U.S. patent application number 14/006057 was filed with the patent office on 2014-06-19 for vacuuming device comprising a vacuum cleaner and a bag filter.
This patent application is currently assigned to Eurofilters Holding N.V.. The applicant listed for this patent is Ralf Sauer, Jan Schultink. Invention is credited to Ralf Sauer, Jan Schultink.
Application Number | 20140165325 14/006057 |
Document ID | / |
Family ID | 45876674 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140165325 |
Kind Code |
A1 |
Sauer; Ralf ; et
al. |
June 19, 2014 |
Vacuuming Device Comprising a Vacuum Cleaner and a Bag Filter
Abstract
The invention relates to a vacuum-ceaning apparatus comprising a
vacuum cleaner and a filter bag made of non-woven fabric, wherein
the vacuum cleaner has a nominal electric input power of less than
1200 W, preferably less than 1100 W, more preferably less than 900
W, wherein the vacuum cleaner comprises a motor-fan unit and a
controlling device controlling the vacuum cleaner such that the
airflow is kept substantially constant at a value of at least 34
l/s, preferably substantially constant at a value of at least 37
l/s, more preferably substantially constant at a value of at least
40 l/s when the filter bag is loaded with DMT8 test dust analogous
to EN 60312, and wherein the filter bag is a disposable filter bag
made of non-woven fabric which has an airflow drop of less than
15%, preferably less than 10%, more preferably less than 5% in
tests demonstrating the reduction of the maximum airflow with a
partially filled dust container analogous to EN 60312.
Inventors: |
Sauer; Ralf; (Overpelt,
BE) ; Schultink; Jan; (Overpelt, BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sauer; Ralf
Schultink; Jan |
Overpelt
Overpelt |
|
BE
BE |
|
|
Assignee: |
Eurofilters Holding N.V.
Overpeit
BE
|
Family ID: |
45876674 |
Appl. No.: |
14/006057 |
Filed: |
March 20, 2012 |
PCT Filed: |
March 20, 2012 |
PCT NO: |
PCT/EP2012/001226 |
371 Date: |
February 3, 2014 |
Current U.S.
Class: |
15/339 ;
15/347 |
Current CPC
Class: |
A47L 9/14 20130101; A47L
9/2842 20130101; A47L 9/19 20130101; A47L 9/0072 20130101; A47L
9/2857 20130101 |
Class at
Publication: |
15/339 ;
15/347 |
International
Class: |
A47L 9/14 20060101
A47L009/14; A47L 9/28 20060101 A47L009/28; A47L 9/19 20060101
A47L009/19 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2011 |
DE |
10 2011 014 682.2 |
Claims
1. Vacuum-cleaning apparatus comprising a vacuum cleaner and a
filter bag made of non-woven fabric, wherein the vacuum cleaner has
a nominal electric input power of less than 1200 W the vacuum
cleaner comprises a motor-fan unit and a controlling device
controlling the vacuum cleaner such that the airflow is kept
substantially constant at a value of at least 34 l/s, when the
filter bag is loaded with DMT8 test dust analogous to EN 60312, and
the filter bag is a disposable filter bag made of non-woven fabric
which has an airflow drop of less than 15 in tests demonstrating a
reduction of a maximum airflow with a partially filled dust
container analogous to EN 60312.
2. The apparatus according to claim 1, wherein the controlling
device is an electronic controlling device adapted to control an
electric input power of the motor-fan unit,
3. The apparatus according to claim 2, wherein an increase of the
input power of the motor-fan unit required to maintain the
substantially constant airflow when the filter bag is loaded with
DMT8 dust analogous to EN 60312 is not more than 35% in relation to
the input power of the motor-fan unit when the filter bag is
empty.
4. The apparatus according to claim 1, wherein the motor-fan unit
comprises a reluctance motor.
5. The apparatus according to claim 1, wherein the controlling
device comprises a throttle valve provided to control the airflow
to be substantially constant.
6. The apparatus according to claim 1, wherein the controlling
device is adapted such that a negative pressure downstream of the
filter bag is used as a controlled variable.
7. The apparatus according to claim 1, wherein the controlling
device is adapted such that a negative pressure upstream of the
filter bag is used as a controlled variable,
8. The apparatus according to claim 1, wherein the controlling
device is provided such that the flow rate measured at an optional
position in the flow path is used as a controlled variable.
