U.S. patent application number 11/004035 was filed with the patent office on 2006-06-08 for regeneratable particle filter.
Invention is credited to Helmut Swars.
Application Number | 20060117743 11/004035 |
Document ID | / |
Family ID | 36572646 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060117743 |
Kind Code |
A1 |
Swars; Helmut |
June 8, 2006 |
Regeneratable particle filter
Abstract
The invention relates to a particle filter, especially for
exhaust gases of diesel-fuelled internal-combustion engines, with a
plurality of filter walls that can be flowed through by the fluid
for separating particles from a fluid stream, where the filter
walls form a filter body, where the filter displays an inflow side
and an outflow side and can be flowed through by the fluid to be
cleaned in one direction of flow. In order to create a particle
filter that can be regenerated quickly and easily, flow ducts for a
purging fluid are provided in a direction transverse to the
direction of flow of the fluid to be cleaned, extending through it
and having a purging fluid inlet opening and a purging fluid outlet
opening, through which the particles retained by the filter walls
can be discharged from the filter body through the purging fluid
flow ducts by means of the purging fluid.
Inventors: |
Swars; Helmut; (Bergisch
Gladbach, DE) |
Correspondence
Address: |
GROSSMAN, TUCKER, PERREAULT & PFLEGER, PLLC
55 SOUTH COMMERICAL STREET
MANCHESTER
NH
03101
US
|
Family ID: |
36572646 |
Appl. No.: |
11/004035 |
Filed: |
December 3, 2004 |
Current U.S.
Class: |
60/297 |
Current CPC
Class: |
F01N 3/0233 20130101;
F01N 3/0296 20130101; F01N 3/029 20130101 |
Class at
Publication: |
060/297 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Claims
1. Particle filter, especially for exhaust gases of diesel-fuelled
internal-combustion engines, with a plurality of filter walls that
can be flowed through by the fluid for separating particles from a
fluid stream, where the filter walls form a filter body, where the
filter displays an inflow side and an outflow side and can be
flowed through by the fluid to be cleaned in one direction of flow,
characterized in that, in a direction transverse to the direction
of flow of the fluid to be cleaned, flow ducts for a purging fluid
are provided, extending through it and having a purging fluid inlet
opening and a purging fluid outlet opening, through which the
particles retained by the filter walls can be discharged from the
filter body through the purging fluid flow ducts by means of the
purging fluid.
2. Particle filter according to claim 1, characterized in that one
or both openings of the purging fluid inlet opening and the purging
fluid outlet opening are each located on sides of the particle
filter other than the inflow side and the outflow side of the
filter body for the fluid to be cleaned.
3. Particle filter according to claim 1, characterized in that,
over part or all of the length of the filter body, the flow ducts
for fluid to be cleaned are of slit-like design, at least
essentially over the full width of the filter body.
4. Particle filter according to claim 1, characterized in that the
filter walls consist of a fabric that can be structured by
deformation, where the plurality of filter walls of the filter, or
of a filter segment, is formed by a continuous strip of filter
material, which is deposited to create a three-dimensional body,
forming deflection areas in the process.
5. Particle filter according to claim 4, characterized in that the
inlet opening and the outlet opening for the purging fluid are
provided on side surfaces of the particle filter that are bordered
by the deflection areas of the filter material strip on both
sides.
6. Particle filter according to claim 1, characterized in that feed
lines are provided, which, referred to the direction of flow of the
fluid to be cleaned, supply the purging fluid laterally to the
slit-like areas of the fluid ducts, or in that purging fluid
discharge lines are provided, which discharge the purging fluid
laterally from the slit-like ducts for the fluid to be cleaned, or
in that both types of lines are provided.
7. Particle filter according to claim 1, characterized in that the
purging fluid flow ducts merge into and emerge from slit-like areas
of the flow ducts for fluid to be cleaned that extend at least
essentially over the full length and width of the filter body.
8. Particle filter according to claim 1, characterized in that the
outflow-side flow ducts for fluid to be cleaned are at least
partially isolated from the purging fluid flow ducts.
9. Particle filter according to claim 8, characterized in that the
filter walls consist of a deformable material, in that edge areas
of the filter body constructed of the filter walls are folded over
in such a way that they form purging fluid inlets into flow ducts
that are open on the inflow side in relation to the fluid to be
cleaned, and at least partially seal flow ducts open on the outflow
side in relation to the cleaned fluid for the purging fluid.
10. Particle filter according to claim 1, characterized in that
stiffening elements are provided on the filter body, on the purging
fluid inlet, on the purging fluid outlet, or on both.
11. Particle filter according to claim 1, characterized in that a
particle accumulator is provided, as well as feed lines for passing
the particle-laden purging fluid stream leaving the filter body to
the particle accumulator, in which the particles discharged from
the filter body in the purging fluid stream accumulate.
