Appeal No. 2002-0797
Application No. 08/900,977
fuel vapor collection canister to the intake manifold of the
vehicle’s engine. According to Cook ‘785, it was difficult at
the time of the Cook ‘785 patent to design a purge system that
possessed both precise low-flow control and the capacity to
handle much larger purge flow rates (col. 1, lines 30-43). With
reference to Figure 1, Cook ‘785 proposes to overcome this
deficiency by providing a purge system that includes an
electrically controlled fluid flow control valve 12 disposed in a
first passageway 38 between the collection canister and the
intake manifold and a normally-closed, vacuum-actuated valve 14
disposed in a second passageway 40 in parallel with the first
passageway between the collection canister and the intake
manifold. As explained by Cook ‘785 in the paragraph spanning
columns 1 and 2, the normally-closed vacuum-actuated valve
14 operates to open the second passageway to fluid flow only when
the control signal for the control valve 12 exceeds a certain
minimum. Thus, when higher fluid flow is demanded, the vacuum-
actuated valve 14 opens to allow the second passageway 40 to
route a portion of the fluid flow around the control valve 12.
Figure 5 illustrates a further embodiment wherein the passageway
that contains the electrically controlled fluid flow valve also
includes a pressure regulator 62B “for the purpose of
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