DE3043995A1 - EXHAUST GAS FLOWED PARTICULATE FILTER FOR DIESEL MACHINES - Google Patents

Description

3U43995

A abgasdurchströ'mter Sehwebeteilchenfilter for Dieselmasehinen "is, for example, by the US-PS 4 054 AM _β-known

The filter area available there is only small in relation to the volume, as individual filter elements after taking up the suspended particles in one next to it horizontal reaction chamber are moved.

The invention is based on the object of providing a considerably larger filter area for a given volume which can be cleaned by burning out after saturation.

This object is achieved by the features set out in the characterizing part of claim 1.

Further advantageous embodiments of the invention; result from the subclaims "

The inventive training is that Depositing a substantial rope of the carbonaceous Guaranteed suspended particles from the exhaust gases, with a relatively long operating time achieved until saturation will. The filters are suitable by heating the separated suspended particles to the firing temperature to eliminate these again by incineration.

Embodiments of the invention are shown in the drawings. Show in the drawings

1 shows a partial view of a motor vehicle chassis with a diesel engine and

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neter exhaust system with suspended particle filter in perspective view,

Fig. 2 is a partial perspective view of a Suspended particle filter of the system

Fig »1,

Pig. 3 is a perspective view of a rope

other design of a motor vehicle chassis with diesel engine and associated exhaust system,

4 is a perspective view of the swivel participation filter of the system according to Figo3 »

Fig «5 a to k, m, η and ρ different configurations of the channels in a suspended particle filter according to FIG. 2.

A motor vehicle chassis 10 comprises according to FIG _e 1 on a frame 11 which carries a diesel engine 12 having two rows of cylinders arranged in the Y. An exhaust gas collection box 14 is assigned to each cylinder row. The outlets of the suspended particle filters are connected via a Y pipe / to a sound absorber 19, from which the exhaust gases flow out into the open via an exhaust pipe 20 _e

Each suspended particle filter 16 contains a G-ehäu-

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This suitable shape, which is attached to the frame 11 ″ ₀ Inside the housing is arranged an ceramic filter element which can have any suitable shape. According to FIG is enclosed and in its interior contains a plurality of porous partition walls 24. By these two groups of mutually parallel channels are formed, which extend from the

28 /
one side / of the monolith 22 to the other side 30 thereof. One group forms inlet channels 26 which are open on side 28 and closed on side 30, while the other group represents outlet channels 27 which are closed on side 28 and open on side 30.

With the ^ auform naeh Pig2 the channels have 26 and 27 square cross-sections, although other cross-sectional shapes are possible as will be described will. The inlet and outlet channels are arranged in vertical and horizontal rows, with the inlet channels closed the outlet channels are staggered like a chessboard. Each intermediate wall 24 therefore lies between an inlet channel and an exhaust port. It thus becomes a large pile area created.

The partition walls 24 of the monolith 22 have such a porosity that the exhaust gases pass through them from the inlet channels 26 can flow into the outlet channels 27, and the pores are dimensioned so that a substantial part of the in

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suspended particles contained in the exhaust gases from the partition walls 24 to be withheld. A sufficiently effective filtering has been experimentally established, if a medium one Porosity of $ 10, a mean pore size between 2 and 15 microns and a single pore size between o.5 to 70 microns were chosen »This was achieved when the square channels 26 and 27 had a cross section with a side length of about 1.524 mm and the partition walls 24 had a thickness of about 0.381 mm. Since practically the entire Surfaces of the channels are effective as filter surfaces,

2 3 there is a filter area of more than 78.6 mm per cm Monolith volume. With a very low flow resistance, a very large filter surface is created with little space requirement. An increase in the porosity over the value $ 10 would further reduce drag can be expected, at least until the cross-sections of the inlet and outlet channels allow the gas flow limiting. Factors become,

During operation, the exhaust gases coming from the diesel engine 12 enter the suspended particle filter 16 through the open ends of the inlet ducts 26 and are distributed over the entire area in order to get through the pores of the partition walls 24 into the adjacent outlet ducts 27.

A large part of that contained in the exhaust gases Suspended particles settle on the inner surfaces of the inlet

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channels 26 and "forms a layer there, the Ms to one the flow of the exhaust gases can increase in thickness »The cleaned exhaust gases pass through the open ends of the Exhaust ducts in the adjoining part of the exhaust system.