9. The apparatus according to claim 1, wherein the filter bag is a
flat bag.
10. The apparatus according to claim 1, wherein the filter bag
comprises at least one surface fold.
11. The apparatus according to claim 1, wherein the motor-fan unit
is adapted such that the vacuum cleaner generates, with a filter
bag being inserted, with an orifice 0 a negative pressure between
30 kPa and 6 kPa, and with an orifice 8 (40 mm) an airflow of more
than 50 l/s.
12. The apparatus according to claim 1, wherein the vacuum cleaner
has, with an orifice 8 (40 mm), a rate of airflow of more than 250
W.
13. The apparatus according to claim 1, wherein the motor-fan unit
has, with an orifice 8 (40 mm), an efficiency according to EN 60312
of at least 20%.
14. The apparatus according to claim 1, wherein the vacuum cleaner
comprises a filter bag change indicator indicating if, during the
vacuum-cleaning, the airflow drops under a substantially constant
value for a predetermined period.
15. The apparatus according to claim 1, wherein the filter bag has
a volume in a range of 1.5 l to 8 l measured according to EN
60312.
16. The apparatus according to claim 1, wherein the vacuum cleaner
has a nominal electric input power of less than 900 W.
17. The apparatus according to claim 1, wherein the airflow is kept
substantially constant at a value of at least 40 l/s.
18. The apparatus according to claim 1, wherein the disposable
filter bag made of non-woven fabric which has an airflow drop of
less than 5% in tests demonstrating the a reduction of the a
maximum airflow with a partially filled dust container analogous to
EN 60312.
19. The apparatus according to claim 3, wherein the increase of the
input power of the motor-fan unit required to maintain the
substantially constant airflow when the filter bag is loaded with
DIMT8 dust analogous to EN 60312 is not more than 15% in relation
to the input power of the motor-fan unit when the filter bag is
empty.
20. The apparatus according to claim 4, wherein the motor-fan unit
comprises a switched reluctance motor.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a vacuum-cleaning apparatus
comprising a vacuum cleaner and a filter bag made of non-woven
fabric.
DEFINITIONS
[0002] The description of the prior art and the invention is based
on the standards, definitions and measuring methods specified
below:
[0003] EN 60312: EN 60312 denotes the standard in version EN
60312:1998 +A1:2000 A2:2004.
[0004] EN 60335: EN 60335 denotes the standard in version EN
60335-2-22010.
[0005] Determination of air data: The air data of a vacuum cleaner
are determined according to EN 60312, chapter 2.8. The measuring
device B according to chapter 5.2.8 is used. if motor-fan units sob
are measured, viz. without a vacuum cleaner case, the measuring
device B is applied equally.
[0006] The measurement of the reduction of the maximum airflow with
a partially filled dust container according to chapter 2.9 is
carried out with orifice 8 (40 mm).
[0007] Nominal electric input power of a vacuum cleaner: The input
power of a vacuum cleaner is determined according to EN 60335.
According to EN 60335 and EN 60312 the input power is denoted with
P.sub.1. According to EN 60335 the nominal input power is the
arithmetic mean from the maximum input power and the minimum input
power. The maximum input power is measured at the highest airflow
(open airflow), and the minimum input power at an airflow of 0 l/s
(sealed suction), Electromotively driven attachments such as
brushes and the like are disregarded in the input power
determination.
[0008] Airflow: According to EN 60312 the airflow is determined
using the version B measuring chamber. In the prior art this
airflow is often also referred to as volume flow or suction
airflow.
[0009] Airflow drop, constant airflow: The airflow drop is
determined in usability tests of vacuum cleaners following EN 60312
(chapter 2.9 of this standard) using the version B measuring
chamber. Deviating from the standard the reduction of the airflow
is tested by vacuuming 400 g of DMT8 test dust in 50 g portions,
provided the highest usable volume of the filter bag (see chapter
2.7 of this standard) is above 2 l. The three conditions described
in chapter 2.9.1.3 of the standard as leading to the
discontinuation of the test are disregarded. Chapter 2.9.1.3 is
relevant for volumes below 2 l. This method of measuring the
airflow drop thus modified as against the EN 60312 standard will be
referred to as "analogous to EN 60312" in the present description
and the present patent clairns.
