over the carpet, and to release
the collected lint when the cleaner head is pushed forwardly over
the carpet.
[0010] The collected lint tends not to be released immediately from
the thread lifting strip; instead the collected lint tends to
agglomerate to form a mass which is eventually released from the
thread lifting strip when its surface area is sufficiently large as
to cause the collected lint to be torn from the thread lifting
strip by the air flow passing towards the suction cavity. Depending
on the size of the agglomerated lint, it may not be able to pass
immediately into the suction cavity between the carpet and the
bottom surface of the cleaner head and so may remain on the floor
surface. In this case the user may have to re-position the cleaner
head over the released lint so that it can be drawn into the
suction cavity.
[0011] When a thread lifting strip is located on a surface that is
inclined towards the suction opening to define a working edge, that
thread lifting strip can tend not to be intimate contact with the
carpet across its entire width. This can have the effect that the
portion of the thread lifting strip located remote from its
adjacent working edge can be less efficient at collecting lint than
the portion of the thread lifting strip which is closest to its
adjacent working edge. Also, as the cleaner head is moved forwards
and backwards over the floor surface by the user, the cleaner head
can tend to rock forwards and backwards, alternately raising and
lowering the thread lifting strips relative to the floor surface.
As the raising of a thread lifting strip tends to occur during the
stroke in which that thread lifting strip is arranged to collect
lint, the reduced intimacy of the contact between the raised thread
lifting strip and the carpet can further reduce the efficiency of
the thread lifting strip.
SUMMARY OF THE INVENTION
[0012] In a first aspect, the present invention provides a cleaner
head for a vacuum cleaning appliance, the cleaner head comprising a
suction cavity having a downwardly-directed opening through which
debris enters the cleaner head, and a thread lifting strip which is
moveable relative to the opening.
[0013] As the cleaner head is manoeuvred over a carpet a force is
applied in a downwards direction to the carpet by the portions of
the cleaner head that are in contact with the carpet. These
portions of the cleaner head may be support members for supporting
the cleaner head as it manoeuvred over the floor. These supports
may be in the form of wheels or casters. Alternatively, or
additionally, these portions may be in the form of at least one
edge of the opening through which dirt and debris enters the
cleaner head.
[0014] The contact between the thread lifting strip and the carpet
increases the surface area of the cleaner head that is in contact
with the carpet at any given moment, with the result that the
downwards force applied to the fibres of the carpet by the other
features of the cleaner head decreases. If the thread lifting strip
were to be located in a fixed position relative to the opening, the
proportion of the downwards force applied to the carpet by the
thread lifting strip may become sufficiently high as to impair the
agitation of the fibres of the carpet by, for example, the edges of
the opening, through a reduction in the proportion of the force
applied to the fibres by these edges, and thereby reduce the
performance of the cleaner head for removing dirt and dust trapped
between the carpet fibres. In view of this, the thread lifting
strip is arranged so as to be moveable relative to the opening.
This can reduce the proportion of the downwardly directed force
which is applied to the carpet by the thread lifting strip.
[0015] The thread lifting strip may be spaced from the suction
cavity. For example, the thread lifting strip may be located in
front of or behind the suction cavity. The suction cavity may be
formed from a front section and a rear section fluidly connected to
the front section, and the thread lifting strip may be located
between these sections. The suction cavity may therefore extend
about the thread lifting strip, but without the thread lifting
strip being located within the suction cavity. In these cases, the
thread lifting strip is moveable relative to a plane containing the
opening.
[0016] In a preferred embodiment however, the thread lifting strip
is located within the suction cavity. As the cleaner head is
manoeuvred over a carpeted floor surface during use, the reduced
air pressure within the suction cavity causes a portion of the
carpet to rise into the suction cavity to produce a carpet "hill".
The provision of a thread lifting strip within the suction cavity
can enable the thread lifting strip to be placed in intimate
contact with the carpet hill during both forwards and backwards
strokes of the cleaner head over the carpet, increasing the
efficiency of both the collection of lint by the thread lifting
strip and the subsequent release of lint from the thread lifting
strip. As the collected lint is released from the thread lifting
strip, it is drawn immediately into the suction cavity, that is,
without having to pass beneath an edge of the opening or other
feature of the lower surface of the cleaner head. In this case, the
thread lifting strip is moveable towards and away from the
opening.
[0017] The cleaner head may comprise a single suction cavity. The
suction cavity may comprise a single section arranged to receive
air from the opening and to expel air from the suction cavity.
Alternatively, the suction cavity may comprise a front section and
a rear section each having a respective opening, with the rear
section being arranged to receive air from the front section, and
to expel air from the suction cavity. In this case, the thread
lifting strip may be located in either the front section or the
rear section of the suction cavity.
[0018] The thread lifting strip may be connected to any surface of
the cleaner head. Where the thread lifting strip is located outside
of the suction cavity, the thread lifting strip may be connected to
any external surface of the cleaner head, such as the external
surface of a body defining the suction cavity or the external
surface of a hose for conveying air from an outlet of the suction
cavity to an outlet of the cleaner head. Alternatively, when it is
located beneath the cleaner head, but external to the suction
cavity, the thread lifting strip may be connected to an internal
surface of the cleaner head.