After a certain operating time, the deposited suspended particles reach the layer in the inlet channels the thickness that interferes with the flow of exhaust gases. It is then the cleaning of the filter or its replacement required against a new filter. Cleaning the Filter is most beneficial by heating the monolith to a temperature at which the accumulated suspended particles react by reacting with oxygen from the exhaust gases are ignited and burned. The material of the monolith easily maintains these temperatures the end. The cleaning in this way can be done while the diesel engine is in operation, although of course a suitable one Monitoring of the firing temperatures must be provided. Cleaning can also be done by removing the monolith which is then brought to the ignition temperature of the collected suspended particles in an oven the cleaned monolith is ready for use again.

So that the monolith 22 can withstand the given operating and cleaning temperatures, as well as the occurring tensions, it is necessary to manufacture it from a suitable ceramic material. Although for this numerous materials will be suitable for

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Time a ceramic material according to US Pat. No. 3,954,672 used "which was developed for other types of suspended particle filters"
7, line 48, in which a "preferred IT process" guide for the production of extruded monoliths
with open channels "is described.

Starting from this form of monolith will be
one side of the inlet and outlet channels closed in the manner already mentioned. This is done using a cement
used, which is then hardened. As suitable
has a mixture of 71.5 % ground dichroic, the
same material from which the monolith consists, which is passed through a 100-mesh screen, and 28.5 $ colloidal silica (30 ^r / ° Peststoffe and 70 $ of water) has been found "This ^ ement
can be introduced into the ends of the channels in any way, for example through an injection cannula, whereupon it is placed in an oven at a temperature between 90 and 104 ° C. for 8 to 10 hours to set.
Finally, hardening takes place at a temperature of
538 ⁰ O for half an hour «The dichroic can be obtained by grinding rubbish monoliths. The colloidal silica is commercially available and under the name Ludox AS Oollodial
Silica (30fo Solids) from E ₀ I. Du Pont de Memours and Comp. Inc Industrial Chemical Division, Wilmington, Delaware, TJSA
known.

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The invention is preferred to that described However, the embodiment is not restricted, since other forms are also considerable compared to the known types Have advantages, »As an example is therefore a ■ further design shown in FIGS. 3 and 4.

In this case, a motor vehicle chassis 32 has a frame 33 which carries a diesel engine 34 with two rows of cylinders arranged in a V. Each row of cylinders is assigned an exhaust gas collection box 35, both of which are connected to a common suspended particle filter 37. For this purpose, exhaust lines 38 and 39 coming from the exhaust gas collection boxes are each connected to one of the end faces, which extend perpendicularly and are opposite one another. A tube 41 is connected to the outlet of the Schwebeteilchenfilters in the bottom surface and leads to the remaining ^x 'eil of the exhaust system.

The filter element contained in a housing is a monolith 44, which is shown in more detail in Fig. 4. It is the Thermacomb type, which is from the 3M Gompa · ny is produced. This monolith contains several layers of parallel channels, one on top of the other, which extend in the longitudinal direction in each one layer and in the transverse direction in the respective between the the aforementioned layers lying layers. The longitudinal channels 46 are different from those in the transverse direction lying channels 48 separated by porous partition walls 49

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In the exemplary embodiment, the channels 46 are used as inlet channels, while the channels 46 are the outlet channels are. In the arrangement made, in addition to the intermediate walls 49 forming the filter surfaces, between the inlet and outlet channels nor! partition walls 50! are provided between the channels of each layer, which have no filter effect, as they separate channels of the same kind from one another. It will be here so only half of the partition walls are effective as a filter surface, so that a corresponding enlargement of the monolith with the same performance compared to the first building form is necessary »

The monolith 44 is installed in the housing in such a way that the outlet ducts 48 lie in the line and that upper ends are closed, while the lower ends have connection with the pipe 41, the inlet channels 46 are open at both ends and collect the exhaust gases from both exhaust gas collection boxes.

As part of the E _r-making other types of Schwebeteilchenfilters have been used.

Furthermore, a multiform variation of the design of the inlet and outlet channels in the monolith is possible, as shown in IigJ5 & up to k, m, η and ρ.

Pig. 5a shows, for example, a checkerboard-like arrangement of inlet channels 26a and outlet channels 27a »

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The drawing shows that by far the largest! 'Βil the inner surfaces of the ducts act as lter surfaces »

This also applies to the other exemplary embodiments. In the Pig training. 5k , the inlet channels 26b and outlet channels 27b have rectangular cross-sections of the same size, which are separated from one another by the porous partition walls 24b. _o rm, but the partition walls 24c to e likewise always separate an inlet channel from an outlet channel. 5f shows an embodiment in which the inlet channels 26f and the outlet channels 27f have diamond-shaped cross-sections of the same size, which are separated from the intermediate walls 24f.

