U.S. patent application number 11/993046 was filed with the patent office on 2010-11-04 for method of producing exhaust-gas carrying devices, in particular exhaust-gas cleaning devices.
Invention is credited to Peter Kroner, Stefan Merschkoetter, Stefan Schmidt.
Application Number | 20100275443 11/993046 |
Document ID | / |
Family ID | 36343933 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100275443 |
Kind Code |
A1 |
Kroner; Peter ; et
al. |
November 4, 2010 |
METHOD OF PRODUCING EXHAUST-GAS CARRYING DEVICES, IN PARTICULAR
EXHAUST-GAS CLEANING DEVICES
Abstract
A method of producing exhaust-gas carrying devices, in
particular exhaust-gas cleaning devices, makes provision that the
outer geometry of each substrate is ascertained. An outer housing
with an adapted geometry is manufactured dependent on this outer
geometry. The substrate, together with a compensation element, are
accommodated and clamped in this outer housing.
Inventors: |
Kroner; Peter;
(Zweibruecken, DE) ; Schmidt; Stefan; (Langweid am
Lech, DE) ; Merschkoetter; Stefan; (Augsburg,
DE) |
Correspondence
Address: |
PAMELA A. KACHUR
577 W Santee Drive
Greensburg
IN
47240
US
|
Family ID: |
36343933 |
Appl. No.: |
11/993046 |
Filed: |
March 14, 2006 |
PCT Filed: |
March 14, 2006 |
PCT NO: |
PCT/EP06/02332 |
371 Date: |
July 13, 2010 |
Current U.S.
Class: |
29/890 |
Current CPC
Class: |
Y02T 10/12 20130101;
F01N 2350/04 20130101; F01N 13/18 20130101; F01N 3/2842 20130101;
F01N 3/0211 20130101; F01N 3/2828 20130101; F01N 3/2853 20130101;
Y02T 10/20 20130101; Y10T 29/49345 20150115; F01N 2450/02
20130101 |
Class at
Publication: |
29/890 |
International
Class: |
B21D 51/16 20060101
B21D051/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2005 |
DE |
10 2005 029 163.5 |
Claims
1. A method of producing an exhaust-gas carrying devices, in
particular an exhaust-gas cleaning device, which has an outer
housing with an insert piece clamped therein, the insert piece
comprising a substrate, which has exhaust-gas flowing through the
substrate, and an elastic compensation element that surrounds the
substrate including the following steps: a) determining an
individual outer geometry of the substrate; b) ascertaining a
geometry of the outer housing that is adapted to the individual
outer geometry of the substrate to achieve a required clamping
force individually adapted to, and to be exerted on, the insert
piece; c) producing the outer housing with adapted geometry; and d)
mounting and clamping the insert piece in the outer housing, with a
closure of the outer housing being effected in at least one of a
pressure-controlled and force-controlled manner.
2. The method according to claim 1, wherein, in addition to the
determination of the individual outer geometry of the substrate,
including the step of determining an individual weight of the
elastic compensation element.
3. The method according to claim 1, including producing the adapted
geometry of the outer housing by incremental deformation.
4. The method according to claim 1, wherein the outer housing is
closed in order to clamp the insert piece.
5. The method according to claim 4, wherein suitable parameters for
a closure process are ascertained prior to closing the outer
housing.
6. The method according to claim 4, including closing the outer
housing in at least one of a pressure-controlled and
force-controlled manner.
7. The method according to any of the claim 4, including closing
the outer housing is effected in at least one of a
distance-controlled and geometry-controlled manner.
8. The method according to claim 1, wherein the substrate is
essentially cylindrical and has a base area that deviates from a
circular shape.
9. The method according to claim 1, including measuring the
substrate to determine the individual outer geometry.
10. The method according to claim 1, including feeding data
ascertained for the insert piece into a control unit such that the
control unit can establish an individual geometry of an associated
outer housing.
11. The method according to claim 1, wherein the exhaust-gas
carrying device is at least one of an exhaust-gas catalytic
converter and a diesel particle filter.
12. The method according to claim 1, including using a sheet metal
housing for the outer housing.
13. The method according to claim 1, including producing the outer
housing by wrapping the outer housing around the insert piece.