12. Particle filter according to claim 1, characterized in that a
return line is provided, which feeds fluid discharged from the
filter body and at least partly stripped of particles back to the
purging fluid inlet.
13. Particle filter according to claim 1, characterized in that a
heating device is provided for heating the purging fluid supplied
to the purging fluid inlet opening.
14. Particle filter according to claim 1, characterized in that a
regeneration control device is provided for controlling
regeneration of the filter by purging of the inflow-side filter
chambers with purging fluid, and in that sensors are provided on
the filter for detecting parameters relating to the need for
regeneration, or the implementation of regeneration, or both.
15. Particle filter according to claim 1, characterized in that a
temperature sensor is provided for measuring the temperature of the
filter body, or for measuring fluids passing through the filter
body, and in that a purging fluid feed device is provided, which
controls the purging fluid supply as a function of the temperature
measured by the temperature sensor.
16. Particle filter according to claim 1, characterized in that the
regeneration control device is configured to perform regeneration,
which comprises the step of purging the filter chambers with
purging fluid, while a device or system generating the
particle-laden fluid stream continues to operate, if necessary.
17. Particle filter, especially for exhaust gases of diesel-fuelled
internal-combustion engines, with a plurality of filter walls that
can be flowed through by the fluid for separating particles from a
fluid stream, where the filter walls form a filter body, where the
filter displays an inflow side and an outflow side and can be
flowed through by the fluid to be cleaned in one direction of flow,
characterized in that, in a direction transverse to the direction
of flow of the fluid to be cleaned, continuous flow ducts for a
purging fluid are provided, extending through it and having a
purging fluid inlet opening and a purging fluid outlet opening,
through which the particles retained by the filter walls can be
discharged from the filter body through the purging fluid flow
ducts by means of the purging fluid, and in that the purging fluid
inlet opening and the purging fluid outlet opening merge into and
emerge from laterally open areas of slit-like flow ducts or filter
pockets, through which fluid to be cleaned flows through the filter
body in the direction of the outflow side.
18. Device or system generating particle-laden fluid, with a
particle filter according to claim 1, where at least one or more of
the following elements of a regeneration device, selected from
particle accumulator, heating device for heating purging fluid,
regeneration control device and temperature sensor, are permanently
provided on the device or system.
Description
[0001] The invention relates to a particle filter, especially for
exhaust gases of diesel-fuelled internal-combustion engines, with a
plurality of filter walls to be flowed through by the fluid for
separating particles from a fluid stream, where the filter displays
an inflow side and an outflow side and can be flowed through by the
fluid in one direction of flow.
[0002] Particle filters of this kind are known in a wide variety of
embodiments. The regeneration of particle filters of this kind,
especially when used as soot filters in the automotive sector, is
relatively complex and requires the vehicle to spend a period of
time in a workshop. For regeneration, the filter is initially burnt
out in order to preferably incinerate all constituents, one area of
the filter first being heated to the necessary temperature so that
the glowing area then spreads independently through the filter,
ultimately encompassing the entire filter volume. The ash is
subsequently blown out of the filter in the direction opposite to
that of the fluid to be cleaned. In this context, regeneration of
the filter must be carried out on a separate regeneration bench in
order to perform process control, to generate the high pressure for
the purging gas, which is forced through the filter on the exhaust
side, and to collect the remaining ash.
[0003] The object of the invention is to create a particle filter
in which regeneration can be performed more simply and, possibly,
more quickly.
[0004] This object is solved by providing a particle filter in
which the purging fluid stream is passed in a direction transverse
to the direction of flow of the fluid to be cleaned, to which end
flow ducts for the purging fluid are provided that extend over
part, or essentially all, of the width of the filter body. The
filter body can, for example, be constructed of filter walls
stacked in a preferred direction, as a result of which cubic or
prismatic filter bodies, in particular, can be constructed, or also
of filter walls arranged radially about an axis, as a result of
which cylindrical or semi-cylindrical filter bodies can be
created.
[0005] Owing to the purging fluid being passed in a stream
transverse to the fluid to be cleaned, regeneration can be
performed with a relatively low purging fluid pressure and, where
appropriate, also during continuing operation of the device or
system generating the particle-laden exhaust-gas stream, since the
purging fluid no longer has to work against the pressure of the
fluid to be cleaned, or the device or system does not have to be
shut down beforehand. As a result of this, regeneration can, for
example, be performed on the respective motor vehicle independently
of a workshop. Further, the purging fluid stream can preferably
enter into laterally open flow ducts or filter pockets for the
fluid to be cleaned, this avoiding a pressure loss of the purging
fluid, at least on the inflow side, since it no longer has to flow
into the filter body through a particle-tight filter wall. Further,
the purging process can be performed particularly effectively owing
to the fact that the purging fluid is passed through flow ducts
extending virtually over the entire width of the filter body.