[0019] Preferably, the thread lifting strip is connected to a
surface located within the suction cavity. This surface may be part
of a wall defining, at least in part, the suction cavity. This
surface may be a surface of a side wall of the suction cavity, or
the surface of an upper wall of the suction cavity. The thread
lifting strip may extend between two side walls of the suction
cavity, whereby one end of the thread lifting strip is connected to
one side wall and the other end of the thread lifting strip is
connected to the other side wall. Alternatively, the thread lifting
strip may be connected to a surface extending across the suction
cavity. This may be in the form of an internal wall or other
feature located within the suction cavity.
[0020] At least part of the thread lifting strip is preferably
biased towards a plane containing the opening. This can enable an
intimate contact to be maintained between the thread lifting strip
and the carpet with, for example, any variation in the distance
between the upper surface of the carpet and the plane containing
the opening as the cleaner head is manoeuvred over the carpet.
[0021] The thread lifting strip may be biased towards the plane of
the opening during only part of the movement of the cleaner head
over a floor surface. In this case, the thread lifting strip may be
moved away from the plane of the opening during the other one of a
forward stroke or a reverse stroke of the cleaner head over the
floor surface. For example, a rotatable wheel may be provided on
the cleaner head for engaging the floor surface. The wheel may be
connected to a mechanism for moving the thread lifting strip
towards or away from the plane of the opening depending on the
rotational direction of the wheel as the cleaner head is manoeuvred
over the floor surface.
[0022] Alternatively, the thread lifting strip may be biased
towards the plane of the opening during both forward and reverse
strokes of the cleaner head over the floor surface. The thread
lifting strip may be biased towards the plane of the opening in a
number of different ways. As discussed above, a thread lifting
strip generally comprises an array of unidirectional fibres
disposed on a backing member. This backing member may be formed
from resilient material, such as a metallic, plastics or rubber
material. In this case, the attachment of the ends of the thread
lifting strip to a surface of the cleaner head, or between two
surfaces of the cleaner head, so that at least some of the fibres
face the plane of the opening can result in at least those fibres
of the thread lifting strip being urged towards the plane of the
opening by the resilient backing member. Alternatively, the cleaner
head may comprise a resilient member, such as a spring or other
elastic member, for engaging the backing member to urge the fibres
of the thread lifting strip towards the plane of the opening. This
resilient member may be located between the thread lifting strip
and a downwardly-facing surface of the cleaner head, such as the
bottom surface of the cleaner head or the upper surface of the
suction cavity. As a further alternative, the thread lifting strip
may comprise a plurality of relatively moveable sections. These
sections may be hingedly connected, end to end, so that at least
the centrally disposed sections are urged towards the plane of the
opening.
[0023] The cleaner head may comprise means for moving the thread
lifting strip relative to the opening. The moving means may
comprise a support on which the thread lifting strip is disposed,
and which is moveable relative to the opening. The thread lifting
strip may be mounted on the support, for example by using an
adhesive to attach a backing member of the thread lifting strip to
the support. Alternatively, the fibres of the thread lifting strip
may be disposed directly on the support, for example using an
adhesive. In this case, the adhesive may be considered to form the
backing member of the thread lifting strip.
[0024] The support may be biased towards the plane of the opening.
The support may be biased under its own weight towards the plane of
the opening. Alternatively, the support may be formed from
resilient material, such as a metallic, plastics or rubber
material.
[0025] In a preferred embodiment, resilient means are provided for
biasing the support towards the plane of the opening. The resilient
means may comprise one or more resilient members, such as springs
or other elastic members, for engaging the support to urge the
thread lifting strip towards the plane of the opening. These
resilient members may be located between the support and a
downwardly-facing surface of the cleaner head, such as the bottom
surface of the cleaner head or the upper surface of the suction
cavity. The resilient members may be located outside of the suction
cavity. For example, the support may comprise a rod, shaft or other
elongate member which extends through an aperture formed in an
upper wall of the suction cavity, and a resilient member, such as a
tension spring, may be disposed between the end of the elongate
member and the upper wall of the suction cavity to urge the support
towards the opening.
[0026] Alternatively, the resilient means may be located inside the
suction cavity, and disposed between the support and a surface of
the suction cavity. The resilient means may be provided by one or
more elastic members. Each of these elastic members may be in the
form of a spring, such as a torsion spring or a compression spring,
for urging the support in a direction extending towards the
opening, or a flexible connector for connecting the support to the
suction cavity. This flexible connector may be integral with at
least one of the support and the suction cavity.
[0027] The support is preferably connected to a cavity wall
defining, at least in part, the suction cavity. This cavity wall
may be an upper wall or a side wall of the suction cavity. The
support may be connected to the cavity wall for sliding movement
relative to, or along the cavity wall. Alternatively, the support
may be connected to the cavity wall for movement towards or away
from the cavity wall. In one embodiment, the support is pivotably
connected to the cavity wall. This cavity wall may be a wall of the
suction cavity which defines one of the front edge and the rear
edge of the opening, or it may be a side wall of the suction
cavity.
[0028] The support is preferably pivotable about an axis extending
substantially parallel to a plane within which the opening is
located. The support may comprise at least one arm which extends
outwardly therefrom and which is connected to the cavity wall for
movement relative thereto. At least one of the cavity wall and the
support may be shaped to define a channel between the cavity wall
and the support so that the suction cavity surrounds the support.
