DIESEL PARTICULATE FILTER
A diesel particulate filter assembly having a housing and a filter structure disposed within the housing for trapping particulate material in received exhaust gas as such received exhaust gas passes through the housing along a longitudinal axis of the housing. The filter structure has walls of particulate collecting, gas passing material. The walls pass portions of the exhaust gas while trapping particulate material in such passing exhaust gas. The walls are disposed the oblique to the direction of the received exhaust gas.
This disclosure generally to exhaust gas treatment systems and more particularly to diesel particulate filters used in such systems.
BACKGROUNDAs is known in the art, most current diesel exhaust gas treatment systems today include a DOC (Diesel Oxidation Catalyst) followed by a DPF (Diesel Particulate Filter). The DPF includes a substrate (sometimes referred to as a substrate brick or brick) with the outlet end closed on the inlet channel and the inlet end closed on the outlet channel. Exhaust gas flows through the inlet channel, crosses the wall of cells, and then exits through the outlet channel. The particles are filtrated in the inlet channel.
As is also known in the art, particulate filters are used in the exhaust systems of internal combustion engines, especially diesel engines, (diesel particulate filters or DPF) to trap and remove particulate matter which is primarily formed of carbon based material. As the engine exhaust passes through the DPF, the particulates are trapped in the filter and accumulate over time. This leads to an increase in the resistance of the exhaust gas flow through the DPF, and therefore, to an increase in the backpressure on the engine. This increase in backpressure has an adverse effect on engine operation, and especially on fuel consumption. In order to reduce backpressure to acceptable levels, the DPF is periodically regenerated by burning off the accumulated particulates, most of which are combustible.
As is also known in the art, a traditional cordierite or SiC DPF system needs to under going a regeneration process to burn out soot collected on the DPF wall surface. A few problems are associated with this procedure: 1. A fuel penalty because diesel fuel is injected either through post injection or down pipe injection to generate high exhaust temperature. Usually fuel penalty is in the range of 3 to 5%; 2. Unevenly distributed soot resulted from poor flow uniformity will lead to high temperature gradient inside DPF substrate, and cause durability issue such as ring-off-crack failure; and 3. Very low or even negative NOx conversion efficiency is found during DPF regeneration, usually takes more than 10 minutes. This is becoming an issue for level III emission requirements.
SUMMARYIn accordance with the present disclosure, a diesel particulate filter assembly is provided having: a housing and a filter structure disposed within the housing for trapping particulate material in received exhaust gas as such received exhaust gas passes through the housing along a longitudinal axis of the housing. The filter structure has walls of particulate collecting, gas passing material; such walls passing portions of the exhaust gas while trapping particulate material in such passing exhaust gas. The walls are disposed oblique to the direction of the received exhaust gas.
In one embodiment, a diesel particulate filter assembly is provided having a housing and a filter structure disposed within the housing for trapping particulate material in received exhaust gas as such received exhaust gas passes through the housing along a longitudinal axis of the housing. The filter structure forms a plurality of channels separated by walls of particulate collecting, gas passing material. The walls pass portions of the exhaust gas from one of the channels to another adjacent one of the channels while trapping particulate material in such passing exhaust gas. The walls are disposed oblique to the direction of the received exhaust gas.
In one embodiment, a diesel particulate filter assembly is provided having a housing having an inlet for receiving an inlet flow of exhaust gas from a diesel engine and a filter structure disposed within the housing. The filter structure is provided for trapping particulate material in the received exhaust gas as such received exhaust gas passes in an outlet flow through an outlet of the housing with the inlet flow and the outlet flow being disposed along a longitudinal axis of the housing. The filter structure forms a plurality of channels for passing portions of the received exhaust gas, such channels being separated by porous walls of particulate collecting, gas passing material, such walls passing portions of the exhaust gas from one of the channels to another adjacent one of the channels while trapping particulate material in such passing exhaust gas. The separating walls of each one of such channels is disposed oblique to the direction of the received exhaust gas.
In one embodiment, the channels have an inlet channel section and an outlet channel section, the inlet channel section being upstream of the outlet channel section.
In one embodiment, the assembly has a main channel in addition to the plurality of channels, such main channel being disposed between an inner wall of the housing and the filter structure.