Further, owing to the assistance of the purging fluid stream
transverse to the direction of flow of the fluid to be cleaned, the
heating phase for incinerating the filter residue can be carried
out particularly easily, since burning out is now no longer impeded
by filter walls. This greatly facilitates regeneration of the
particle filter as a whole.
[0006] The purging fluid flow ducts are preferably designed to
extend continuously through the filter body.
[0007] Particularly preferably, slit-like ducts are provided for
the fluid to be cleaned, extending over essentially the full length
of the filter body in the direction of flow and/or its width, this
also permitting particularly effective regeneration.
[0008] The mean slit height of the purging fluid ducts transverse
to the direction of flow of the fluid to be cleaned can be
.gtoreq.10%, preferably .gtoreq.25% to 50%, particularly preferably
.gtoreq.75% or approx. 100% of the mean or maximum spacing of the
filter walls in their stacking direction. In this context, the term
"stacking direction" refers merely to the succession of filter
walls, and is independent of the manufacturing process, meaning
that it also encompasses cylindrical filter bodies in which the
filter walls follow on from each other in the circumferential
direction. In the case of cylindrical filter bodies, the mean or
maximum filter wall spacing at the level of half the filter
diameter can be used accordingly.
[0009] It goes without saying that the duct or slit height of the
filter pockets, which are formed by adjacent filter walls and
through which the fluid to be cleaned flows into the filter body,
can be constant in the direction of flow, or can increase or
decrease towards the outflow end.
[0010] Especially if they are of slit-like design, the flow ducts
for the fluid to be cleaned preferably display a height a >0 at
the outflow end, for example .gtoreq.10%, preferably .gtoreq.25% to
50%, particularly preferably .gtoreq.75% of the mean or maximum
height of the flow ducts or filter pockets in the direction of
flow.
[0011] A particularly simple design of a filter body is obtained if
the latter consists of a strip of filter material deposited in
meandering fashion, as a result of which the filter can be
manufactured not only inexpensively, but also with great tightness
and high stability, especially also when exposed to varying thermal
and/or mechanical loads. Therefore, the deflection areas preferably
display a certain web height in order to already create a certain
slit height in the deflection areas. The above data for height a of
the flow ducts or filter pockets on the outflow side can apply
accordingly to the web height.
[0012] The purging fluid inlet opening is preferably located on a
side of the filter body other than the inflow and outflow side of
the filter, preferably on a side surface of the filter. Further,
the purging fluid outlet opening is preferably located on an outer
surface of the filter other than the inflow and outflow side of the
filter for the fluid to be cleaned. In particular, the purging
fluid inlet opening and purging fluid outlet opening can be located
on opposite sides of the filter, particularly each on a lateral
side surface of the filter, without being limited to this. Where
appropriate, either the purging fluid inlet opening or the purging
fluid outlet opening can also be located on the inflow side of the
filter body, or identical to the inflow opening for the fluid to be
cleaned.
[0013] The purging fluid duct preferably extends through the filter
in such a way that it covers the entire filter over the shortest
possible flow path in a direction transverse to the direction of
flow of the fluid to be cleaned.
[0014] Preferably, each of the filter pockets, which are open on
the inflow side relative to the fluid to be cleaned and are formed
by opposite filter walls, is assigned a purging fluid flow duct, in
which the purging fluid can pass through the filter transverse to
the direction of flow of the fluid to be cleaned.
[0015] The purging fluid is preferably fed into laterally open
areas of the flow ducts or filter pockets for the fluid to be
cleaned, which can, in particular, be of slit-like design in the
area of the purging fluid inflow and/or outflow opening. The inflow
and/or outflow areas for the purging fluid can also display a lower
flow resistance than the filter walls, meaning that, for example,
wide-meshed structures with only little flow resistance can be
provided in the specified areas, e.g. in order to stabilize the
filter walls. The purging fluid inlet into the filter body can thus
also be fully permeable to particles--at least during purging with
purging fluid.
[0016] The transverse direction in which the purging fluid is
passed relative to the direction of flow of the fluid to be cleaned
can, in particular, be essentially orthogonal to the latter. It
goes without saying that the purging fluid flow ducts can also
display a different orientation and, for example, be arranged at an
angle to the flow ducts for the fluid to be cleaned. The purging
fluid inlets and outlets can be located opposite each other on the
filter body, although they can also be offset relative to each
other in the longitudinal direction of the latter.
[0017] The purging fluid flow ducts can also display certain
ramifications. Thus, if the filter body is constructed of
structured filter walls arranged inversely to each other, for
example, such that the crests and valleys of adjacent filter walls
face each other, purging fluid flow ducts can be provided in this
way, or can display a greater height if the crests and/or valleys
each display indentations, enlarging the distance between them.
This also makes it possible to create ramified purging fluid flow
ducts.