For example, the length of the arm(s) connecting the support to the
cavity wall may be selected to space the support from the cavity
wall.
[0029] One end of the resilient means may be connected to, or
engage, the cavity wall and the other end of the resilient means
may be connected to, or engage, the support to urge the support
towards the opening.
[0030] The cleaner head preferably comprises means for inhibiting
thread wrapping around the thread lifting strip. This thread
wrapping inhibiting means is preferably located between the support
and the cavity wall so that the thread wrapping inhibiting means is
at least partially located within the channel disposed between the
support and the cavity wall. The thread wrapping inhibiting means
thus provides a barrier between the support and the cavity wall
which prevents the ends of collected threads or hairs from wrapping
around the support before they can be released from the thread
lifting strip with movement of the cleaner head over the carpet.
The thread wrapping inhibiting means is preferably connected to at
least one of the support and the cavity wall. As a first example,
the thread wrapping inhibiting means may comprise a grille or mesh
which is connected to one of the support and the cavity wall. As a
second example, the thread wrapping inhibiting means may comprise a
set of ribs connected to one of the support and the cavity wall and
which extend towards the other of the support and the cavity wall.
As a third example, the thread wrapping inhibiting means may
comprise a first set of ribs connected to the support and a second
set of ribs connected to the cavity wall. Each rib of the first set
of ribs is preferably located adjacent to a rib of the second set
of ribs.
[0031] The thread lifting strip is preferably aligned so as to be
substantially parallel to the front and rear edges of the opening.
The thread lifting strip may extend partially or substantially
fully across the suction cavity.
[0032] The support is preferably moveable relative to the opening
between a raised position and a lowered position. A stop member is
preferably provided for inhibiting movement of the stop member
beyond the lowered position. The stop member may be located on the
support. The stop member may be arranged to abut a surface
defining, at least in part the suction cavity, or another surface
located within or outside the cavity.
[0033] The thread lifting strip is preferably located within a
recessed portion of the support. The thread lifting strip is
preferably connected to this recessed portion of the support using
an adhesive. The recessed portion of the support preferably
comprises a front edge and a rear edge, each extending towards the
opening, and one of these edges of the support preferably extends
downwardly beyond the other of these edges. The thread lifting
strip preferably comprises an array of fibres which are inclined
towards this one of the edges. This can enable lint which has
accumulated on the surface of the thread lifting strip to become
trapped or "pinched" between this edge and the carpet as the
cleaner head is manoeuvred over the carpet, and this can assist in
the removal of the accumulated lint from the thread lifting
strip.
[0034] The support is preferably biased towards a position in which
said one of the edges of the support is substantially co-planar
with the front and rear edges of the opening. This prevents this
surface from protruding downwardly beyond the opening and so
prevents the edge from being urged against a hard floor surface on
which the cleaner head is located. In this position, the lower
surface of the thread lifting strip is preferably substantially
parallel to the opening. The stop member is preferably arranged to
contact a wall of the suction cavity to inhibit movement of the
support beyond this position. This wall may be the cavity wall to
which the support is connected. This edge of the support may be
substantially parallel to the front edge and the rear edge of the
opening. The edge is preferably relatively sharp, and so the edge
is preferably defined by an edge of a surface, in the form of
either a leading or a trailing section of the lower surface of the
support, which is inclined relative to the lower surface of the
thread lifting strip.
[0035] A plurality of thread lifting strips may be located on the
support. The thread lifting strips may be arranged end to end or in
a staggered arrangement along or on the support, with the fibres of
the strips being aligned in a common direction. Alternatively, the
thread lifting strips may be arranged in a side by side
arrangement, with the fibres of the thread lifting strips being
arranged in opposing directions. In this case, one thread lifting
strip may collect lint during a forward stroke of the cleaner head
over a carpet, and the other thread lifting strip may collect lint
during a reverse stroke of the cleaner head over the carpet. An air
channel may be provided between the thread lifting strips. As a
further alternative, the cleaner head may be provided with two
supports each comprising a respective thread lifting strip.
[0036] The cleaner head preferably comprises a bottom surface
defining said opening. The bottom surface preferably has a leading
section extending forwardly from the front edge of the opening and
a trailing section extending rearwardly from the rear edge of the
opening. Each of these sections is preferably inclined relative to
the plane containing the opening to define relatively sharp front
and rear edges of the opening. At least one of the leading section
of the bottom surface and the trailing section of the bottom
surface may comprise a second thread lifting strip. This second
thread lifting strip preferably extends substantially the entire
width of the cleaner head, and is preferably substantially parallel
to the front and rear edges of the opening.
[0037] In a second aspect, the present invention provides a cleaner
head for a vacuum cleaning appliance, the cleaner head comprising a
suction cavity having a downwardly-directed opening through which
debris enters the suction cavity, the opening being bounded in part
by a front edge and a rear edge, a support located within and
moveable relative to the suction cavity, a thread lifting strip
mounted on the support, and resilient means for urging the support
in a direction extending towards the opening.
