Appeal No. 1998-1004
Application 08/401,984
I have discovered that when a heater, such as a coil heater, is used in an exhaust gas
treatment apparatus without benefit of protection of a plate, the heater may prematurely fail.
During use, soot composed of particles trapped by the filters of the apparatus is back-
flowed into the process portion and onto the heater. Such soot is formed of carbon and
hydrogen containing materials. If the heater is directly exposed to those materials, it oxidizes
due to overheating caused by burning of the carbon containing materials. Furthermore, the
hydrogen containing materials function to accelerate oxidation of the heater, which also
contributes to premature breakage and failure of the heater.
In contrast, according to the claimed invention a plate is provided in combination with a
heater, whereby the heater is not directly exposed to the carbon and hydrogen containing
materials (such as hydrocarbons) and premature failure of the heater is prevented.
Appellant Ichikawa further states in ¶ 4 that “none of the cited prior art discloses or suggests our
claimed invention or its attendant advantages;” that the “prior art does not teach to one of ordinary skill
in the art, and does not teach to me personally how to make our claimed invention;” and that the
claimed invention “as a whole would not have been obvious at the time the invention was made” to one
of ordinary skill in the art.
We have carefully considered appellant Ichikawa’s testimony in light of the knowledge in the
prior art as set forth in Levendis and the summary of the invention disclosed therein (cols. 1-2). The
composition of the particulate matter in exhaust gas from diesel engines was well known to include,
inter alia, soot particulate which is “‘sticky’ and adheres quite readily to” surfaces, thus accumulating
on the surface of ceramic traps or filters containing embedded resistive filaments whereon it formed hot
spots during the high temperature regeneration of the ceramic traps or filters (col. 1). The oxidation of
the particulate matter in a burner away from traps or
filters in the apparatus of Levendis is conducted at a lower temperature (col. 2). However, even so,
one of ordinary skill in this art would have reasonably observed during operation of the Levendis
apparatus that the soot particulate is “sticky” and adherent even at the lower temperature, thus
accumulating on the surfaces of the burner including any exposed resistive filaments or coils of the
heating element, such as shown in Levendis FIG. 5B, with the obvious result that the expected residue
remained on such elements after the accumulated hydrocarbon particulates have been burned.
declaration. See 37 CFR § 1.195; Manual of Examining Practice and Procedure § 716 (6th ed., Rev.
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