[0018] Particularly preferably, the purging fluid flow ducts cross
slit-like areas of the flow ducts for fluid the to be cleaned that
extend at least essentially over the entire width of the filter
body, i.e. the fluid is passed through slit-like ducts of this
kind, transversely to the direction of flow of the fluid to be
cleaned. In this context, the purging fluid can be fed to and
discharged from the filter body at the same slit-like flow ducts on
opposite sides of the filter body, to which end appropriately
designed feed lines/discharge lines are provided.
[0019] The width of the purging fluid inlets and outlets can extend
over only a relatively small extension of the filter body, e.g.
only over less than 1/5 or 1/10 of its length, although the width
of the purging fluid flow ducts can nevertheless extend over the
full extension of the filter body, e.g. essentially over its full
length.
[0020] Preferably, the flow ducts or filter pockets for the fluid
to be cleaned that are open towards the outflow side of the filter
body are at least partially, or completely, isolated from the
purging fluid flow ducts, i.e. the purging fluid stream is passed
through the filter body in such a way that it does not escape (or
as little as possible) on the outflow side of the filter. To this
end, the purging fluid stream is not passed through the filter
pockets open towards the outflow end, or suitable flow-deflecting
means or shut-off means are provided. Preferably, the pressure loss
of the purging fluid between the purging fluid inlet and outlet is
lower when performing regeneration, or when the filter is not laden
with particles, than in the event of outflow through the filter
outlet side.
[0021] To isolate the outflow-side flow ducts from the purging
fluid flow ducts, the side walls of the filter body can be provided
with corresponding recesses at appropriate points. Where
appropriate, a perforated plate or slide valve can also be mounted
on the respective side wall of the filter for this purpose, in
order to provide inlet openings for the purging fluid on the
required ducts and to seal the outflow-side ducts.
[0022] Numerous different embodiments of the filter body according
to the invention are possible, where the filter walls can, for
example, consist of a fabric that can be structured by deformation,
such as a wire mesh or the like, this particularly being in the
form of an endless strip, or also individual filter plates. The
permeable carrier material can be coated with sinterable particles,
such as metal or ceramic particles, where the pore structure of the
filter can be provided by the sintered material. The filter body
can, however, also be a sintered body made of metal, ceramic
materials, including silicon carbide, or other materials.
[0023] If the filter body is constructed from individual layers of
filter walls, which can be achieved both by depositing a strip of
filter material in meandering fashion and by arranging and
connecting separate filter wall segments, particle-tight side walls
can be produced by folding and particle-tight joining of lateral
areas of the strip or the respective filter walls. With this
design, lateral areas of the filter can then be folded over, e.g.
by approx. 180.degree., in order to produce purging fluid inlets
into flow ducts for fluid to be cleaned that are open on the inlet
side, and to at least partially, or completely, seal flow ducts
that are open on the outflow side for the purging fluid.
[0024] The purging fluid inlet and/or purging fluid outlet on the
filter body can be reinforced by stiffening elements. To this end,
side wall areas of the respective filter walls that overlap each
other can be laterally folded over, as a result of which the tabs
formed in this way can be fixed on a housing or the like, where
tabs of this kind can also be provided for fixing other stiffening
elements, such as wires or strips, and can extend over the full
extension of the filter body in the respective direction, e.g. its
height.
[0025] The purging fluid inlet and/or outlet are preferably located
in the region of, or directly at, the outflow-side end of the
filter body or the flow ducts or filter pockets.
[0026] A particle accumulator is preferably provided, which is
connected to the fluid stream outlet of the filter body in
fluid-conducting fashion, so that the particles discharged from the
filter body by the purging fluid stream can be collected in the
particle accumulator. In this context, the particles can be
separated from the purging fluid stream in the particle accumulator
or, where appropriate, also in a separate device located upstream.
The particle accumulator can, for example, display fleece or
felt-like material for separating and retaining the particles. The
filter material of the particle accumulator can be inexpensive,
disposable material, so that the particle accumulator does not
require regeneration. The capacity of the particle accumulator for
separated particles can be several times greater than the capacity
of the filter before the latter requires regeneration, e.g. 2 to 5
times, up to 10 times, or more, this permitting a substantial
increase in the regeneration intervals of the filter system as a
whole.
[0027] It goes without saying that suitable valves or shut-off
devices can be provided on the respective flow ducts of the filter
system, in order to be able to perform regeneration effectively.
For example, the flow inlet and/or outlet of the filter for fluid
to be cleaned can be shut off by corresponding valves when purging
fluid is passed through the filter body to regenerate it. The
purging fluid inlet and/or purging fluid outlet can be provided
with corresponding valves when the filter is in normal operating
state. Further, devices such as slide valves can be provided, for
example, in order to seal the filter body in particle-tight fashion
towards the purging fluid inlet and outlet and prevent uncontrolled
escape of particles from the filter body. Accordingly, valves can
be assigned to the particle accumulator, so that it can be sealed
in particle-tight or fluid-tight fashion when regeneration is
completed, in order to prevent the escape of particles.