[0038] Features described above in connection with the first aspect
of the invention are equally applicable to the second aspect of the
invention, and vice versa.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Preferred features of the invention will now be described,
by way of example only, with reference to the accompanying
drawings, in which:
[0040] FIG. 1 is a front perspective view, from above, of a first
example of a cleaner head;
[0041] FIG. 2 is a front perspective view, from below, of the
cleaner head of FIG. 1;
[0042] FIG. 3 is a bottom view of the cleaner head of FIG. 1;
[0043] FIG. 4 is a front portion of a side cross-section taken
along line A-A in FIG. 3;
[0044] FIG. 5 is a front portion of a side cross-sectional view
taken along line B-B in FIG. 3;
[0045] FIG. 6 is a front perspective view, from above, of a second
example of a cleaner head;
[0046] FIG. 7 is a front perspective view, from below, of the
cleaner head of FIG. 6;
[0047] FIG. 8 is a rear perspective view, from below, of the
cleaner head of FIG. 6;
[0048] FIG. 9 is a bottom view of the cleaner head of FIG. 6;
[0049] FIG. 10 is a front portion of a side cross-sectional view
taken along line A-A in FIG. 9;
[0050] FIG. 11 is a front portion of a side cross-sectional view
taken along line B-B in FIG. 9; and
[0051] FIG. 12 is a front portion of a side cross-sectional view
taken along line C-C in FIG. 9.
DETAILED DESCRIPTION OF THE INVENTION
[0052] FIGS. 1 to 3 are external views of a first example of a
cleaner head 10 for a vacuum cleaning appliance. The cleaner head
10 comprises a main body 12 and a pair of wheels 14 arranged to
allow the cleaner head 10 to be manoeuvred over a floor surface.
Each wheel 14 is rotatably connected to a respective arm 16
extending rearwardly from the main body 12. The cleaner head 10
further comprises a connector 18 having an open end which is
connectable to a wand or hose of a vacuum cleaner.
[0053] The main body 12 comprises a lower body section 20 and an
upper body section 22 extending over and around the lower body
section 20. The lower body section 20 defines a suction cavity of
the cleaner head 10. In use, the suction cavity faces the floor
surface to be cleaned and admits dirt-bearing air from the floor
surface into the cleaner head 10.
[0054] In this example though, the suction cavity comprises a front
suction cavity section 24 and a rear suction cavity section 26.
Each suction cavity section 24, 26 extends substantially fully
across the lower body section 20. The front suction cavity section
24 is located towards the front of the main body 12, and the rear
suction cavity section 26 is located towards the rear of the main
body 12, behind the front suction cavity section 24. The front
suction cavity section 24 has a downwardly-directed suction opening
28 through which a first dirt-bearing air flow enters the front
suction cavity section 24, and the rear suction cavity section 26
has a downwardly-directed suction opening 30 through which a second
dirt-bearing air flow enters the rear suction cavity section
26.
[0055] Each of the suction openings 28, 30 is defined by the bottom
surface 32 of the lower body section 20. The suction opening 28 is
delimited by side walls 34, 36, a relatively long front wall 38 and
a relatively long rear wall 40 which each upstand from the bottom
surface 32 of the lower body section 20. A front working edge 42 of
the suction opening 28 is defined at the intersection between the
bottom surface 32 and the front wall 38, and a rear working edge 44
of the suction opening 28 is defined at the intersection between
the bottom surface 32 and the rear wall 40.
[0056] The suction opening 30 is delimited by side walls 46, 48, a
relatively long front wall 50 and a relatively long rear wall 52
which each also upstand from the bottom surface 32 of the lower
body section 20. A channel 54 extending through the main body 12
separates the rear wall 40 of the front suction cavity section 24
from the front wall 50 of the rear suction cavity section 26. The
channel 54 is split into two portions, with the upper end of each
portion of the channel 54 being open to the atmosphere. A front
working edge 56 of the suction opening 30 is defined at the
intersection between the bottom surface 32 and the front wall 50,
and a rear working edge 58 of the suction opening 30 is defined at
the intersection between the bottom surface 32 and the rear wall
52.
[0057] The working edges 42, 44, 56, 58 are substantially
co-planar, located within a plane P.sub.1, identified in FIG. 4,
containing the suction openings 28, 30. Each of the working edges
42, 44, 56, 58 is preferably relative sharp, preferably having a
radius of curvature less than 0.5 mm. To prevent the working edges
42, 44, 56, 58 from scratching or otherwise marking a hard floor
surface as the cleaner head 10 is manoeuvred over such a surface,
the cleaner head 10 comprises surface engaging support members
which serve to space the working edges 42, 44, 56, 58 from a hard
floor surface. In this embodiment, the cleaner head 10 comprises a
pair of wheels 60 rotatably mounted within a pair of recesses
formed in the lower body section 20. As shown in FIG. 5, the wheels
60 protrude downwardly beyond the working edges 42, 44, 56, 58 so
that the lowermost extremities of the wheels 60 are disposed
beneath the working edges 42, 44, 56, 58.
[0058] During use, a pressure difference is generated between the
air passing through the cleaner head 10 and the external
environment. This pressure difference generates a force which acts
downwardly on the cleaner head 10 towards the floor surface. When
the cleaner head 10 is located on a carpeted floor surface, the
wheels 60 are pushed into the fibres of the carpet under the weight
of the cleaner head 10 and the force acting downwardly on the
cleaner head 10. The thickness of the wheels 60 is selected so that
the wheels 60 will readily sink into the carpet to bring at least
the working edges 42, 44, 56, 58 of the main body 12 into contact
with the fibres of the carpet. The thickness of the wheels 60 is
preferably less than 5 mm.
