Eaton Corporation

William L Kelledes

Walter K O'Neil

Rick L Boyer

Glenn Clark Fortune

Don K St John

A method of controlling a viscous fluid coupling (15) in which, when the vehicle engine (E) is operating at low speeds, if the speed of rotation (SF) of the fan exceeds a predetermined speed limit (L3), the input signal (29) to the coupling is modified to move the valve member (49) toward a closed position (FIG. 3A). This action reduces the occurrence of an overfill condition, thus reducing undesired fan noise when the engine again accelerates. Another aspect of the invention is to sense the speed (SE) of the engine, and whenever the sensed speed (SE) is high enough that operation in an excess slip heat region (ESH) is possible, compare the demanded fan speed (29) to the lower limit (CHP) of the slip heat region. Whenever the demanded fan speed exceeds the limit, the input signal (29) to the coupling is modified to operate the coupling at a speed safely above or below the slip heat region (ESH) depending on the state of control inputs such as engine temperature.

Viscous fan drive system logic

An electrically actuated shifting mechanism includes a reversible rail select electric motor and a reversible in-gear electric motor. Three groups of switches are provided to effect one-at-a-time operation of the motors with a center group of switches being used to effect operation of either the rail select or the in-gear motor and to determine the direction of operation of the motor. In one embodiment of the invention, the motor control circuitry also controls the operation of a main clutch motor. Four groups of switches are used to effect operation of the in-gear, rail select and clutch motors in desired directions. Pulse width modulation is used to effect simultaneous and out-of-phase operation of the in-gear and main clutch motors.

Motor controls

The present invention maintains constant torque in an inverter driven AC induction motor during variations in rotor temperature. It is known that the torque output of a given AC induction motor is dependent upon rotor temperature. At rotor temperatures higher than the nominal operating condition the rotor impedance increases, reducing the rotor current and motor torque. In a similar fashion, the rotor impedance is reduced resulting in increased rotor current and motor torque when the rotor temperature is lower than the nominal operating condition. The present invention monitors the bus current from the DC supply to the inverter and adjusts the slip frequency of the inverter drive to maintain a constant motor torque. This adjustment is based upon whether predetermined conditions implying increased rotor temperature or decreased rotor temperature exist for longer that a predetermined interval of time.

Motor torque compensation of an induction electric motor by adjusting a

A torque transducer (10) generates a signal representing torque applied to an input shaft (12) to the transducer. The input shaft is resiliently connected to an output shaft (14), permitting limited relative rotation between the two which is sensed by the selective shunting of an electromagnetic field. Multiple fields and shunting devices (76 and 78) are provided which coact complementarily (in shunting effect) to provide a usable signal throughout an entire range of operation. In application, the transducer is intended for electrically assisted vehicle power steering systems.

Torque transducer

An electrical power assisted steering system for a vehicle. The system includes a battery, having two terminals at different voltages and a center tap, and a bidirectional electric power assist motor having two terminals, one terminal being connected to the center tap of the battery. In an electric vehicle, said battery would be the traction battery. A control circuit responds to movement of the vehicle's steering wheel to generate a pulse width modulated (PWM) signal to drive the motor to assist in steering. The pulse widths are directly proportional to the driver's rotational displacement of the steering wheel and the amount of current flowing through the motor and inversely proportional to the speed of the vehicle. The PWM signal is applied to a selected one of two driving transistors, the first of which is connected between one of the terminals of the battery and the free terminal of the motor, the other of which is connected between the other terminal of the battery and the free terminal of the motor. Upon receipt of the PWM signal, the selected driving transistor connects the motor to its associated terminal of the battery to cause the motor to turn in a desired direction and deliver torque proportional to the width of the pulses. Also disclosed are monitoring circuits which monitor the operation of the control circuit and disconnect the motor from the battery when a malfunction is detected.

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Brighton, MI, United States of America

William L Kelledes