14. The method according to claim, including pressing the outer
housing against the insert piece in a calibration process.
15. The method according to claim 1, wherein the outer housing is
comprised of several shells that are pressed against the insert
piece and fastened to each other.
16. The method according to claim 1, including tamping the insert
piece into a prefabricated cylindrical outer housing which has an
adapted geometry.
Description
TECHNICAL FIELD
[0001] The invention relates to a method of producing exhaust-gas
carrying devices, in particular exhaust-gas cleaning devices, all
of which have an outer housing with an insert piece clamped
therein, the insert piece comprising a substrate which has
exhaust-gas flowing through it, and an elastic compensation element
which surrounds the substrate.
BACKGROUND OF THE INVENTION
[0002] Exhaust-gas carrying devices representing the subject-matter
of the invention are, in particular, exhaust-gas cleaning devices
such as catalytic converters and diesel particle filters or a
combination thereof. Such devices contain insert pieces that are
very sensitive to radial pressure. Traditionally, these insert
pieces are predominantly ceramic substrates that have a gas flowing
axially through them, and which are wrapped in an elastic
compensation element (usually referred to as a lining mat). These
insert pieces are retained in an outer housing in axial and lateral
directions mainly by radial clamping, while an additional axial
support is possible, for instance by a wire mesh ring. The clamping
effect has to be large enough so that there is no displacement of
the insert piece relative to the outer housing in an axial
direction during a driving operation owing to the gas pressure as
well as through vibrations. On the other hand, the radial pressure
(or in more general terms, the pressure acting laterally inwards)
must not be so large as to destroy the insert piece, in particular
to destroy the catalytic converter substrate or the diesel particle
filter substrate both of which are sensitive to pressure.
[0003] The insertion and clamping of the insert piece in the outer
housing is usually effected by a so-called wrapping process. Here,
a sheet metal envelope is preformed by bending the sheet metal
around a roller or mandrel. Subsequently, the insert piece, which
includes the substrate and lining mat, is pushed laterally into a
prefabricated sheet metal envelope; the latter is firmly wrapped
around the insert piece in a force-controlled manner, and finally
the envelope is closed by welding. In doing so, the lining mat is
compressed.
[0004] As the dimensions of the substrate (as well as those of the
lining mat) are subject to certain manufacturing tolerances, an
optimum clamping of the insert piece in the outer housing is not
always ensured by this known method. While a substrate with a
particularly small diameter possibly may not be clamped to a
sufficient extent, it may happen that a particularly large
substrate will be destroyed due to the higher pressure exerted by
the compressed lining mat.
[0005] In addition, the lining mat, which is provided between the
substrate and the outer housing and is intended to provide for
pressure compensation and a consistent pretension, is subject to a
certain setting process after compression (relaxation), whereby the
pressure which is imparted by the lining mat to the substrate
diminishes. The spring-back effect of the outer housing after
having been inserted and clamped also has the effect that the
pressure initially applied on the substrate, and with it the
applied clamping force, decreases. Furthermore, the retaining
pressure of the lining mat reduces in operation (e.g. by
aging).
[0006] One theoretical possibility to compensate for the
dimensional tolerances of the insert piece during the clamping
operation is to close the outer housing in the method described so
far in a pressure-controlled or force-controlled manner. In
practice, however, it is difficult, even using this measure, to
compensate for the large variations in the retaining pressure of
the lining mat.
[0007] It is the object of the invention to present a method that
provides for a sufficiently safe clamping of the insert piece in
the outer housing with minimal reject rates.
SUMMARY OF THE INVENTION
[0008] This objective is achieved by a method that includes the
following steps: a) determining an individual outer geometry of a
substrate, b) ascertaining a geometry of an outer housing that is
adapted to the individual outer geometry of the substrate, c)
producing the outer housing with adapted geometry, and d) mounting
and clamping an insert piece in the outer housing.