[0059] The front suction cavity section 24 is connected to the rear
suction cavity section 26 by intermediate channels 62 which convey
the first dirt-bearing air flow into the rear suction cavity
section 26. Each channel 62 is located towards a respective side of
the main body 12, and passes beneath part of the bottom surface 32
of the lower body section 20. The rear suction cavity section 26
comprises an air outlet 64 through which both the first and second
dirt-bearing air flows are emitted from the suction cavity. The air
flows pass through a flexible hose 66 supported by the wheels 14
towards the connector 18. One end portion of the hose 66 has a wide
mouth that fits over and seals against the air outlet 64. The other
end of the internal hose 66 has a circular cross-section and is
arranged to fit over and seal against a neck 68 that, in turns,
fits inside the connector 18. The neck 68 is connected to,
preferably integral with, a second pair of arms 70 which extend
towards the main body 12 of the cleaner head 10. Each arm 70 is
pivotably connected towards one end thereof to a first end of a
respective one of a third pair of arms 72. This provides a first
articulated joint of the cleaner head 10. The second end of each of
the arms 72 is pivotably connected to a respective arm 16 of the
main body 12 of the cleaner head 10. This provides a second
articulated joint of the cleaner head 10. The first and second
joints pivot about axes that are parallel to the plane P.sub.1. The
connector 18 is arranged to rotate with respect to the neck 68
about an axis that is orthogonal to the axes of the first and
second joints. The rotatable connection of the neck 68 with the
connector 18 forms a third joint which allows the cleaner head 10
to move laterally. In use, the three joints allow the cleaner head
10 to be manipulated and steered while maintaining contact of the
working edges 42, 44, 56, 58 with the carpet.
[0060] A bleed valve 74 is provided in a cavity 76 located between
the lower body section 20 and the upper body section 22 of the main
body 12. The cavity 76 has an upper aperture 78 open to the
atmosphere and which is defined by a valve seat. The cavity 76 also
has a plurality of lower apertures 80 in communication with the air
outlet 64. The bleed valve 74 is biased by a spring 82 into
engagement with the valve seat so that, during normal use of the
cleaner head 10, there is no air flow through the cavity 76. In the
event that the suction cavity becomes blocked, for example, by
fabric being drawn into one of the suction cavities 24, 26, the
pressure at the air outlet 64 will drop. When the pressure inside
the suction cavity falls below a predetermined value, atmospheric
pressure acting on the bleed valve 74 urges it downwardly against
the force of the spring 82, thereby providing a flow path for
atmospheric air to enter the cleaner head 10. When the blockage is
removed, the air pressure at the air outlet 64 will rise, reducing
the force acting on the bleed valve 74 by the atmospheric air to
enable the spring 82 to urge the bleed valve 74 back against the
valve seat.
[0061] A thread lifting strip support 84 is located in the rear
suction cavity section 26. The support 84 is connected to the lower
body section 20 of the main body 12 so that it is moveable relative
to the lower body section 20, and thus relative to the rear suction
cavity section 26 and its suction opening 30. In this example, the
support 84 is connected to the front wall 50 of the rear suction
cavity section 26. The support 84 comprises a pair of arms 86
extending outwardly from a main body of the support 84, and which
extend through apertures formed in the front wall 50. The arms 86
are provided with recesses for receiving shafts 88 connected to the
front wall 50. The arms 86 are connected to the front wall 50 in a
snap-fit which allows the arms 86 to pivot about an axis A passing
longitudinally through the shafts 88. The length of the arms 86 is
selected to allow the support 84 to be spaced from the front wall
50 so that the rear suction cavity section 26 extends about the
main body of the support 84.
[0062] The main body of the support 84 has a recessed portion 90 to
which a first thread lifting strip 92 is attached, for example
using an adhesive. The thread lifting strip 92 is in the form of an
elongate strip or pad, having a lower surface comprising short
tufts of relatively stiff bristles or fibres. The fibres of the
thread lifting strip 92 are aligned in a common direction, which in
this example is inclined downwardly and away from the front wall 50
of the rear suction cavity section 26. The recessed portion 90 of
the support 84 defines, with the lower surface 94 of the support
84, a front edge 96 and a rear edge 98 of the support 84. The rear
edge 98 protrudes downwardly beyond the front edge 96. In a lowered
position L of the support, as illustrated in FIGS. 4 and 5, the
rear edge 98 is located substantially in the plane P.sub.1
containing the working edges 42, 44, 56, 58 of the suction openings
28, 30. The support 84 includes a stop member 100 which inhibits
movement of the support 84 downwardly beyond this lowered position
L. The stop member 100 is located on one of the arms 86 of the
support 84, and is arranged to engage an abutment surface 102
located on the front wall 50 of the rear suction cavity section 26.
A similar stop member 100 may be provided on the other arm 86.
[0063] The support 84 can move upwardly from this lowered position
L to a raised position R, illustrated with dashed lines in FIGS. 4
and 5, through pivoting movement of the support 84 about the axis
A. The support 84 is biased towards its lowered position L by a
torsion spring 104. The torsion spring 104 has a first end which
engages the front wall 50, and a second end which engages part of
the support 84, preferably one of the arms 86 of the support 84, to
urge the support 84 towards its lowered position. A second torsion
spring 104 may be provided for engaging the other arm 86 of the
support 84.
