Appeal No. 2006-1094
Application No. 09/976,788
Cowan’s control system operates as follows: An electronic processor 70
receives input signals from various sensors that measure engine and vehicle
operating conditions. The output of the microprocessor is transferred to solenoid
64. The solenoid valve controlled by solenoid 64 is calibrated to receive the
control pressure of the solenoid output to establish a pressure that will determine
the controlled slip of the clutch (col. 6, ll. 33-48).
One of the input signals to the processor 70 is a throttle position signal
received by a position sensor 74. Additionally, an engine speed sensor 76 in the
form of a profile and ignition pickup (PIP) delivers an engine speed signal to the
processor 70.
It is quite apparent from the above that Cowan’s control system adjusts the
slip of the torque converter using a setpoint or desired slip, which depends upon
information from, inter alia, an engine speed sensor (engine RPM) whereby the
bypass clutch capacity is adjusted to a value that is necessary to achieve the desired
slip “at any given torque” (col. 4, ll. 4-5). Furthermore, the solenoid output signal
is adjusted during each background control loop of the processor in accordance
with the new torque condition and the desired slip is determined by the actual slip
and the final target slip value, causing an exponential decay in the slip as the final
target slip is approached. In other words, Cowan’s control system adjusts the slip
of the torque converter by calculating a desired slip, which is continuously adjusted
during each control loop of the processor to cause an exponential decay in the slip
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Last modified: November 3, 2007