[0009] With the methods known so far, a uniform outer housing has
always been used. This uniform outer housing was bent to have a
round shape and was closed around the insert piece in a
force-controlled or pressure-controlled manner. In the course of
the pressure-controlled closure, tolerances in the size of the
insert piece were partially counterbalanced in that the outer
housing was closed to a somewhat further extent. The invention
takes another path by first ascertaining the outer geometry of each
individual substrate prior to installation, and subsequently
forming, depending on this outer geometry, an outer housing that is
exactly adapted to the outer geometry of the respective substrate
(including the space for the lining mat). The insert piece, that
includes the substrate and compensation element, is then mounted
and clamped in its individually fabricated outer housing. In this
way, an area-related density of the compressed mat, and with this
the retaining pressure exerted by it, is subject to markedly lower
fluctuations as is the case in prior art. This means that each
insert piece is clamped with a retaining force that is necessary
for that insert piece. Thus, it is possible with the method
according to the invention to reduce the load on the substrate,
which achieves a better durability. "Adapted geometry of the outer
housing" means in this context that the shape and the dimensions of
the outer housing are specifically tailored. According to the
invention, provision is made that the geometry of the outer housing
is determined directly from the outer geometry of the substrate.
Intermediate steps such as a weight determination or weight
calculation are not provided for this purpose.
[0010] For improving the accuracy while ascertaining the geometry
of the outer housing, the individual weight of the compensation
element is determined in addition to determining the outer geometry
of the substrate. This is expedient because the pressure, which is
to be exerted by the compensation element, depends inter alia on a
mass of the insert piece and with this also on a mass of the
compensation element.
[0011] In order to be able to model even the smallest structures of
the substrate, the adapted geometry of the outer housing is
produced by incremental deformation. This is particularly
advantageous with out-of-round or polygonal substrate
cross-sections.
[0012] As already mentioned, it is possible to close the outer
housing in order to clamp the insert piece. In this case it will be
of advantage to ascertain suitable parameters for the closure
process prior to closing the housing. The load on the substrate can
thereby be kept particularly low.
[0013] The process of closing the housing can be effected in a
pressure-controlled or distance-controlled manner. A combination of
both methods is also possible. A distance-controlled closing method
is particularly advantageous, as the geometry of the substrate, and
with this the "target geometry" of the outer housing, is already
known.
[0014] As the outer housing can be adapted to almost any shape of
the substrate due to the individual forming process, the method
according to the invention can be applied with particular advantage
to a substrate that is essentially cylindrical and has a base area
that deviates from a circular shape. Thus, in particular,
out-of-round contours, for example oval or so-called tri-oval
(tri-oval referring to an essentially triangular shape with rounded
corners) cross-sections, come into consideration. The method
according to the invention allows a defined inhomogeneous or
targeted surface pressure that results, especially with such
out-of-round contours, in a lower amount of rejection and a better
durability. In this way it is possible for a substrate with an oval
cross-section to achieve a retaining pressure that is higher in the
areas with a larger radius as would be the case with a
prefabricated round or preliminarily rounded outer housing which is
merely wrapped around an oval substrate. At the same time, local
pressure peaks are avoided in the areas with a smaller radius,
which occur in the conventional method due to the spring-back
effect. In this way a smaller load on the substrate is
achieved.
[0015] A particularly simple possibility of determining the
individual outer geometry is to measure the substrate.
[0016] According to one embodiment, data ascertained for the insert
piece is fed into a control unit, and in the control unit the
individual geometry of the associated outer housing is established.
All data is fed into the control unit in a fully automated way by
coupling with the measuring devices. The control unit then
ascertains the tailored geometry. At the same time the control unit
can be coupled with the tool(s) shaping the outer housing so as to
have the desired geometry.
[0017] The device that is produced by the method according to the
invention is, according to one example embodiment, an exhaust-gas
catalytic converter, a diesel particle filter or a combination
thereof. A pressure-sensitive substrate is provided in each case as
a core of the insert piece.
[0018] In particular, the housing is configured as a sheet metal
housing.
[0019] Apart from the already mentioned wrapping process, the
method according to the invention can be applied to all methods of
producing exhaust-carrying devices and to all methods that rely on
a sheet metal housing. Apart from wrapping, in which a
prefabricated sheet metal section is wrapped around the insert
piece and subsequently fastened and closed at its edges when the
predetermined inner dimensions are reached, a so-called
"calibration" is possible, too. Here, pressure is exerted from
outside against the circumference of a prefabricated closed tube in
order to plastically deform the tube and press the tube against the
insert piece.