[0064] A second thread lifting strip 106 is attached to the bottom
surface 32 of the lower body section 20 of the main body 12. In
this example, the second thread lifting strip 106 is attached to a
trailing section 108 of the bottom surface. The trailing section
108 extends rearwardly from the rear working edge 58 of the suction
opening 30, and is inclined upwardly relative to the plane P.sub.1
containing the working edges 42, 44, 56, 58. The second thread
lifting strip 106 extends substantially the entire width of the
main body 12. The fibres of the second thread lifting strip 106 are
aligned so that they are inclined towards the rear working edge 58
of the suction opening 30.
[0065] In use, the cleaner head 10 is connected to a vacuum
cleaning appliance which generates a suction airflow. With the
cleaner head 10 positioned on a carpeted floor surface to be
cleaned, the user sequentially pushes and pulls the wand to move
the cleaner head 10 forwards and backwards over the carpet. During
each forward stroke of the cleaner head 10, the front working edges
42, 56 move over the fibres of the carpet in such a direction that,
as the fibres pass beneath the front working edges 42, 56 they
enter one of the suction cavity sections 24, 26. As these front
working edges 42, 56 move over the fibres, the upper ends of the
fibres are deflected in a forwards direction under the action of a
downwards force applied by the front working edges 42, 56. Once the
front working edges 42, 56 have moved beyond the deflected fibres,
the deflected fibres spring back into one of the suction cavity
sections 24, 26. This rapid movement of the fibres causes dirt and
dust to be dislodged from between the fibres and into the suction
cavity sections 24, 26. Dirt and dust entering the front suction
cavity section 24 becomes entrained within a first air flow drawn
under the front working edge 42 and into the front suction cavity
section 24, whereas dirt and dust entering the rear suction cavity
section 26 becomes entrained within a second air flow which passes
through the channel 54 and under the front working edge 56 to enter
the rear suction cavity section 26. The dirt-bearing first air flow
passes through the intermediate channels 62 to join the
dirt-bearing second air flow within the rear suction cavity section
26. The air flows leave the rear suction cavity section 26 through
the air outlet 64.
[0066] During each reverse stroke of the cleaner head 10, the rear
working edges 44, 58 move over the fibres of the carpet in such a
direction that, as the fibres pass beneath the rear working edges
44, 58 they enter one of the suction cavity sections 24, 26. As the
rear working edges 44, 58 move over the fibres, the upper ends of
the fibres are deflected in a backwards direction under the action
of a downwards force applied by the rear working edges 44, 58. Once
the rear working edges 44, 58 have moved over these deflected
fibres, the deflected fibres spring back into one of the suction
cavity sections 24, 26. This rapid movement of the fibres causes
dirt and dust to be dislodged from between the fibres and into the
suction cavity sections 24, 26. Dirt and dust entering the front
suction cavity section 24 becomes entrained within a first air flow
which passes through the channel 54 and under the rear working edge
44 to enter the front suction cavity section 24, whereas dirt and
dust entering the rear suction cavity section 26 becomes entrained
within a second air flow which is drawn under the rear working edge
58 and into the rear suction cavity section 26. Again, the
dirt-bearing first air flow passes through the intermediate
channels 62 to join the dirt-bearing second air flow within the
rear suction cavity section 26. The air flows leave the rear
suction cavity section 26 through the air outlet 64.
[0067] Thus, during each of the forwards and backwards strokes of
the cleaner head 10 over the carpet the working edges 42, 44, 56,
58 act to dislodge dirt and debris from between the fibres of the
carpet. During each of these strokes, the thread lifting strips 92,
106 act to remove lint, in the form of threads, hair and the like,
from the surface of the carpet. As discussed above, the first
thread lifting strip 92 is mounted on a support 84 located within
the rear suction cavity section 26. As the cleaner head 10 is
manoeuvred over the carpet, a carpet "hill" is pulled into each of
the suction cavity sections 24, 26 as a result of the reduced air
pressure within those suction cavity sections 24, 26. The carpet
hill drawn into the rear suction cavity section 26 engages and is
placed in close contact with the first thread lifting strip 92. As
the support 84 is moveable relative to the rear suction cavity
section 26, the force acting between the carpet and the first
thread lifting strip 92 as the cleaner head 10 is moved over the
carpet is not so great as to diminish significantly the force
applied to the carpet fibres by the working edges 42, 44, 56, 58,
while the action of the torsion springs 104 maintains the close
contact between the carpet and the first thread lifting strip
92.
[0068] The fibres of the first thread lifting strip 92 are aligned
so that, with each reverse stroke of the cleaner head 10, lint
located on the carpet hill is collected on the surface of the first
thread lifting strip 92. The accumulated lint can be released from
the first thread lifting strip 92 with a forward stroke of the
cleaner head 10, to become entrained within the air flow passing
through the rear suction cavity section 26. The release of the
collected lint from the first thread lifting strip 92 can be
assisted by the rear support edge 98; as the cleaner head 10 is
moved in a forward direction the collected lint can become trapped
or pinched between the rear support edge 98 and the carpet, and
this can result in the collected lint being torn from the first
thread lifting strip to become entrained within the air flow
passing through the rear suction cavity section 26.