In one embodiment, the particulate collecting, gas-passing material is paper.
In one embodiment the filter structure is removable mounted within the housing.
The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTIONReferring now to
The filter structure 18, here porous paper, forms a plurality of channels 30, 32, 34 for passing portions of the received exhaust gas flow 16. The channels 30, 32 and 34 have an inlet for receiving the gas flow 16 and an outlet for exhausting the filtered gas flow 20, the inlet being upstream of the outlet.
The channels 34, an exemplary one being shown more clearly in
More particularly, the filter structure 18 has a main channel, i.e., channel 30 in addition to the plurality of channels 32, such main channel 30 being disposed between an inner wall 42 of the housing 12 and the filter structure 18. Exhaust gas can go anywhere to pass the filter wall 40 depends on how much pressure loss it will experience. The flow is always towards the path having the least pressure drop. If all of the exhaust gas passed through at the end of top channel 30, there will be great pressure loss (soot deposit will creates even much higher pressure loss as time goes on); therefore a portion of the exhaust gas enters the channels 34, more particularly the inlet channel section 341 and passes through the separating wall 40S to the adjacent outlet channel section 340, as indicated by the arrows 35.
As noted above, the particulate collecting, gas passing material, i.e., walls 40, is paper. Further, the filter structure 18 is removable mounted within the separable two-piece housing 12 when it is required to change the filter structure 18. Here, for example, for 0.2 m(height)×0.25 m(width) filter with 100 folders (channels) Total surface area will be: 100×0.2×0.25=5 m2, the porosity of fiber paper can be larger than 80%, DPF trap efficiency can reach 99.9% with much lower pressure loss than traditional DPF.
Referring now to
The channels 34 may be fastened together in any convenient manner such as with metal bands, not shown, as are used to fasten together the slats in a wooden rain barrel.
A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.
Claims
1. A diesel particulate filter assembly, comprising:
- a housing;
- a filter structure disposed within the housing for trapping particulate material in received exhaust gas as such received exhaust gas passes through the housing along a longitudinal axis of the housing, such filter structure having walls of particulate collecting, gas passing material, such walls passing portions of the exhaust gas while trapping particulate material in such passing exhaust gas, the walls being disposed oblique to the direction of the received exhaust gas.
2. A diesel particulate filter assembly, comprising:
- a housing;
- a filter structure disposed within the housing for trapping particulate material in received exhaust gas as such received exhaust gas passes through the housing along a longitudinal axis of the housing, such filter structure forming a plurality of channels separated by walls of particulate collecting, gas passing material, such walls passing portions of the exhaust gas from one of the channels to another adjacent one of the channels while trapping particulate material in such passing exhaust gas, the walls being disposed oblique to the direction of the received exhaust gas.
3. A diesel particulate filter assembly, comprising:
- a housing having an inlet for receiving an inlet flow of exhaust gas from a diesel engine;
- a filter structure disposed within the housing for trapping particulate material in the received exhaust gas as such received exhaust gas passes in an outlet flow through an outlet of the housing with the inlet flow and the outlet flow being disposed along a longitudinal axis of the housing, such filter structure forming a plurality of channels for passing portions of the received exhaust gas, such channels being separated by porous walls of particulate collecting, gas passing material, such walls passing portions of the exhaust gas from one of the channels to another adjacent one of the channels while trapping particulate material in such passing exhaust gas, the separating walls of each one of such channels the walls being disposed oblique to the direction of the received exhaust gas.
4. The filter assembly recited in claim 3 wherein the channels have an inlet channel section and an outlet channel section, the inlet channel section being upstream of the outlet channel section.
5. The filter assembly recited in claim 2 wherein the assembly has a main channel in addition to the plurality of channels, such main channel being disposed between an inner wall of the housing and the filter structure.
6. The filter assembly recited in claim 1 wherein the particulate collecting, gas passing material is paper.
7. The filter assembly recited in claim 6 wherein the filter structure is removable mounted within the housing.
Type: Application
Filed: May 26, 2009
Publication Date: Dec 2, 2010
Inventor: Xiaogang Zhang (Novi, MI)
Application Number: 12/471,809
International Classification: F01N 3/02 (20060101);