[0020] A third method makes provision for a housing that is made up
of several shells that are pressed against the insert piece and
subsequently fastened to each other.
[0021] A fourth embodiment provides for a so-called "tamping"
method. Here, a closed cylindrical housing is produced whose inner
geometry is already adapted to the outer geometry of the insert
piece. After this, the insert piece is inserted into the housing
from a front side.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a longitudinal sectional view through a device in
the form of an exhaust-gas cleaning device, which is produced by
the invention;
[0023] FIG. 2 shows schematic views of measuring devices and tools
that are used in the method according to the invention;
[0024] FIG. 3 is a frontal view of a device produced by the method
according to the invention, with a wrapped outer housing;
[0025] FIG. 4 is a perspective view, partially in section, of a
calibration tool which is used in the method according to the
invention;
[0026] FIG. 5 is a frontal view of a device produced by the method
according to the invention, with an outer housing made up of
shells; and
[0027] FIG. 6 is a principle sketch showing the process of tamping
which is used in the method according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] FIG. 1 illustrates an exhaust-gas carrying device in the
form of a vehicular exhaust-gas cleaning device, and which is
accommodated in a motor vehicle. The vehicular exhaust-gas cleaning
device is either an exhaust-gas catalytic converter, or a diesel
particle filter, or a combination of both.
[0029] A core piece of the exhaust-gas cleaning device is an
elongated, cylindrical substrate 10, which comprises, for example,
of a ceramic substrate or a type of wrapped, corrugated board or
other catalytic carrier or filter material with or without a
coating. The substrate 10 may have a circularly cylindrical
cross-section or a cross-section that is out of round. For the sake
of a simplified illustration, a circularly cylindrical
cross-section is shown in the Figures. The substrate 10 is
surrounded by a lining mat 12, which acts as an elastic
compensation element between the substrate 10 and an outer housing
14. The outer housing 14 is designed to have a very small wall
thickness; in particular the outer housing 14 is made from sheet
metal. At the upstream and downstream positions, an inlet funnel 16
and an outlet funnel 18, respectively, are connected with the outer
housing 14.
[0030] The substrate 10 forms a prefabricated unit with the lining
mat 12.
[0031] In operation, exhaust gas flows through the inlet funnel 16
at the end face into the substrate 10 and finally leaves, with a
smaller amount of harmful substances, the substrate 10 at the
opposite end face in order to leave the cleaning device through the
outlet funnel 18.
[0032] The manufacturing of the cleaning device will be explained
in the following by means of FIGS. 2 and 3. FIG. 2 shows various
measuring stations with which properties of each of the insert
pieces (i.e. of the substrate 10 and lining mat 12) to be installed
are ascertained in view of an individually adapted outer housing
for achieving an optimized clamping force of the insert piece in
the housing 14.
[0033] The measuring stations are coupled via a control unit 20
with tools for producing the outer housing 14 and for mounting and
clamping the insert piece in the outer housing 14. The stations,
which are explained in detail below, are described in one example
order of a production method.
[0034] In a first measuring device the outer geometry (form and
outer dimensions, in particular circumference) of the substrate 10
is ascertained by using contact-free measuring sensors 22. The
measuring sensors 22 are connected with the control unit 20, which
stores the measured values obtained for the substrate 10.
[0035] Subsequently, the weight of the lining mat 12 is determined
on a scale or balance 24, which likewise is coupled with the
control unit 20. Here too, the data obtained is stored in the
control unit 20.
[0036] With the established data of the insert piece (the substrate
10 and lining mat 12) to be installed, the control unit 20
ascertains a geometry of the outer housing (with consideration of a
setting factor and compliancy of the fitting mat 12) which is
adapted to at least the individual outer geometry of the substrate
10. This can be performed by calculating or by comparison with an
association matrix stored in the control unit 20. The individual
geometry is targeted to achieve the required clamping force which
is to be exerted and is individually adapted to the insert
piece.
