Note: Descriptions are shown in the official language in which they were submitted.
7~;7
The present invention relates to apparatus for the
catalytic purification of the exhaust gases in internal com-
bustion engine~ wherein a cylindrical catalyst body traversed
by the gas in the axial direction, is arranged in the interior
of a sheet metal housing and is shock-dampened by means of a
resiLient envelope provided at its circumference which also
seals the body relative to an outer housing.
When using delicate ceramic envelope materials~ for
example, on aluminum silicate base, premature wear thereof
will occur without special sealing of the envelope at its end
face Such wear is caused on the one hand by the exhaust gas
pulsations and on the other hand by the corrosive attack of
the exhaust gases on the free front surface o the envelope
To avoid this disadvantage, it has been proposed
in German Patent Publication P 25 15 732, corresponding to
Canadian Patent-1064399, dated 10/10/79, to deflect the e~-
hause gases into the interior of the catalyst body by sheet
metal rings fastened to the housing. Such a measure gives
I
no protection against chemical corrosion.
The problem underlying the invention is to seal
~: the space between the catalyst body and the housing in a
¦ manner which not only ensures the complete closure thereof
l ~ but also serves to retain the catalyst body.
~: .
~ .(;~ ,
~.
-- 1 --
... ... . . ~, . .. . . . .. . .
.7~7
According to the invention, this problem is solved
by working, smoothing and/or sizing the catalyst body at its
circumferential zone contiguous to at least one of its frontal
edges and fitting thereon an elastic seal ring which extends
beyond the frontal edge. The seal ring is radially extended
to be forcibly applied at its free end against the inside of
the outer housing wall about the entire circumference of the
housing. Such a seal ring contributes both to the radial and
to the axial retention of the catalyst body and achieves an
elastic support of the catalyst body in the area o its oppo-
site front edges.
At the same time the seal provides a hermetic
closure of the space containing the shock-absorbing envelope
between the catalyst body and the housing surrounding the
latter. A precise sizing or working, i.e., smoothing, o the
circumference of the catalyst body is necessary only in a
limited area contiguous to the end faces. For the purpose of
sizing, a layer of a cement type material, for example a mater-
ial available on the market under the designation of BLAKITE,
a TM of the Johns Manville Co., is applied. This layer causes
an increased compression of the envelope in radial direction,
whereby in particular the axial hold of the catalyst body is
~ improved.
- The assembly of the apparatus is facilitated by
the ~act that the housing may be divided into two hal shells.
The catalyst body, provided with the seal rings and wrapped
-~.
`' - 2 -
,
.
- with a shock attenuating elastic envelope, is placed into
the lower half shell; then the upper half shell is pressed
on, while clamping the free end sections of the seal rings
relative to thè inner wall of the housing~ Thereafter, the
two sections of the housing are together. After the union
of the two half shells, the free end sections of the seal
rings can be fixed relative to the shells by spot welding.
To achieve an improved spring action of the seal
rings, the housing may have an annular axial enlargement in
the contact area with the free end section of the seal ring,
while the ring itself may be both radially and axially en-
larged to firmly seat against the housing wall over an en-
larged area. Thereby the free end section of the seal ring
. presses against the inner wall of the hou~ing independently
of the clamping of the resilient envelope to the housing.
. At the same -time the enlargement serves to provide a certain
axial fixa~ion of the catalyst body~ as the free end section
of the seal ring engages securely in locking form against
; the housing.
. An improvement of the exhaust gas.conduction can
be further achieved by reducing the diameter of the seal
ring radiall~ inward, in its middle sectîon This concen-
trates the exhaust gases closer to the axis of the catalyst
since the smallest diameter of the rîng is smaller than the
outside diameter of the catalyst body. With this form of
exhaust gas conduction, an optimaL utilization of the effec-
tive surface of the catalyst body during flow through it is
: obtained
. ~
- 3 -
~ ~ 2~
An example of construction of the device according
to the invention is e~plained in the following description
with reference to the accompanying drawing~ in which:
FIG 1 is an axial section through the catalyst
device;
FIG 2 is a transverse section along II-II o~
FIG l; and
FIG 3 is an enlarged view of a segment of a
sea-l-ring shown in FIG 1, iliustrating its construction in
cross-section.