[0010] A constant airflow q is assumed if the airflow q.sub.c is
not lower after the vacuuming of the DMT8 test dust than the
airflow q.sub.max with an empty dust container (cyclone vacuum
cleaner), respectively empty filter bag (bag vacuum cleaner).
Typically, 400 g of DMT8 test dust are vacuumed in 50 g portions.
The test is performed with orifice 8 (40 mm). With regard to the
definition of the term orifice reference is made to EN 60312,
chapter 5.2.8.2. This orifice corresponds to a relatively open
floor nozzle. The airflow drop is calculated according to:
Airflow drop [%]=((q.sub.max.q.sub.c)/q.sub.max).times.100 [0011]
q.sub.max=maximum airflow with empty dust container [0012]
q.sub.c=maximum airflow with partially filled dust container
[0013] However, in the present description of the prior art and the
invention a substantially constant airflow does not mean that the
airflow remains constant in different working situations, e.g. the
vacuuming of carpeted floors, respectively hard floor surfaces, or
the vacuuming with accessory nozzles. The different orifice areas
of these nozzles and the differently strong reduction of this
orifice area on different floor coverings result in different
airflows, depending on the working situation. With respect to EN
60312 this would correspond to a test with different orifices, with
orifice 0 corresponding to a state with a dogged nozzle, Orifice 9
(50 mm) corresponds to a nearly unobstructed inflow. Current floor
nozzles typically have an operating point in the range of orifice 7
(30 mm) to 8 (40 mm).
[0014] Power increase of the fan motor: The power increase of a fan
motor implies an increase of the input power [W]. In a universal
motor the power is adjusted by a phase-angle control, In the SR
motor (see below) the control voltage of the motor is
controlled,
[0015] SR motor: An SR motor is a switched reluctance motor which
is characterized by a simple and robust construction and high
possible speeds (>100,000 rpm). The torque is generated by the
reluctance force.
[0016] Flat bags: Rat bags as used in the present invention are
filter bags whose filter bag wall comprised of two individual
layers of a filter material with identical surface areas is formed
such that the two individual layers are connected to each other
only at their circumferential edges (the term identical surface
area does not preclude, of course, that the two individual layers
differ from each other by the fact that one of the layers includes
an inlet opening).
[0017] The connection of the individual layers may be realized by a
welding seam or adhesive seam along the total circumference of the
two individual layers. However, it may also be realized such that
one individual layer made of a filter material is folded about one
of its axes of symmetry while the other, open circumferential edges
of the so created two sub-layers are welded or bonded to each other
(so-called tubular bag). Thus, this type of manufacture requires
three welding or bonding seams. Two of those seams then form the
filter bag edge. The third seam may equally form a filter bag edge
or he on the filter bag surface.
[0018] Flat bags as used in the present invention may also comprise
so-called gussets. These gussets may be fully unfoldable. A flat
bag having such gussets is shown, for instance, in DE 20 2005 000
917 U1 (see FIG. 1 with folded gussets, and FIG. 3 with unfolded
gussets). Alternatively, the gussets may be welded to sections of
the circumferential edge. Such a flat bag is shown in DE 10 2008
006 769 A1 (see FIG. 1 thereof).
[0019] Surface folds: A filter bag whose filter bag wall comprises
surface folds is known per se from the prior art, e.g. from the
European patent application 10163483.2 (see in particular
[0020] FIG. 10a and FIG. 10b, respectively FIG. 11a and FIG. 11b
thereof). If the filter bag wall comprises a plurality of surface
folds this material is also called a pleated filter material. Such
pleated filter bag wags are shown in the European patent
application 10002964.4.
[0021] FIG. 1 and FIG. 2 show a cross-section of a filter bag
comprising a wall with two surface folds. Such surface folds
enlarge the filter surface of the filter bag so that a higher dust
absorption capacity of the filter bag, along with a high collection
efficiency and longer service life, is obtained (as compared with a
filter bag having same outer dimensions and without surface
folds).
[0022] FIG. 1 shows a filter bag 1 comprising a filter bag wall 10
with two surface folds 11 in the form of so-called dovetail folds.