[0028] Further, a heating device can be provided for heating the
purging fluid fed to the purging fluid inflow opening. As a result
of this heating, regeneration of the filter can be greatly
accelerated during thermal treatment of the filter residues, such
as incineration thereof. It goes without saying that heating of the
purging fluid can be provided in addition or alternatively to
heating of the filter residues by a heating device designed to heat
the filter walls directly, by means of which spontaneous ignition
of the deposited particles is achieved. The heat supplied to the
filter by the heating of the purging fluid can constitute
.gtoreq.approx. 50%, .gtoreq.approx. 75%, or essentially the entire
quantity of heat required for thermal treatment of the filter
residues.
[0029] Further, a temperature sensor can be provided for measuring
the temperature of the filter walls and/or a fluid flowing through
the filter body, in which context the temperature of cleaned fluid
flowing out of the filter body is preferably measured. The purging
fluid supply and/or the temperature of the purging fluid stream can
be controlled by means of a purging fluid supply device as a
function of this temperature. This makes it possible to prevent
overheating of the filter body during thermal treatment of the
filter residues during regeneration, since the burning-off of the
deposited particles is exothermic, and excessive temperatures can
damage the filter body.
[0030] Further, a device can be provided for controlling the
regeneration of the filter by purging with purging fluid, said
device controlling regeneration as a function of state and/or
operating parameters of the filter and/or of a machine assigned to
the filter that generates the particles to be separated.
Regeneration of the filter can thus be performed on the respective
machine, independently of other devices, such as a regeneration
bench of a workshop. This is of eminent importance for motor
vehicles, in particular, since the time spent in the workshop is
drastically reduced as a result. The control device can, in
particular, be configured in such a way that the purging process
takes place while the machine or the internal-combustion engine
continues to operate. Regeneration can, of course, also be
performed at intervals, where, owing to the risk of overheating of
the filter, regeneration can be performed during part-load
operation, during idling of the internal-combustion engine, or in
any other suitable operating state.
[0031] Preferably, one, several, or all components of the
regeneration device are permanently located on the device or system
generating the particle-laden exhaust gases, such as a motor
vehicle, an internal-combustion engine or an industrial plant,
meaning that regeneration independent of other devices can be
performed, or at least essential components of the regeneration
device are already provided on the device or system generating the
exhaust gases. Components of this kind can include, in particular,
the particle accumulator, the heating device for heating the
purging fluid and/or the regeneration control device, and possibly
also sensors, such as temperature and pressure sensors for
monitoring the pressure of the purging fluid stream or the stream
of exhaust gases to be cleaned. In the case of mobile devices,
these are thus taken along. Further, a pressure-generating device
for generating the necessary purging fluid pressure can be
permanently located on the respective device or system, in which
context the pressure-generating device can display a compressor
and, where appropriate, also a pressure accumulator. In this
context, the compressor can already be provided on the device or
system for other purposes, e.g. it may be a compressor already
present in a motor vehicle. Apart from the pressure-generating
device, all components of the regeneration device can, where
appropriate, already be provided on the device or system, also
including, where appropriate, a pressure accumulator, by means of
which the pressure generated by a compressor can be temporarily
maintained.
[0032] The device or system assigned to the particle filter can, in
particular, be a diesel engine of a motor vehicle, a marine engine
or another internal-combustion engine, a power plant or another
technical plant that generates particles or dust.
[0033] An example of the invention is described and explained below
on the basis of the drawings. The figures show the following:
[0034] FIG. 1 A schematic overall view of a particle filter
according to the invention, with regeneration system,
[0035] FIG. 2 Different views of the filter body with housing
pursuant to FIG. 1,
[0036] FIG. 3 A detail view of the filter body pursuant to FIG. 2
in completely folded state (right) and in partially folded state
(left),
[0037] FIG. 4 Different views of a cylindrical filter body
according to the invention.
[0038] Particle filter 1 with regeneration system according to the
invention comprises a plurality of filter walls 2 for separating
particles, such as soot particles, from the exhaust-gas stream of
an internal-combustion engine, e.g. a diesel engine. In this case,
the filter walls consist of an open carrier material, such as wire
mesh with sintered-on filter material. The filter can, however,
also be a sintered body made of metal, ceramic materials, such as
silicon carbide, or the like. In this context, filter walls 2 form
filter body 3, which is located in housing 4, provided with inlet
nozzle 5 and outlet nozzle 6, thus defining inflow side 7 and
outflow side 8 of the filter.
[0039] In this case, filter walls 2 are produced from profiled,
continuous strip 9 (FIG. 3), which is deposited in meandering
fashion in such a way that many or all of filter walls 2 of the
filter body are formed by the strip. Deflection areas 10 are
located on the inflow side and the outflow side in this context,
this making it possible to obtain a filter body of great tightness.