[0069] The fibres of the second thread lifting strip 106 are
aligned so that, with each forward stroke of the cleaner head 10,
lint located on the carpet directly behind the rear suction cavity
section 26 can become collected on the surface of the second thread
lifting strip 106. The accumulated lint can be released from the
second thread lifting strip 106 with a reverse stroke of the
cleaner head 10. This released lint can either become entrained
within the second air flow passing beneath the rear working edge 58
of the rear suction cavity section 26, or remain on the surface of
the carpet to be subsequently drawn into the cleaner head 10.
[0070] FIGS. 6 to 9 are external views of a second example of a
cleaner head 110 for a vacuum cleaning appliance. Similar to the
first example, the cleaner head 110 comprises a main body 112 and a
pair of wheels 114 arranged to allow the cleaner head 110 to be
manoeuvred over a floor surface. The main body 112 comprises a
lower body section 116 pivotably connected to an upper body
section. The upper body section comprises a front section 118 to
which the lower body section 116 is connected, and a rear section
120 pivotably connected to the front section 118. The wheels 114
are connected to the rear section 120 of the main body 112. The
rear section 120 comprises a connector 122 having an open end which
is connectable to a wand or hose of a vacuum cleaner.
[0071] In this second example, the lower body section 116 defines a
single suction cavity 124 of the cleaner head 110. In use, the
suction cavity faces the floor surface to be cleaned and admits
dirt-bearing air from the floor surface into the cleaner head 110.
The suction cavity 124 extends substantially fully across the lower
body section 116. The suction cavity 124 has a downwardly-directed
suction opening 126 through which a dirt-bearing air flow enters
the suction cavity 124. The suction opening 126 is defined by the
bottom surface of the lower body section 116. The suction opening
126 is delimited by a relatively long front wall 128, a relatively
long rear wall 130, and two relatively short side walls 132, 134
which extend between the ends of the relatively long walls 128,
130. A front working edge 136 of the suction opening 126 is defined
at the intersection between the bottom surface of the lower body
section 116 and the front wall 128, and a rear working edge 138 of
the suction opening 126 is defined at the intersection between the
bottom surface and the rear wall 130. The working edges 136, 138
are substantially co-planar and located within a plane containing
the suction opening 126. The suction cavity 124 comprises a
centrally located air outlet 140 which conveys a dirt-bearing air
flow into an air passageway 142 extending through the lower body
section 116. The upper body section comprises a conduit 144 for
conveying the dirt-bearing air flow from the air passageway 142 to
the connector 122.
[0072] In this second example, the cleaner head 110 comprises a
frame or cover 146 extending over and around the lower body section
116. The frame 146 bears a set of bristles 148 which extend
downwardly around the lower periphery of the lower body section
116. The cleaner head 110 comprises a mechanism 150 for allowing
the user to move the frame 146 between a lowered position, as
illustrated in FIGS. 6 to 12, in which the lower ends of the
bristles are located beneath the plane containing the suction
opening 126, and a raised position in which the lower ends of the
bristles are located beneath this plane. When the frame 146 is in
its lowered position, the cleaner head 110 is in a configuration
for cleaning a hard floor surface. The working edges 136, 138 are
spaced from the hard floor surface to prevent those edges from
scratching or otherwise marking the hard floor surface. When the
frame 146 is in its raised position, the cleaner head 110 is in a
configuration for cleaning a carpeted surface, as the working edges
136, 138 may be brought into contact with the fibres of the
carpet.
[0073] A thread lifting strip support 152 is located in the suction
cavity 124. The support 152 is connected to the lower body section
116 of the main body 112 so that it is moveable relative to the
lower body section 116, and thus relative to the suction cavity 124
and the suction opening 126. In this second example, the support
152 is connected to the front wall 128 of the suction cavity 124.
With reference also to FIG. 10, the support 152 comprises a pair of
arms 154 each extending outwardly from a respective end of a main
body of the support 152, and which extend through apertures formed
in the front wall 128. The arms 154 are provided with recesses for
receiving shafts 156 connected to the front wall 128. The arms 154
are connected to the front wall 128 in a snap-fit which allows the
arms 154 to pivot about an axis passing longitudinally through the
shafts 156 and which is parallel to the plane of the suction
opening 126. The length of the arms 154 is selected to allow the
support 152 to be spaced from the front wall 128 so that the
suction cavity 124 extends about the main body of the support
152.
[0074] As in the first example, the main body of the support 152
has a recessed portion 158 to which a first thread lifting strip
160 is attached, for example using an adhesive. The thread lifting
strip 160 is in the form of an elongate strip or pad, having a
lower surface comprising short tufts of relatively stiff bristles
or fibres. The fibres of the thread lifting strip 160 are aligned
in a common direction, which in this example is inclined downwardly
and away from the front wall 128 of the suction cavity 124. The
recessed portion 158 of the support 152 defines, with the lower
surface of the support 152, a front edge 162 and a rear edge 164 of
the support 152. The rear edge 164 protrudes downwardly beyond the
front edge 162. In this second example, in a lowered position of
the support 152, as illustrated in FIGS. 10 to 12, the rear edge
164 is located above the plane of the suction opening 126. The
support 152 includes a stop member 166 which inhibits movement of
the support 152 downwardly beyond this lowered position. The stop
member 166 is located on the main body of the support 152, and is
arranged to engage the front wall 128 of the suction cavity
124.