The figure shows a cross-section of the filter bag through the
filter bag center. The longitudinal axes of the surface folds
accordingly extend in one plane which, again, extends perpendicular
to the plane of projection, and the surface folds extend at theft
longitudinal ends into the welding seams of the filter bag which
extend in parallel to the plane of projection and are positioned in
front of and behind the plane of projection. Thus, the strongest
unfolding of the surface folds is in the middle thereof. The filter
bag is here shown in a state in which the surface folds are already
unfolded to some extent.
[0023] FIG. 2 shows a filter bag 2 comprising a filter bag wall 20
with two surface folds 21 in the form of so-called triangular
folds. The figure shows a cross-section of the filter bag through
the filter bag center. The longitudinal axes of the surface folds
accordingly extend in one plane which, again, extends perpendicular
to the plane of projection, and the surface folds extend at theft
longitudinal ends into the welding seams of the filter bag which
extend in parallel to the plane of projection and are positioned in
front of and behind the plane of projection. Thus, the strongest
unfolding of the surface folds is in the middle thereof. The filter
bag is here shown in a state in which the surface folds are already
unfolded to some extent.
[0024] Apart from the surface folds illustrated in FIG. 1 and FIG.
2 surface folds having different shapes are feasible, too. It
should not be regarded as a limitation that the surface folds in
the embodiments of FIG. 1 and FIG. 2 extend perpendicular to a bag
edge. Of course, the surface folds may also extend at an angle to
the bag edges.
[0025] Suction power: The suction power is the product of negative
pressure [kPa] and airflow [l/s]. According to EN 60312 the suction
power is denoted with P.sub.2.
[0026] Efficiency: The efficiency of a vacuum cleaner or a
motor-fan unit is determined in accordance with EN 60312, chapter
2.8.3.
PRIOR ART
[0027] The requirements made on vacuum-cleaning apparatus have been
subject to considerable change in recent years.
[0028] One essential point expected by the users of vacuum-cleaning
apparatus is that the vacuum-cleaning apparatus produces a constant
airflow even as the dust load increases or, in other words, that
the vacuum-cleaning apparatus does not experience an airflow drop
as the dust load increases.
[0029] The study by "AEA Energy & Environment Group" on behalf
of the "European Commission Energy" for the definition of the
requirements on an eco design for vacuum cleaners demonstrates that
it would be desirable to limit the input power to below 1100 W in
the future for energy policy aspects. The users of vacuum cleaners
do expect, however, that the cleaning performance will not
significantly deteriorate as compared to vacuum-cleaning devices
with a substantially higher input power as are available
nowadays.
[0030] The customers' hygiene requirements on a vacuum-cleaning
apparatus relate no longer to a lowest possible dust emission of
the apparatus only, but also to the hygienic disposal of the
vacuumed dust.
[0031] In terms of the collection concept a difference is made
between vacuum cleaners without filter bags and vacuum cleaners
with filter bags. These apparatus each have typical advantages and
disadvantages.
[0032] Vacuum cleaners with filter bags are characterized by a high
airflow. However, as the filter bag is more and more loaded the
airflow drops more or less strongly. Approximately up to the year
2000 filter bags made of paper were primarily used. In tests
demonstrating the reduction of the maximum airflow with a partially
filled dust container analogous to EN 60312 such paper filter bags
show an airflow drop of about 80% (respectively 60% if an internal
tissue is used). After that, filter bags having non-woven fabric
inserts slowly began establishing themselves. Initially, filter
bags with non-woven fabric layers of a low dust storage capacity
were used (SMS filter bags). By introducing filter bags of
non-woven fabrics with a capacity layer it was possible to clearly
reduce this drop of the airflow (see EP 0 960 645). In tests
demonstrating the reduction of the maximum airflow with a partially
filled dust container analogous to EN 60312 such filter bags show
an airflow drop of approximately 30%. Further enhancements were
achieved by an advance filtration by loose fibers in the bag (DE 10
2007 060 747, DE 20 2007 010 692 and WO 2005/060807) or an advance
separation by a bag in the bag (WO 2010/000453, DE 20 2009 002 970
U1 and DE 20 2006 016 303 U1). Flow deflections and flow
distributions in the filter bag are proposed in EP 1 915 938, DE 20
2008 016 300, DE 20 2008 007 717 Ul (dust-storing liner), DE 20
2006 019 108 U1, DE 20 2006 016 304 Ul, EP 1 787 560 and EP 1 804
635. In tests demonstrating the reduction of the maximum airflow
with a partially filled dust container analogous to EN 60312 an
airflow drop of approximately 15% was achieved with such filter
bags. Thus, a further improvement of the suction power stability is
obtained. The European patent applications 10002964A, 10163463.2,
and 10163462.2 disclose an improved dust storage capability by
pleating the filter material or by providing so-called surface
folds. The European patent application 10009351.7 shows how the
suction power stability can be improved by an optimized positioning
of the bag in the vacuum cleaner. Thus, in the tests demonstrating
the reduction of the maximum airflow with a partially filled dust
container analogous to EN 60312 filter bags of this type show an
airflow drop of about 5%.
