DE2853720A1 - Compression ignition engine exhaust manifold - has return channel near engine port, part of whose wall is formed by ceramic fibre filter for carbon separation - Google Patents

Abstract

The exhaust gas return channel (3) provides engine reentry via a filter. In the direct vicinity of the engine (2) outlet part is provided the return channel assembly within the exhaust manifold (1) at least part of the channel wall (6) being formed by a mechanically supported filter mat (7) made of ceramic fibres and intended to separate carbon particles. The residue heat of the exhaust gases is sufficient to burn the separated carbon particles. Preferably the return channel is U-shaped or semi-circular the filter mat forming an interface with the manifold inside. The filter mat support may be a perforated plate.

Description

Exhaust manifold for air-compressing combustion

engines The invention relates to an exhaust manifold arranged close to the engine for air-compressing internal combustion engines, with a return duct for exhaust gas, which Is fed back into the internal combustion engine via a soot filter on the inlet side.

Eo i an exhaust gas cleaner known in particular for internal combustion engines (DE-PS 831 177), which according to the cyclone principle with reversal of the gas flow, the is discharged centrally, works, whereby the air vortex before it is natural Has reached the turning point, forced to change direction by an insert floor will and the entrained liquid and solid components through slots provided in the insert base into an underlying der Reaching the recovery space deprived of the fluid. For this in a vertical position - arranged exhaust gas purifiers must be removed from the exhaust gas from time to time Components are removed manually.

It is also a soot filter with exhaust gas flow from air-compressing Internal combustion engines known (PA -P 27 50 960.0) become, which by a near the outlet the internal combustion engine arranged cylindrical filter housing to the radial or Inlet nozzles extending tangentially from the internal combustion engine are connected, in which at a distance from the circumferential wall in a hollow cylindrical shape ceramic Fiber material is arranged, which consists of an outer layer of loose ceramic fiber mat exists, and from which the cavity within the fiber material in the axial direction the exhaust line is connected.

Due to the close proximity of the soot filter to the internal combustion engine the hot exhaust gases are filtered immediately and the glowing soot particles can ignite the other soot that has adhered to the ceramic fiber material and burn afterwards. But because all the exhaust gases flow through the filter must and the soot particles are then retained as much as possible soon a certain counterpressure arises, which not only leads to a drop in performance the internal combustion engine, but also to increased soot formation in the internal combustion engine itself leads - whereby any soot formation should be avoided as far as possible.

The object of the invention is to arrange and so a soot filter to train that soot filtered out of the exhaust gas recirculation amount for burning off of the soot relevant physical operating states of the internal combustion engine a automatic burning off of the soot occurs and that when filtering out the soot the Build-up of a back pressure is largely avoided.

This object is achieved according to the invention in that the return channel in the immediate exit area of the exhaust gases emerging from the internal combustion engine is arranged within the exhaust manifold and that at least part of the Channel wall through a mechanically supported fiber-ceramic filter mat for filtering out is formed by soot on which the residual heat of the impinging exhaust gas retained soot can be burned off independently.

Due to the close arrangement of the actual soot filter on the internal combustion engine does not become a source of external ignition for cleaning the filter by burning off the filtered soot needed, because the still glowing soot particles in the exhaust gas are the ones on the ceramic Ignite and burn the soot distributed in the filter material. The uniform achieved here Local distribution of the soot on the filter material results in only a small amount Heat conversion, so that overheating during the burning process can be avoided. By the arrangement of the return duct inside the exhaust manifold is only used for the Recirculation of the required amount of exhaust gas is filtered, while the rest is released into the atmosphere escapes So no noticeable counterpressure can build up.

According to a further feature of the invention, the return channel in the Cross-section U-shaped or semicircular and to the interior of the exhaust manifold be limited by a flat filter mat.

The return channel can, however, also have a circular cross-section and bounded to the interior of the exhaust line by a tubular filter mat be.

In the former case, the hot exhaust gas flow hits the directly Filter mat, while in the other case the filter mat is partly directly in the hot Exhaust gas flow lies and is partly washed around by this.

