Exhaust gas cleaner

An exhaust gas cleaner comprising:

• (a) at least one planar filter element for trapping particulate matter in an exhaust gas, said filter element being made of a heat-resistant and electrically insulating material and having a hole therein;
• (b) at least a pair of planar electrodes each having substantially the same shape and area as said filter element and having a hole therein of the same size as the hole in said filter element, said electrodes being stacked alternately with said at least one filter element with the holes therein in alignment so as to define a gas-flow path;
• (c) a housing enclosing a stack of said at least one filter element and said electrodes and having an inlet aligned with said gas-flow path for introducing an exhaust gas which flows through said at least one filter element in a direction substantially parallel to the laminate surfaces of its adjacent electrodes, and an outlet for discharging filtered exhaust gas;
• and
• (d) means for applying between adjacent electrodes of said stack a voltage sufficient to cause electric current to flow through particulate matter trapped in said at least one filter element only when sufficient particulate matter to conduct electric current between said electrodes is trapped, which generates heat for burning electrically conductive and burnable particulate matter trapped in said filter element and automatically stops flowing when sufficient particulate matter has been burned that not enough remains to conduct current between said electrodes.