[0033] With regard to the hygienic disposal of the vacuumed dust,
holding plates were developed by means of which the filter bag,
prior to removing it from the vacuum cleaner, is tightly sealed
manually, semi-automatically or automatically. (e.g. EP 2 012
640).
[0034] Vacuum cleaners without bags--in particular cyclone vacuum
cleaners--are characterized by a substantially constant airflow as
the dust collecting container is loaded with dust. At first sight,
the constant airflow of a cyclone vacuum cleaner is an advantage,
compared to vacuum cleaners with filter bags which get clogged more
or less strongly as the load of the filter bag increases so that
the airflow is reduced correspondingly. However, this is bought by
a very high nominal electric input power of the cyclone vacuum
cleaners. This high input power is necessary owing to the high
losses brought about by the separating principle, namely the loss
for the maintenance of the high rotational speed of the dust-laden
air in the cyclone separator.
[0035] By combining a number of cyclone separators to multi-stage
cyclones it was attempted to increase the efficiency and the
separating efficiency (EP 0 042 723). With such vacuum-cleaning
apparatus an aelow of 33 l/s can be achieved. However, this is
opposed by a nominal electric input power of far more than 2000 W.
Cyclone vacuum cleaners having an electric input power of
approximately 1400 W allow the realization of an airflow of about
25 l/s.
[0036] With conventional vacuum-cleaning apparatus working with
filter bags, freshly inserted and empty, it is nowadays possible to
realize an airflow of approximately 40 l/s. Such vacuum cleaners
have a nominal input power of about 1300 W.
[0037] However, the airflow strongly decreases with the dust
loading, as can be seen in FIG. 3. FIG. 3 shows the reduction of
the airflow in response to the vacuumed amount of DMT8 dust
analogous to EN 60312 in known apparatus with filter bags (e.g.
Miele S5210 with a nominal electric input power of 2200 W and
different filter bags of a non-woven fabric) and without filter
bags (Dyson DC23 alergy with a nominal electric input power of 1400
W).
[0038] In addition to improvements of the filter bags approaches
have been made to realize a constant airflow in vacuum cleaners
with filter bags by means of an electronic control.
[0039] A vacuum-cleaning apparatus is described, for instance, in
U.S. Pat. No. 4,021,879, whose vacuum cleaner comprises a
controlling device controlling the vacuum-cleaning apparatus in
such a way that a substantially constant airflow is realized.
However, in this apparatus filter bags made of paper are used.
Owing to the great clogging tendency of filter bags made of paper
(about 80% airflow drop with 400 g of DMT8; inner tissues were not
used as yet at the publication date of U.S. Pat. No. 4,021,879) a
very broad control range has to be provided for the nominal
electric input power. Although a constant airflow is thus
theoretically realizable, same is very low. For this reason, this
concept was not pursued and, therefore, could not be implemented in
a product successful on the market.
DESCRIPTION OF THE INVENTION
[0040] Given the aforementioned disadvantages of the prior art the
invention is based on the object to provide a vacuum-cleaning
apparatus in which a constantly high airflow is realized despite a
low nominal electric input power.