In the Pig · 5g design, the pile surface is enlarged by the fact that the channels have cross-sections with undulating edges instead of straight edges. Instead of the chessboard-like pattern shown, arrangements according to Figs. 5c to e with corrugated Edges of the cross-sections are taken.

All of these examples have in common that apart from the large pile surface due to the partition walls 24, the quei Sections of inlet channels and outlet channels are of the same size Forms a layer of the separated fibrous tissue particles the remaining cross-section for the gas flow,

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; 9—

~ 12

It can therefore be advantageous to adjust the cross-section of the inlet channels by itself to make it larger than that of the outlet ducts. Here, too, "the filter effect is retained in the area of all partition walls"

The designs according to FIGS. 5h, 5i and 5D are given as examples: “In FIg ₀ Si. are inlet ducts 25h with
hexagonal cross-section in the transverse direction butting together in peaks and arranged perpendicular to this in peaks butting together staggered, the remaining parts having three angular cross-sections forming the outlet channels 27h, their total cross-section being smaller than that of the
Inlet ducts is. The designs according to FIGS. 5i and 5j
show variations of the aforementioned design with regard to the shape of the cross-sections and their assignment to one another.

Another possibility to obtain different cross sections of the inlet and outlet channels while maintaining large filter surfaces is to use the edges of the
To design cross-sections arcuate, wherein they are bent outwards towards the inlet channel and inwardly at the outlet channel. In the ^ auform of FIG. 5k is at a checkerboard like arrangement of the A ~ and outlet ports 26k or 27k, the _o
Bulging made only on the intermediate walls 24k lying in one direction, while those perpendicular to these
Partitions have straight surfaces. A greater difference between the cross-sections can be achieved if the bulge is on according to FIG. 5m. all intermediate

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walls 27m is made _o The same effect is achieved according to FIG. 5 η in that aligned inlet channels 26n triangular cross-section with outwardly curved edges of their cross-section are provided _e Another design according to Jig. 5p provides inlet channels 26p of circular cross-section, the outlet channels 27p being formed by the gussets between the touching inlet channels 26p. The arrangement of the inlet channels 26p could also be made here in a triangular pattern.

In the examples described, the arrangement is always made in such a way that an optimally effective filter surface is created, as is inherent in the design according to FIG. 2. However, the invention is also advantageous when the above examples, other similar arrangements are made, in which not all 2 _w i _SC henwände a F ^ exert lterwirkung formed so similar to the design according to Figo. 4

The terms used in the claims small cross-sections are to be assessed in connection with the statement that the size of the filtering surfaces

2 3

should be less than 78.6 mm $ e cm monolith volume, and that the preferred thickness of the partition walls is in the order of 0.762 mm.

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Claims (2)

Patent attorney ■ '- ■■ ■■' rjpi.-ing. K. Walther 1000BQRUN19 JOH3 WO 20 "November 1980 W-w-3454 General Motors Corporation, Detroit , Michigan, V.St ₀ A. Exhaust gas flow through suspended particle filter for diesel engine Patent claims: / i ~) o A> suspended particles through which the gas flows, for Diesel machines, characterized in that a ceramic monolith (22,4-4) is porous inside Intermediate walls (24,49) which have a plurality of inlet channels (26,46) of small cross-section from adjacent ones Separate outlet channels (27, 48) and through their pores the passage of the exhaust gases from the inlet to the outlet channels allow the filtering surfaces of the intermediate 2 3 walls are not less than 78.6 mm per cnr monolith volume. 2. Sehwebeteilchenfilter according to claim 1, characterized characterized in that the channels extend parallel to one another from one side of the monolith to its other side extend, closed on one side and open on the other side, and that each is a group of Inlet channels (26) and outlet channels (27) are formed on opposite sides of the monolith are closed, and that each partition (24) separates an inlet channel from an outlet channel and a filter surface for the exhaust gases whose porosity is chosen 130025 / 0S91 -2- 3043905 is that a substantial part of the suspended particles from the passing exhaust gases τοη retained the partition walls will" 3 <, Schwet> particle filter naoh claim 1 or 2, characterized in that the partitions (24,49) have an average porosity of not less than 10 $ with an average pore size between 2 and 15 microns and individual pore sizes between 0.5 and 70 microns « 4 “Suspended particle filter according to one of the preceding Claims, characterized in that the one ends of the inlet and outlet channels through a highly heat-resistant Material are closed. 130025/0531 —3 — ι