Appeal No. 2004-0575
Application 09/206,005
As noted on page 1 of the specification, appellant’s
invention relates to a transmission fluid cooling system and,
more particularly, to a cooler-bypass unit having a banjo bolt
incorporating a relief valve. As can be seen in Figure 1 of the
application drawings, appellant’s cooler-bypass unit (40) is
connected between the transmission fluid line (26) exiting the
transmission case (22) and the fluid return line (30). The
cooler-bypass unit has a banjo bolt relief valve (44) at a first
end (45) of bypass fluid line (42) and a return banjo bolt (46)
at an opposite end (47) of the bypass line. Operation of the
cooler-bypass unit (40) is described in the following manner on
pages 7 and 8 of the application:
In operation, when the engine is first started, the
transmission fluid is cool and viscous. The transmission
fluid is pumped through the transmission case 22 into the
transmission fluid cooler 24, but the cool, viscous
transmission fluid does not flow easily through the
transmission fluid cooler 24. This causes back pressure to
build up in the supply line 26 and in the annular cavity 56
of the banjo bolt relief valve 44. When the transmission
fluid is sufficiently cool, this pressure is sufficient to
overcome the spring bias of the ball 72 against the valve
seat 71, thereby permitting transmission fluid to flow into
the body portion 50 of the banjo bolt relief valve 44 and
directly into the transmission fluid return line 30 back to
the transmission case 22, bypassing the transmission fluid
cooler 24.
When the transmission fluid heats and becomes less
viscous, the transmission fluid flows more easily through
the transmission fluid cooler 24, thereby reducing the
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