[0041] This object is achieved by a vacuum-cleaning apparatus
comprising the features of patent claim 1, viz. by a
vacuum-cleaning apparatus comprising a vacuum cleaner and a filter
bag made of non-woven fabric, wherein the vacuum cleaner has a
nominal electric input power of less than 1200 W, preferably less
than 1100 W, more preferably less than 900 W, the vacuum cleaner
comprises a motor-fan unit and a controlling device controlling the
vacuum cleaner such that the airflow is kept substantially constant
at a value of at least 34 l/s, preferably substantially constant at
a value of at least 37 l/s, more preferably substantially constant
at a value of at least 40 l/s when the filter bag is loaded with
DMT8 test dust analogous to EN 60312, and the filter bag is a
disposable filter bag made of non-woven fabric which has an airflow
drop of less than 15%, preferably less than 10%, more preferably
less than 5% in tests demonstrating the reduction of the maximum
airflow with a partially filled dust container analogous to EN
60312.
[0042] The present invention is based on the concept that a
vacuum-cleaning apparatus with a filter bag, viz. an empty filter
bag, is operated with an input power that is adjusted to be lower
than the maximum power of the motor, so that the input power of the
motor can be increased in correspondence with the increasing load
of the filter bag. Surprisingly, it has shown that only with filter
bags having a clogging tendency of less than 15%, preferably less
than 10%, more preferably less than 5% a relatively small increase
of the input power of the motor is necessary to keep the airflow
constant on a level required for the efficient vacuum-cleaning,
i.e. at least 34 l/s. Only thus had it been possible to realize a
vacuum-cleaning apparatus that can provide a substantially constant
volume flow as the filter bag is continuously loaded, while, at the
same time, the maximum electric input power of the vacuum cleaner
remains below a predetermined value of 1200 W which is acceptable
from the viewpoint of power consumption.
[0043] According to a further development of the above-described
invention the vacuum-cleaning apparatus comprises an electronic
controlling device which is adapted to control the electric input
power of the motor-fan unit.
[0044] Preferably, the apparatus is then adapted such that the
increase of the input power of the motor-fan unit required to
maintain the substantially constant airflow when the filter bag is
loaded with DMT8 dust analogous to EN 60312 is not more than 35%,
preferably not more than 20%, and more preferably not more than 15%
in relation to the input power of the motor-fan unit when the
filter bag is empty. According to this embodiment it is possible to
realize vacuum-cleaning apparatus with a constant airflow, with a
vacuuming behavior as is known from today's non-controllable
apparatus, whereby the future energy policy standards can be
satisfied without problems.
[0045] Particularly suited for such an apparatus is a motor-fan
unit comprising a reluctance motor, preferably a switched
reluctance motor. Such motors are characterized in particular by
their robustness and durability.
[0046] Alternatively, according to another preferred further
development of the invention an apparatus may be provided wherein
the controlling device comprises a throttle valve which controls
the airflow to be substantially constant.
[0047] In both alternative further developments of the controlling
device the controlled variables may be the negative pressure
downstream of the filter bag, the negative pressure upstream of the
filter bag or the flow rate measured at an optional position in the
flow path. Optional combinations of these three quantities are also
feasible.
[0048] According to a preferred further development of all
inventions described above the filter bag may be provided in the
form of a flat bag. The flat bag shape is the most widely spread
shape for non-woven bags as bags of this shape are very easy to
manufacture. As opposed to the paper filter material used for paper
filter bags the non-woven fabric material is very hard to fold
permanently owing to the great resilience, so that the manufacture
of more complex bag shapes, such as block bottom bags or other bag
shapes having a bottom, is very complicated and expensive.
[0049] Particularly suited for use in the apparatus according to
the invention are vacuum cleaner bags having a pleated filter
material or surface folds. Such vacuum cleaner bags are
characterized by a particularly low airflow drop.
[0050] According to a preferred further development of the
invention the motor-fan unit is adapted such that the vacuum
cleaner generates, with a filter bao being inserted, with an
orifice 0 a negative pressure between 30 kPa and 6 kPa, preferably
a negative pressure between 20 kPa and 8 kPa, and more preferably a
negative pressure between 15 kPa and 8 kPa , and with an orifice 40
an airflow of more than 50 l/s, preferably more than 60 l/s, and
more preferably more than 70 l/s. This special characteristic of
the motor-fan unit differs from the characteristic of motor-fan
units used in conventional vacuum-cleaning apparatus in that the
latter generate an essentially higher negative pressure and an
essentially lower maximum airflow. Surprisingly, it has shown that
such motor-fan units are particularly energy-saving in use, yet
fulfill the requirements on a constant airflow of sufficient
power.