To increase the stiffness and to influence the flow properties of
the fluid media, the filter walls are provided with profiles in the
form of crests 10a and valleys 10b, which can, however, also be
designed differently, or dispensed with, where appropriate. In this
context, the filter walls are arranged in relation to each other in
such a way that continuous, slit-like filter pockets 11 are formed
between them over the full longitudinal extension and transverse
extension of the filter body, these being alternately open towards
inflow side 7 or outflow side 8. In this context, the filter
pockets extend over the full length and width of the filter body
with a constant slit height. On the inflow side and the outflow
side, the filter walls are further provided with flattened areas 12
in the inflow area and the outflow area, these being formed by
web-like areas 13, projecting and receding in the longitudinal
direction of the filter, these making it possible to alter the
inflow behavior of the fluid into the filter, additionally
stabilize the filter walls and, where appropriate, set the filter
wall spacing. In this context, the direction of flow of the fluid
to be cleaned (arrows, FIG. 2c) corresponds to the longitudinal
direction of the filter strip deposited in meandering fashion,
although it can also differ from it, e.g. be transverse or
perpendicular to it.
[0040] It goes without saying that, if the filter walls are
deposited or profiled appropriately, the slit-like areas can also
extend only over part of the filter length. Further, the profiles
can also display ribs of wave-like shape or running transversely to
the longitudinal axis of the filter, or they can be of a different
design.
[0041] The filter body can be stabilized by additional stiffening
elements, e.g. in the form of externally arranged wires 14,
tab-like notches 15, which can be fixed to fastening areas 16 on
the housing in load-transmitting fashion, elongated stiffening
elements (not shown) extending parallel to the filter walls, or the
like. The stiffening elements can in each case be fastened to the
filter housing by frictional engagement, or also by positive
engagement, or in some other manner. The stiffening elements are,
in particular, located in each case on the inflow and outflow
sides, or also in the inflow and outflow areas of the purging
fluid.
[0042] To facilitate inflow of the fluid to be cleaned (see arrows,
FIG. 2d) into the filter body, and to avoid pressure losses, filter
body 3 is provided with laterally open wall areas 16 in the inflow
area, where these can be directly adjacent to inflow side 7 or,
where appropriate, also at an axial distance. For the purposes of
the invention, however, the direction of flow of the fluid is to be
taken as being the direction of flow of the main volume flow, which
must be seen independently of the inflow and/or outflow area and is
defined by the longitudinal direction of the filter body in this
instance.
[0043] For regeneration of the particle filter according to the
invention, the side areas, which are located between the inflow and
outflow side of the filter, are provided with purging fluid inlet
opening 20 and purging fluid outlet opening 21, which, possibly
with the provision of flow-deflecting means, are arranged in such a
way that the filter pockets are pressurized with purging fluid as
uniformly as possible over the full filter height. To this end, the
purging fluid is supplied to the filter body via feed line 20a and
discharged via discharge line 21a. Further, according to the
practical example, purging fluid feed line 20a and discharge line
21a are located at different heights relative to each other, where
a baffle plate or another kind of flow deflector can further be
located upstream of the purging fluid inlet and also extend over a
relatively large part of the filter height. Moreover, distributors
22, 23 are provided at purging fluid inlet and outlet 20, 21,
distributing the fluid stream over the full height of the filter,
preferably uniformly. The terms "height" and "width" of the filter
refer in this instance to the representation in the Figures. It
goes without saying that the expressions must be changed
accordingly in the event of a different spatial orientation of the
filter.
[0044] Because the purging fluid is passed through the filter
pockets transversely or, more precisely, orthogonally to the
direction of flow of the fluid to be cleaned, particles deposited
in the filter pockets can be removed particularly easily through
the purging fluid outlet, and the filter thus regenerated. In this
context, the purging fluid stream is fed to the individual filter
pockets transversely to the direction of flow of the fluid to be
cleaned. In this context, the purging fluid inlet and outlet are
located at the outflow end of the filter, although it goes without
saying that, where appropriate, they can also be located at
different positions in the longitudinal direction of the filter or
the direction of flow, where, in particular, the purging fluid
inlet can be located upstream of the purging fluid outlet in
relation to the direction of flow. In this context, the purging
fluid stream is fed to each of the individual filter pockets open
on the inflow side, in each case preferably at the level of the
slit-like, laterally open areas of the same, where the slits extend
over the full width of the filter body or the full flow path of the
purging fluid through the filter body. In this context, the slit
height is reduced by preferably no more than 50% of the maximum or
mean slit height along the purging fluid flow path, remaining
essentially constant according to the practical example. The
purging fluid inlet and, independently thereof, also the purging
fluid outlet according to the practical example, are located in the
outflow-side area of the filter, since particles to be separated,
such as soot, are deposited to a greater extent here. Because the
purging fluid stream is in this case located transversely,
especially perpendicularly, to the longitudinal direction of the
filter material strip deposited in meandering fashion, a stable
filter of great tightness can be provided that is easy to
regenerate. Generally speaking, the purging fluid inlet and outlet,
or the purging fluid flow ducts, can be located in the areas of the
filter body where elevated particle deposits are to be
expected.