Furthermore, the filter mat can be arranged between each perforated plate and be supported by it.

This makes the filter less sensitive to vibrations and hard bumps. In addition, between the filter mat and the downstream side the Perforated plate supporting the filter mat for finer meshed support of the same at least a wire mesh can be provided.

This fine-meshed support of the filter mat becomes longer Lifetime of the filter reached.

Finally, between the filter mat and the downstream side the Perforated plate supporting the filter mat for finer meshed support of the same at least a wire mesh can be provided.

This arrangement is also used for protection and longer preservation the filter mat.

Using an exemplary embodiment shown in the drawing the finding is to be explained in more detail.

The figures show: FIG. 1 a schematically illustrated exhaust manifold according to the invention, FIG. 2 with a cross section through an exhaust manifold a U-shaped return duct, FIG. 3 shows a cross section through an exhaust manifold with a tubular return channel, 4 shows a filter mat arrangement According to FIGS. 2 and 5, a filter mat arrangement according to FIG. 3.

The exhaust manifold 1 shown schematically in FIGS arranged in the immediate vicinity of an internal combustion engine 2 and consists of one with regard to heat dissipation to the outside, insulated, essentially cylindrical housing 3, which includes an exhaust gas recirculation channel 5 held inside by a web 4. At least part of the duct wall 6 consists of a mechanically supported one Barrel ceramic filter mat 7,> wolche for filtering out soot from the exhaust gas is used, which is fed back into the internal combustion engine 2. The mechanical support the filter mat 7 is done by means of a perforated plate he stere 8 on which the filter mat 7 is connected by a fine wire mesh 9 and a coarser one Wire mesh 10 held and finally by a second perforated plate 11 inward to the channel center 12 is supported (Fig. 4 and 5).

The exhaust gases emitted by the internal combustion engine 2 are only in filtered to the extent necessary for the return, the unneeded Part of the exhaust gases can escape into the free atmosphere via the exhaust pipe 13. This avoids the creation of a significant counter pressure.

In phases of operation with high levels of soot (low excess air), I can the soot is deposited on the filter mat 7 and immediately or in phases of high exhaust gas afterburning temperature independently and with little delay.

The return channel can have a U-shaped or semi-circular cross-section trained (flat flow through the filter) or it can also be in cross-section be designed circular.

In the latter case, the filter mat 7 is partly directly in the hot Exhaust gas flow, in part it is washed around it.

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Claims (6)

Claims 1. Exhaust manifold arranged close to the engine for air-compressing Internal combustion engines, with a return duct for exhaust gas, which is via a return filter is fed back into the internal combustion engine on the inlet side, d u r c h e k e n It is indicated that the return channel (51 in the immediate exit area of the exhaust gases emerging from the internal combustion engine (2) within the exhaust manifold (1) is arranged and that at least part of the channel wall (6) by a mechanical supported. fiber-ceramic filter mat (7) is formed to filter out soot, on the soot retained by the residual heat of the impacting exhaust gas is burnable. 2. Exhaust manifold according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the return channel (5) is U-shaped or semicircular in cross section formed and to the interior of the exhaust manifold (1) through a flat filter mat (7) is limited. 3. Exhaust manifold according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the return channel (5) is circular in cross section and to the interior of the exhaust manifold (1) through a tubular filter mat (7) is limited. 4. Exhaust manifold according to claim 1 and claim 2 or 3, d a d It is noted that the filter mat (7) is sandwiched between a perforated plate (8, 11) is arranged and supported by this. 5. Exhaust manifold according to one or more of claims 1 to 4, d a d u r c h e k e n n n z e i c h n e t that between the filter mat (7) and the Perforated plate (11) supporting the filter mat (7) on the downstream side for finer-meshed Support of the same at least one wire mesh (9,10) is provided. 6. Exhaust manifold according to claim 5, d a d u r c h g e k e n n z e i c h e t that two wire meshes with different machine widths (9, 10) are provided, the fine-meshed wire mesh (9) directly the filter mat (7) is supported.