The exhaust gas purification device has a first chamber having an exhaust
pipe inlet, an ambient air inlet, and an exhaust gas outlet. A Venturi is
arranged within the chamber, having an inlet end communicating with an
ambient air inlet, a throat, and an outlet end communicating with an
exhaust gas outlet. The Venturi has an exhaust gas inlet between its
inlet end and its outlet end, receiving exhaust gas from within the
chamber, directed generally towards the outlet end of the Venturi, so
that ambient air and exhaust air are mixed in passing through the Venturi
to its exhaust gas outlet. A perforated pipe within the first chamber
receives the exhaust gas, and the exhaust gas escapes there from via the
perforations, into the chamber and thence to the Venturi. A second
chamber, having a catalytic substrate assembly mounted therein, receives
the mixed ambient air and exhaust air from the exhaust gas outlet of the
Venturi, and has an exhaust pipe outlet.