[0045] Regeneration of the filter is further facilitated by the
fact that, in the area of the flow path of the purging fluid, or of
purging fluid inlet and/or outlet 20, 21, the ducts or filter
pockets, open on the inflow side, for the passage of fluid to be
cleaned display a slit height amounting to .gtoreq.25% (or
.gtoreq.50% or 75%) and, according to the practical example,
approx. 100% of the mean, or also the maximum, height of the flow
ducts for the fluid to be cleaned in the direction of flow. Filter
walls 2 are thus vertically separated from each other in the area
of the purging fluid flow paths or in the area of the outflow-side
connecting areas of the filter walls. According to the practical
example, these areas are provided by web-like areas 13 or the
deflection areas of the strip of filter material deposited in
meandering fashion. It goes without saying that the same also
applies if separate filter walls are connected to each other in
particle-tight fashion by corresponding joints, or if the filter
body is constructed in some other way. However, this avoids acutely
converging filter walls in the area of the outflow-side end of the
filter body, which would result in narrow slits and thus in high
pressure losses in the event of transverse flow of a purging
fluid.
[0046] Very effective purging of the filter is possible because,
although this can also apply to only one of them, where
appropriate, the two purging fluid distributors 22, 23 extend over
an area of the longitudinal axis of the filter, or the direction of
flow of the fluid to be cleaned, that is greater than the width of
the purging fluid inlet or outlet 20, 21.
[0047] Since the purging fluid only has to be fed to the filter
pockets open on the inlet side, in which particles have collected,
the filter pockets open on the outlet side are more or less
completely isolated from the purging fluid ducts in order to enable
effective regeneration of the filter. To isolate the purging fluid
ducts from the filter outlet, edge areas 25 of the filter material
strip are folded over and beaded in order to form particle-tight
side walls of the filter pockets open on the outflow side. It goes
without saying that, where appropriate, only partial lateral
sealing of the respective filter pockets, and thus partial
isolation, may also be sufficient. In order to form fluid-tight
edge or side wall areas, the sintered-on filter material can, for
example, be applied to the carrier in a greater layer thickness.
For example, at the level of the inflow and outflow side of the
purging fluid ducts, the side walls of the filter can also be
designed with corresponding perforated plates having suitable,
particularly slit-like, inlet openings for the purging fluid.
Corresponding, separate flow-deflecting plates can easily be
located laterally on the filter.
[0048] Further, mounted on the filter body in the area of purging
fluid inlet and outlet 20, 21 are stiffening elements, designed in
this case in the form of laterally angled tabs that are integrally
molded on the filter walls or the areas of the filter strip forming
the particle-tight side walls. These tabs are further fixed on
fastening areas 16 on the housing in force-absorbing fashion. This
results in stabilization of the purging fluid inlet and outlet
areas, and particularly also of the filter walls in these
areas.
[0049] The regeneration system further comprises particle
accumulator 30, which can be connected to purging fluid outlet 21
in fluid-conducting fashion in order to accumulate particles washed
out of the filter by the purging fluid. In this context, the
storage capacity of the particle accumulator is several times
greater than that of the filter. The particle accumulator can
display an inexpensive storage medium, such as fleece or felt,
glass or rock wool or the like, in order to retain the particles.
In this context, the storage medium of the particle accumulator is
a disposable material. The particles can be separated from the
fluid in the particle accumulator, or also in a separate, upstream
separating device, where appropriate. When necessary, the particle
accumulator can be connected in fluid-conducting fashion to the
purging fluid outlet, or coupled to the regeneration system, by
means of valves, quick-disconnect coupling 32 or the like. The
particle accumulator can be permanently mounted on the respective
machine, motor vehicle or the like, or, where appropriate, it can
be part of a separate, machine-independent regeneration device,
e.g. of a workshop.
[0050] According to the practical example, the purging fluid stream
is circulated, to which end return line 34 is provided, although
the system can also be of open design, where appropriate, such that
cleaned purging fluid is discharged into the environment.
[0051] The regeneration system further displays a purging fluid
pressurizing device, consisting of compressor 35 and pressure
accumulator 36 in this instance. The compressor and, where
appropriate, also the pressure accumulator can in this case
likewise be permanently mounted on the respective machine or, where
appropriate, part of a machine-independent system. The purging
fluid pressurizing device or the pressure accumulator can be
isolated from the filter or the particle accumulator by means of
valves.
[0052] Further, heating device 37 is provided, so that heated
purging fluid can be fed to the filter for regeneration. As a
result, the deposited particles can be at least partly, or
completely, thermally decomposed or incinerated in the filter in
order to reduce the quantity of waste. It goes without saying that
an additional heating device can be provided that directly heats
the filter walls, an adjacent area of the housing or the like, in
order to assist thermal decomposition or incineration. According to
the practical example, however, more than half, or all, of the heat
necessary for thermal regeneration of the filter is supplied by
purging fluid heating device 37.
