Note: Descriptions are shown in the official language in which they were submitted.
PROCESS FOR THE PRODUCTION OF A FILTER OR
CATALYTIC CONVERTER BODY
The invention relates to a process for the production of
a filter or catalytic converter body consisting of
multilayer or multi-ply fabrics and/or mesh or lattice
and/or fibrous material, which are sintered together and
subsequently formed into a filter or catalytic converter
body.
Filters and catalytic converters are already known, which
consists of several layers or plies of fabric and mesh
or lattice materials made up of metal fibers or rnetal
wires which have been sintered together. This kind of
sintering is generally carried out in an oven or furnace
under pressure and at a suitably high temperature.
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Filters of this kind are used as so-called deep-bed
filters, whereby the separation of the medium or fluid
to be filtered takes place at or on the surfaces of the
multi-layer or multi-ply fabrics or mesh or lattice or
their components. In the process, the effectiveness or
effectivity of the filter is limited by, among other
things, the size of the surface available.
A catalytic converter or catalyst likewise needs large
surfaces for its effectivity or effectiveness, in or;ier
to allow an exchange of electrons to tale place.
One of the principal fields of ap~:lication of catalytic
converters or catalysts is in conjunction with internal
combustion engi~~es in motor vehicles. With the well-.known
catalytic ~~nverters or catalysts, the intention His to
remove components or substances, such as carbon monoxide,
hydrocarbons and nitrogen oxides, which are harmful to
the environment and to health, from the exhaust gases
produced by engines. For this purpose the catalytic
converters or catalysts are equipped with suitable
substances having a catalytic effect, such as, for
example, platinum, rhodium or vanadium.
Soot filters for diesel engines are also known. These
filters in most cases consist of a ceramic material.
The hot engine exhaust gases or emissions are conducted
through the ceramic filter body. In the porous ducts and
.t the prevailing high temperatures, the soot, i.e.,
carbon, is transformed into gas and ashes in the filter
walls. Instead of ceramic filter bodies, filter bodies
of si ntered materi al have al so al ready been suggested for
this.
The well-known systems have the disadvantage that their
separating surfaces are limited. For this reason
relatively many layers or plies of thick fabric or mesh
or lattice are necessary, with the thicknesses being
able to amount to between a few millimeters and meters,
depending upon the particular application.
The present invention is based on the task of increasing
the separation effect of a filter or catalytic converter
body.
According to the invention, this problem is solved in
that powder-form or granular particles, chips, pieces of
wire or mixtures thereof are sintered onto the individual
layers or plies or their components.
By means of the process according to the invention, a
multiple enlargement of the surface is achieved, through
which a far larger adsorption area and thus a signifi-
cantly larger separating area is made available.
This means that with the same filter capacity the
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thickness of the filter layers or plies can be
significantly reduced.
A further advantage lies in the fact that filter or
catalytic converter bodies, which are manufactured on the
basis of the process according to the invention, exhibit
or display a good flowability at relatively low cost of
manufacture. This is of advantage particularly in an
application with internal combustion engines in motor
vehicles, since losses of capacity are lowered by this
means.
In the state of the art the components generally touch
one another, in general wires, of the individual layers
only, or sintering takes places practically only point-
wise. According to the invention, they are now sintered
with the particles or chips or pieces of wire and also
to one another, resulting in a larger contact area and
hence also a greater strength.
This means that, as the case may be, further measures to
increase the strength of the filter or catalytic conver-
ter body can be dispensed with.
In an advantageous way the individual layers or plies are
sintered together with the sintering-on of the particles,
chips or pieces or wire together in one operation. In
this way the production of the filter or catalytic
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converter body according to the invention can take place
in one sintering operation.
For the introduction of the particles, chips or pieces
of wire and their distribution in the fabrics, meshes
lattices or in the fibrous material, the most varied
measures are possible.
An advantageous and highly effective solution, which is
practicable at low expense and effort, consists in that
the fabric, mesh, lattice or the fibrous material i
covered with a sticky or adhesive fluid, subsequently
provided with the particles, chips or pieces of wire and
finally sintered.
Oil, for example, can be used as the sticky or adhesive
fluid, it being possible to distribute the parts in a
suitable manner by, for example, shaking-in. The sticky
fluid hereby ensures the adherence or adhesion of. the
parts in the fabric, mesh, lattice or the fibrous
material prior to the sintering operation.
As an alternative to this or in combination, provision
can also be made for the fabric, mesh, lattice or the
fibrous material to be electrically and/or magnetically
charged and subsequently provided with particles, chips
or pieces of wire.
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It goes without saying that the reverse of this measure
is also possible within the scope or framework of the
invention, i.e., that the particles, chips or pieces of
wire are charged.
The prerequisite for this, of course, is that the parts
used are appropriately electrically capable of conduct-
ivity or of being magnetized or are magnetic.
Another possibility of introducing the particles or
similar parts onto the fabric, mesh, lattice or the
fibrous material consists in screen printing onto the
individual layers or plies. Through screen printing or
a similar process, exact delimitations of the parts
coated with the particles from the other areas can be
attained. In this way locally targeted 'effects can be
achieved.
The fabric, mesh, lattice or the fibrous material can
consist of the most varied materials, such as, for
example, metal, synthetic material or plastic or of
ceramic substances. Likewise, combinations of these are
also conceivable.
The same applies to the particles, chips or pieces of
wire, which may consist both of metal, plastic or of
ceramic materials or of mixtures thereof.
Their use depends on the particular application.
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In an application as a catalytic converter body,
materials are used or added, which possess catalytic
properties, such as, for example, platinum, rhodium or
vanadium.
A typical example or embodiment of the invention is
described below in principle with the aid of the drawing.
A fabric or mesh or lattice consists of a plurality of
layers or plies 1 of in each case interwoven, interlaced
or meshed components, in general metal wires 2.
Such a fabric or mesh or lattice is covered or saturated
or soaked or impregnated with a sticky or adhesive fluid,
after which particles 3 are introduced into the interior
by shaking-in and distributed there appropriately by the
shaking operation. In this process the sticky or adhesive
fluid undertakes the task of creating adhesion or fixing
of position. Following this, a sintering operation is
carried out, which usually is performed depending on the
materials involved and is widely known, which is why this
will not be described here in greater detail.
By rneanu of the sintering operation both the individual
layers or plies t with their wires 2 and the particles
3 are sintered to one another and in this way form a
unit. In practice it was found that by means of a
catalytic converter, which is provided appropriately with
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materials having a catalytic effect or is coated
therewith, a catalytic effect occurs already at
relatively low temperatures in comparison with the state
of the art. This means that a suitably high effect is
ach i eved i n as soon as the eng i ne i s i n the start i ng
range. Furthermore, it was found that virtually 90~ of
the highly noxious substances can be separated with the
catalytic converter body according to the invention. This
applies, for example, to polycyclic hydrocarbons.
Through a mixture of metal parts and ceramic materials,
a high heat resistance can be achieved, attention having
solely to be given to obtaining an extensively uniform
coefficient of thermal expansion.
Through an appropriate control of the provision and
introduction of the particles, chips or pieces of wire
or mixtures thereof, filter or catalytic converter bodies
can also be manufactured with different porosities and
thus different flow resistances. It is likewise possible,
if required, to design sections or areas of the filter
or catalyitic converter body completely fluid or gas-
tight.