[0037] Apart from the data which has already been mentioned, it
would be possible to consider further data of the individual insert
piece during the calculation of the outer geometry of the housing,
such as the weight of the substrate 10, for example.
[0038] In a next step, this ascertained outer housing 14 with
adapted geometry is produced by incremental deformation (as
indicated at 26). This may be done, for example, by bending around
a mandrel or roller. In this process, however, the bending roller
must have very small dimensions so that the necessary small
deformations can be produced.
[0039] Finally, the insert piece prefabricated from substrate 10
and lining mat 12 is assembled together with its tailored outer
housing 14 in the so-called "wrapping method" (as indicated at 28).
To this purpose, the prefabricated outer housing 14 is slightly
opened and the insert piece is laterally inserted into the outer
housing 14. The outer housing 14 is closed in a pressure-controlled
and/or distance-controlled manner by overlapping edges 30, 32 being
superimposed to such an extent that the dimensions of the resulting
outer housing 14 are equal to the values as ascertained earlier.
The closure process is performed with the aid of suitable
parameters (pressure, distance) which earlier were ascertained in
the control unit 20 and adapted to the individual substrate 10 or
outer housing 14. As a next step, the overlapping edges 30, 32 are
welded to each other, or crimped or soldered. The finished product
is illustrated in FIG. 3.
[0040] Apart from wrapping the outer housing 14, the assembly may
also be performed by a so-called calibration. A corresponding
calibration device is shown in FIG. 4. This device has numerous
radially movable jaws 34 which have the shape of a circle segment
and are able to move towards each other so as to define a ring. The
circularly cylindrical, tubular outer housing 14 (in which the
insert piece is axially inserted) is inserted into the interior of
the work space, which is circumscribed by the jaws 34.
Subsequently, the jaws 34 are moved radially inwards, while the
values with respect to the geometry of the outer housing 14 are
used, which were earlier ascertained in the control unit 20. This
means that the desired dimensions of the outer housing 14, which
before were ascertained by the control unit 20, are achieved by a
distance-controlled movement of the jaws 34 with simultaneous
plastic deformation of the outer housing 14, which beforehand was
circumferentially closed and prefabricated with a correspondingly
larger diameter.
[0041] Instead of the jaws 34 shown in FIG. 4, it is also possible
to perform the calibration with rollers that are laterally pressed
against the outer housing 14 (with the insert piece inserted
therein) by the predetermined travel distance and then are rotated.
In this context, a so-called "spinning process" is also possible,
in which the outer housing 14 (with the insert piece arranged
therein) is moved by the predetermined travel distance against a
single roller. Subsequently, a relative rotation occurs between the
roller and the outer housing 14 complete with the insert piece, so
that the roller circumferentially presses into the outer housing 14
and plastically deforms the outer housing 14 in an inward
direction.
[0042] The embodiment shown in FIG. 5 uses two or more shells 36,
38 which are inserted into each other. In this case too, the shells
36, 38 are inserted into each other in a distance-controlled,
pressure-controlled, or force-controlled manner so far until the
inner dimensions are equal to the ascertained dimensions. The
shells 36, 38 are then welded to each other, crimped or soldered,
for instance. It is possible, of course, to form the shells 36, 38
preliminarily in such a manner that they have the desired final
dimensions, similar to the case described in connection with FIG.
6.
[0043] FIG. 6 symbolizes the so-called "tamping" process. In the
measuring device the desired dimensions of the outer housing 14 are
ascertained. Subsequently, a cylindrical, tubular outer housing 14
is produced with the desired target diameter and the corresponding
shaping. This is performed by rolling, for instance. Then the
insert piece is axially forced into the selected outer housing 14.
Here, corresponding funnel-shaped implements are provided for, of
course. As an alternative to producing outer housings with the
desired dimensions it is also possible to select from prefabricated
outer housings, having different diameters, exactly that one which
is suited in terms of the dimensions.
[0044] It is to be emphasized that the illustrated method is not
intended for experimental purposes in which a single catalytic
converter or diesel particle filter is produced. Rather, the method
is intended for series production in which each substrate, together
with its lining mat, receives its tailored outer housing. The
described method results in a better quality of the produced
devices with a low investment of capital for the devices.
* * * * *