[0053] Since the thermal decomposition or incineration of the
particles in the filter is an exothermic process, temperature
sensor 38 is provided, being coupled to heating device 37 via
control device 39 in such a way that the output of heating device
37 can be reduced in the event of spontaneous ignition of the
particles, for example. Further, the valve and the compressor are
operated by control device 39.
[0054] Furthermore, pressure sensors 40 are provided, being located
on the inflow side and the outflow side in this instance, in order
to determine pressure losses across the filter and thereby indicate
the need for regeneration and/or sufficient regeneration of the
filter. The fluid stream required for this purpose can be a
possibly particle-laden exhaust-gas stream of the machine, a
partial purging fluid stream, or any other suitable fluid
stream.
[0055] Further, the regeneration system can display a device for
metering an additive from additive storage tank 45, said additive
being fed into the stream of fluid to be cleaned by means of
conveying device 46 and metering device 47. As a result, the
thermal regeneration of the filter by decomposition or incineration
of the particles can be artificially influenced by the additive.
Accordingly, instead of, or in addition to, an additive supplied
during the regeneration process or in other operating states of the
filter, it is also possible to supply other auxiliaries for
catalytic conversion of fluid components or the like. It goes
without saying that suitable additives can also be fed to the
purging fluid via a corresponding metering device. The individual
components of the additive feed device can likewise be controlled
via control device 39.
[0056] One special advantage of the filter system according to the
invention is that regeneration can, where appropriate, also be
performed while the respective machine continues to operate.
Further, additional valves can be provided on the inlet side and/or
the outlet side of the filter, in order to isolate the fluid flow
ducts and prevent the outflow of purging fluid from the filter.
[0057] The purging fluid can be air, exhaust gases from the
respective device or machine, or any other suitable fluid.
[0058] Regeneration of the filter can, of course, also be performed
at certain intervals, where a need for regeneration can, for
example, be indicated by the control device, e.g. on the basis of a
pressure loss in the direction of flow, determined by pressure
sensors 40.
[0059] FIG. 4 shows a further variant of a particle filter, in
which filter material strip 100 is folded along folding line 101,
running parallel to the longitudinal direction of the strip,
forming a double layer in reference to the folding line that forms
a deflection area located at the face end, i.e. on the inflow side,
or--according to the practical example--on the outflow side.
Sections through the arrangement according to FIG. 4a along lines
A-A, B-B and C-C are shown in FIGS. 4b-d, with an additional
housing in FIG. 4d. The free lateral edges of the filter strip are
each produced with lateral edges of an adjacent double layer,
forming folds 104, also by means of welded connections, where
appropriate, which seal the filter pockets in particle-tight
fashion. In this context, connecting areas 102, 103 of the edge
areas of filter walls of adjacent double layers, following on from
each other on the inflow side or, where appropriate, also on the
outflow side instead, can, as illustrated, be arranged to project
or recede relative to each other. Thus, in keeping with the
terminology of the invention, filter walls 101a and 101b are
assigned to the same double layer, and filter walls 101b and 101c
to different double layers. Located downstream of the folds are
flat contact areas 105 of adjacent filter walls for increasing the
particle-tightness. The direction of flow of the fluid medium
through filter pockets 106, formed by the double layers, is
symbolized by the bent arrows.
[0060] The filter material strip doubled in this way is deposited
in meandering fashion according to FIGS. 4a,b, forming a
cylindrical or semi-cylindrical particle filter segment, in which
deflection areas 107 of greater width are provided radially on the
outside, and narrow deflection areas 108 on a central axis on the
inside. The strip deposited in meandering fashion is thus rolled up
about longitudinal axis 100a of the filter. As illustrated in FIG.
4d, the fluid medium can enter the filter pockets not only through
face end 109, but also from radially outwards via the area of the
filter pocket assigned to deflection area 107, and can escape
through the face-end filter pockets on the outflow side. The
particle filter can thus be designed as a completely cylindrical
filter in one piece. Where appropriate, deflection areas 101 can
also be located on the inflow side. Formed on radially
outward-lying deflection areas 107 are tabs 110, projecting at the
face end, or also radially, by means of which the filter can be
fastened to housing 111 in particle-tight fashion, e.g. clamped in
housing pocket 112.
[0061] In this instance, purging fluid feed line 50 with purging
fluid inlet 51 is provided in the area of axis 100a, to which end
the filter walls display corresponding recesses. Through opposite
purging fluid outlets 53 in the filter pockets, the particle-laden
purging fluid can be passed to a collector 52. In all other
respects, the structure of the regeneration device corresponds to
that in FIG. 1. The explanations relating to the first practical
example apply accordingly.
* * * * *