Appeal No. 98-1310
Application 08/368,685
adding supplemental air, at one of the
engine and a point downstream of the trap,
to the exhaust during the hydrocarbon
operating desorption period of the trap to
maintain a substantially stoichiometric
air/fuel balance in the exhaust gases
flowing into the downstream catalyst zone.
There is nothing in Burk which either teaches or suggests such
a limitation. With respect to the embodiment of Fig. 11, Burk
on page 11 states that air is injected into the gas stream in
amounts sufficient to provide 10 volume percent of O in the
2
gas stream for 5 seconds after each minute of stoichiometric
operation. Although Burke does not expressly state why air is
being injected in the embodiment of Fig. 11, it is apparently
for the same reason set forth in the embodiment of Fig. 4,
namely,
to promote the oxidation of hydrocarbon pollutants in the
exhaust gas stream which in turn heats the exhaust gas stream
because of the exothermic nature of the oxidation reaction
(see page 29, lines 2-7). Indeed, the examiner even concedes
that Burk "provides no disclosure of controlling supplemental
air to the exhaust in response to sensing the exhaust air/fuel
ratio and controlling the air for stoichiometric oxidation of
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