[0051] According to a particularly preferred further development of
all inventions described above the vacuum cleaner may have, with an
orifice 8 (40 mm), a rate of airflow of more than 250 W, preferably
of more than 300 W, more preferably of more than 350 W. If the
invention is constructed in this way a fully satisfying vacuuming
operation is ensured during the complete filling of the filter
bag.
[0052] Preferably, the motor-fan unit may have, with an orifice 8
(40mm), an efficiency according to EN 60335 of at least 20%,
preferably of at least 25%, and more preferably of at least 30%.
This further development of the invention results in a particularly
energy-saving vacuum-cleaning apparatus.
[0053] According to another further development of all inventions
described above the vacuum cleaner may comprise a filter bag change
indicator indicating it during the vacuum-cleaning, the airflow
drops under the substantially constant value for a predetermined
period, To this end, in particular the sensors can be applied that
are provided for measuring the controlled variables.
[0054] According to another preferred further development of the
above-described inventions the filter bag has a volume in a range
of 1.5 l to 8 l measured according to EN 60312. Filter bags of this
type are primarily used in vacuum cleaners that are constructed as
canister vacuum cleaners, hand-held vacuum cleaners, wetidry vacuum
cleaners or uprights for domestic use.
BRIEF DESCRIPTION OF THE FIGURES
[0055] The figures serve to explain the prior art and the
invention, in which
[0056] FIG. 1 and
[0057] FIG. 2 show filter bags according to the prior art with
surface folds;
[0058] FIG. 3 shows the reduction of the airflow for
vacuum-cleaning apparatus comprising vacuum cleaners and filter
bags according to the prior art as well as for a vacuum-cleaning
apparatus without filter bag according to the prior art;
[0059] FIG. 4 shows the air characteristics for a motor-fan unit
used in vacuum-cleaning apparatus according to the prior art;
[0060] FIG. 5 shows the air characteristics for a motor-fan unit
not used in vacuum-cleaning apparatus according to the prior art,
which is particularly suited for implementation in the present
invention; and
[0061] FIG. 6 shows the airflow and electric input power of a first
and a second embodiment of the present invention.
EMBODIMENTS OF THE INVENTION
[0062] FIG. 5 shows the characteristic curve of the motor-fan unit
according to an embodiment of the invention. Same is characterized
by a comparatively low maximum negative pressure with an orifice 0,
and a high volume flow with orifice 9 (50 mm). Especially with
orifice 0 a negative pressure of 14.3 kPa is obtained. Orifice 9
(50 mm) results in an airflow of 86.5 dm3/s. Hence, the
characteristic curve is very flat. With the maximum airflow the
motor consumes a power of 1240 W. The airflow power (product of
negative pressure and airflow) amounts to a maximum of 498 W with
orifice 7 (30 mm).
[0063] FIG. 4, however, shows the characteristic data for a
motor-fan unit as used according to the prior art in
vacuum-cleaning apparatus. With orifice 0 the motor-fan unit
generates a negative pressure of 35.8 kPa, orifice 9 (50 mm)
results in an airflow of 53.5 dm.sup.3/s. Hence, the characteristic
curve of the fan is very steep. With the maximum airflow the motor
consumes a power of 1900 W. The airflow power is 614 W. In the case
of greatly dogged paper filter bags such a design had been
necessary and sensible.
[0064] In the particularly preferred embodiment of the present
invention filter bags with surface folds are used as are described
in the above chapter DEFINITIONS.
[0065] The motor-fan unit shown in FIG. 5, in combination with a
filter bag having surface folds and an installation space adapted
to the filter bag, allows with a corresponding automatic
controlling of the airflow the realization of a vacuum cleaner that
achieves a high, constant airflow with an input power of below 1000
W. FIG. 6 shows the results for two embodiments according to the
present invention, both having in common that a very high, constant
airflow is achieved with a low electric input power.
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