Bifilar diesel exhaust filter construction using sintered metal fibers
A diesel particulate filter construction, for filtering particulate from a flow of exhaust, includes a first layer of electrically resistive metal filter material in line with the flow of exhaust with particulate therein and a second layer of electrically resistive filter material which is also in line with the flow of exhaust with particulate therein. The layers are pleated cylinders concentrically positioned relative to one another. Current from a power supply is routed through the first layer and the second layer, which are electrically connected in series to one another. The layers are positioned so that exhaust flows through both the layers. Sufficient heat is generated by the flow of current through the layers to generate heat to, in turn, burn off entrapped particulate. The layers may be made of made of different materials of different fiber sizes or coated with different catalysts to generate different amounts of heat from one another to improve the filtration characteristics of the particulate filter construction.
1. A diesel particulate filter construction for filtering particulate from a flow of exhaust, comprising:
a first layer of electrically resistive filter material being positioned substantially transverse to the flow of exhaust with particulate therein and having a first end and a second end; the first end of the first layer providing a first terminal;
a second layer of electrically resistive filter material being positioned substantially transverse to the flow of exhaust with particulate therein and having a first end and a second end; the first end of the second lever providing a second terminal; the second layer being electrically connected to the first layer with the second end of the first layer connected to the second end of the second layer;
means attached to the first terminal of the first layer and the first terminal of the second layer for applying an electrical current through the first layer and the second layer in series to heat the first layer end the second layer above the combustion point of entrapped diesel particulate; the first layer and the second layer being positioned such that when an electrical current is applied through the first layer and the second layer, sufficient heat is generated to bum off entrapped particulate.
2. The diesel particulate filter construction of claim 1 , wherein the first layer and the second layer are substantially in parallel with one another and in line with the exhaust flow.
3. The diesel particulate filter construction of claim 1 , wherein the first layer is manufactured of a different material than the second layer.
4. The diesel particulate filter construction of claim 3 , wherein the first layer has a different resistivity than the second layer.
5. The diesel particulate filter construction of claim 3 , wherein the first layer generates a different amount of heat than the second layer.
6. The diesel particulate filter construction of claim 1 , wherein the first layer and the second layer are pleated.
7. The diesel particulate filter construction of claim 2 , further comprising: an electrically insulative layer disposed between the first layer and the second layer.
8. The diesel particulate filter construction of claim 2 , wherein the first layer is cylindrical in configuration and the second layer is cylindrical in configuration; the second layer being concentrically positioned about the first layer.
9. The diesel particulate filter construction of claim 1 , wherein the first layer and the second layer are made of sintered metal fibers.
10. The diesel particulate filter construction of claim 7 , wherein the electrically insulative layer is made of a material selected from the group consisting of ceramic and silica.
11. The diesel particulate filter construction of claim 1 , further comprising: catalyst material coated on the first layer.
12. The diesel particulate filter construction of claim 1 , further comprising: catalyst material coated on the second layer.
13. The diesel particulate filter construction of claim 1 , further comprising: catalyst material coated on the first layer; and catalyst material coated on the second layer.
14. The diesel particulate filter construction of claim 1 , wherein the means attached to the first terminal of the first layer and the first terminal of the second layer for applying an electrical current is a power supply.
15. The diesel particulate filter construction of claim 9 , wherein the electrically resistive metal filter material is a sintered alloy of Iron, Chromium and Aluminum.
16. The diesel particulate filter construction of claim 1 , wherein the electrically resistive filter material resist oxidation, carburization and sulphidition at temperatures up to 1100 degrees Centigrade.
17. The diesel particulate filter construction of claim 1 , wherein the first layer and the second layer are each configured to be regenerable within 30 to 120 seconds.
18. The diesel particulate filter construction of claim 1 , further comprising:
a third layer of filter material in line with the flow of exhaust with particulate therein; the third layer of filter material being a passive filter layer and not connected to the means attached to the first layer and the second layer for applying an electrical current.