[0075] As in the first example, the support 152 can move upwardly
from this lowered position to a raised position through pivoting
movement of the support 152 relative to the front wall 128 of the
suction cavity 124. The support 152 is biased towards its lowered
position by a torsion spring 168. The torsion spring 168 has a
first end which engages the front wall 128, and a second end which
engages part of the support 152, preferably one of the arms 154 of
the support 152, to urge the support 152 towards its lowered
position. A second torsion spring may be provided for engaging the
other arm 154 of the support 152.
[0076] In this second example, the cleaner head 110 includes means
for inhibiting the wrapping of threads or hair around the support
152, in particular threads or hairs which have been collected in
such an orientation that their length extends generally along the
thread lifting strip 160. The means for inhibiting the wrapping of
threads or hair around the support 152 is located in a channel 170
extending between the front wall 128 and the main body of the
support 152. In this example, the means for inhibiting the wrapping
of threads or hair around the support 152 comprise a first set of
ribs 172 connected to the support 152 and which extend into the
channel 170 towards the front wall 128, and a second set of ribs
174 connected to the front wall 150 and which extend into the
channel 170 towards the support 152. Each rib of the first set of
ribs 172 is preferably located adjacent to one of the ribs of the
second set of ribs 174. The ribs provide a barrier along one side
of the support 152 which prevents the ends of threads captured by
the thread lifting strip 160 from wrapping around the support 152
without impeding significantly the flow of air through the channel
170 towards the outlet of the suction cavity 124.
[0077] A second thread lifting strip 176 is attached to the bottom
surface of the lower body section 116 of the main body 112. In this
example, the second thread lifting strip 176 is attached to a
trailing section of the bottom surface. The trailing section
extends rearwardly from the rear working edge 138 of the suction
opening 126, and is inclined upwardly relative to the plane
containing the working edges 136, 138. The second thread lifting
strip 176 extends substantially the entire width of the main body
112. The fibres of the second thread lifting strip 176 are aligned
so that they are inclined towards the rear working edge 138.
[0078] In use, the operation of the cleaner head 110 for cleaning a
carpeted floor surface, and so when the frame 146 is in its raised
position, is similar to that of the cleaner head 10. During each
forward stroke of the cleaner head 110, the front working edge 136
agitates the fibres of the carpet to cause dirt and dust to be
dislodged from between the fibres and into the suction cavity 124.
This dirt and dust becomes entrained within an air flow drawn under
the front working edge 136 into the suction cavity 124. During each
reverse stroke of the cleaner head 110, the rear working edge 138
agitates the carpet fibres to dislodge dirt and dust from between
the carpet fibres and into the suction cavity 124. This dirt and
dust becomes entrained within an air flow drawn under the rear
working edge 138 and into the suction cavity 124. The dirt-bearing
air flow leaves the suction cavity 124 through the air outlet 140,
and passes through the cleaner head 110 to the wand or hose of a
vacuum cleaner attached to the connector 122.
[0079] During each of these strokes, the thread lifting strips 160,
176 act to remove lint, in the form of threads, hair and the like,
from the surface of the carpet. As discussed above, the first
thread lifting strip 160 is mounted on a support 152 located within
the suction cavity 124. As the cleaner head 110 is manoeuvred over
the carpet, a carpet "hill" is pulled into the suction cavity 124
as a result of the reduced air pressure within the suction cavity
124. The carpet hill engages and is placed in close contact with
the first thread lifting strip 160. As the support 152 is moveable
relative to the suction cavity 124, the force acting between the
carpet and the first thread lifting strip 160 as the cleaner head
110 is moved over the carpet is not so great as to diminish
significantly the force applied to the carpet fibres by the working
edges 136, 138, while the action of the torsion spring 168
maintains the close contact between the carpet and the first thread
lifting strip 160.
[0080] The fibres of the first thread lifting strip 160 are aligned
so that, with each reverse stroke of the cleaner head 110, lint
located on the carpet hill is collected on the surface of the first
thread lifting strip 160. The accumulated lint can be released from
the first thread lifting strip 160 with a forward stroke of the
cleaner head 10, to become entrained within the air flow passing
through the suction cavity 124. The release of the collected lint
from the first thread lifting strip 160 can be assisted by the rear
support edge 164; as the cleaner head 110 is moved in a forward
direction the collected lint can become trapped or pinched between
the rear support edge 164 and the carpet, and this can result in
the collected lint being torn from the first thread lifting strip
160 to become entrained within the air flow passing through the
suction cavity 124.
[0081] The fibres of the second thread lifting strip 176 are
aligned so that, with each forward stroke of the cleaner head 10,
lint located on the carpet directly behind the suction cavity 124
can become collected on the surface of the second thread lifting
strip 176. The accumulated lint can be released from the second
thread lifting strip 176 with a reverse stroke of the cleaner head
110. This released lint can either become entrained within the air
flow passing beneath the rear working edge 138, or remain on the
surface of the carpet to be subsequently drawn into the cleaner
head 110.
* * * * *