The catalyst body 1 is a monolithic, subs~antlally
cylindrical or uniform cross-sectional axiall~ traversible
block, carrying about its circumference, a resilient envelope
2 made of an aluminum silicate based material, for example a
material commercially available under the designation and
trademark Cera Blanket or Saffil. The Cera Blanket is a mat
o firepro~f ceramic fibres of about 60% aluminum oxide and
Na2), 39% silicon dioxide and a small remainder of FeO3,TiO2.
SafiL is a mat of fireproof ceramic fibres of about 95%
aluminum oxide and 5% silicon dioxide, with some trace elements.***
The envelope 2 clamps the eatalyst body 1 in radial direction
relative to the sheet metal housing 3, which surrounds it.
The sheet metal housing has inwardly tapering ends, which has
***Foo~no~e: The manufacturer of Saffil is ICI-Imperial
ChemicaL Industries, Ltd., Runcorn, Cheshire, England,
and o Blakite and Cer~ablanket is Johns-ManvilLe
International Gorp., New York, U.S.A.
.~ .. . .
... ~,, . , . .. , , ~ .. , . .. . ,~, .. .. . .. .. ..... ......... . . . . . . .....
-
~ ~ Z7 ~ 7
a form corresponding to the catalyst body 1 and is provided
in known measure with means of connection to the exhause of
an engine. In the present instance the form of the catalyst
body and housing is approximately elliptical in cross-section
as seen in FIG 2. Pre~erably, the housing is slightly sm~ller
in its diameters so as to apply a tight closing pressure on
the envelope 2 and catalyst body 1. The catalyst body 1 is
formed~ in its circumferential end zones 4 (contiguous to the
frontal edges) with recessed surfaces on which is fit a ringO
5. The catalyst body is sized at the zones 4, by appli-
cation of a cement type mass, e.g. of a material commercially
available under the aforementioned TM BLAKITE. BLAKITE is
a mortar comprising fireproof clay and cyanite mixed with
water glass; water glass being another expression for sodium-
tetrasilicate. The term sized as used herein means to
treat the catalyst body on its circumferential zones 4 as by
coating the same with the mortar or other material until a
certain outer diameter is reached within small tolerances
for the set up and close fit of the rings 5. The rings 5,
are resilient seal rings formed of suitable metal which are
seated onto these recessed surfaces so as to be axially fLx-
ed at their outer end and to have their free outer end sec-
tions 6 radially extended in an arched portion 7 which engages
the housing 3. The end sections 6 may be connected with the
housing by spot welding in the region of the arched portions
7 forming an annular enlargement of the rings 5, beyond the
- - 5 ~
~ Z7~7
diameter of the catalyst body. The resilient envelope mater-
ial is at least partially pulled over the seal rings S in the
end region of the catalyst body 1,
As can be seen in FIG 2, the outer metallic housing
3 is divided into two half shells 3a and 3b, which are con-
nected together by spot welding at their laterally circling
flanges 8,
FIG 3 shows a segment of a seal ring 5 which is
provided with a radiaLly inward cross-section annular reduction
of foLd 9, which has an inner diameter smaller than the out-
side diameter of the catalyst bodyO The latter fold causes
a def.lection of the exhaust gas stream from its axial path
radially, hence concentrating the gas stream. The fold also
enables the ring to be radially and axially movable.
It wilL be seen from the foregoing that the various
objects and advantages of the present invention, enumerated
earlier, are all obtained in simple economical fashion. Var-
ious modifications and changes have been suggested in the
foregoing description. Others will be obvious to those
.
skilled.in this art, Consequently, it is intended that the
present disclosure be illustrative only and not limiting of
the sclope of the invention.
.
. ' ;,
:
- 6 -
