Electronic power steering method and apparatus

A power steering control unit electrically coupled to a vehicle steering assist motor for energizing said motor comprising:

• means for monitoring a turning torque applied through a vehicle steering wheel by a user to a vehicle steering assembly;
• programmable memory means for storing one or more parameters corresponding to a desired motor response to said torque;
• control means coupled to each of said means for monitoring and said programmable memory means for storing;
• said control means including means for determining a motor assist energization sequence based upon the torque applied by said user and said parameters stored in the programmable memeory means, said control means also including means for altering said one or more parameters stored in the programmable memory to adjust the motor assist;
• and
• means coupleable between said control means and said steering assist motor responsive to said control means for energizing said motor.

In a power steering system having an electric motor coupled to a vehicle steering system for assisting an operator in maneuvering the vehicle, apparatus comprising:

• a controller for sending pulse width modulated energization signals to said electric motor, said controller having a plurality of inputs for monitoring the status of said vehicle steering system with at least one input indicating the status of the motor;
• power circuitry for energizing motor field and armature windings, said power circuitry including a switch for coupling said power circuitry to an energy source;
• means coupled to said controller for opening said switch in response to a control output from said controller to de-energize said power circuitry in the event the status of said motor deviates from the status the controller dictates with the pulse width modulated energization signals;
• and
• said controller having means to modify the pulse width modulated energization signals rather than de-energize the motor in response to sensed conditions in the vehicle steering system indicated by the plurality of inputs.

In a motor assisted power steering system having a direct current assist motor with fixed and armature windings, a method for energizing said motor comprising the steps of:

• sensing a torque applied by a user to said steering system through a steering mechanism;
• calculating a preferred motor energization sequence based upon said torque, said calculating step including a substep of comparing said torque with a threshold torque beneath which no assist is provided;
• energizing said motor field windings if a torque greater than said threshold is applied;
• simultaneously with said energizing step beginning a pulse width modulation of said armature windings with a duty cycle related to said torque;
• and
• continuing to sense said torque and compare the applied torque with said threshold to determine when said windings are to be de-energized.

In a power steering unit having a motor coupled to a vehicle steering system to assist an operator in maneuvering the vehicle, control apparatus comprising:

• means for monitoring the speed of said vehicle;
• means for monitoring a torque applied by said operator through a vehicle steering mechanism to said steering system;
• at least one programmable controller energized from a vehicle battery for calculating a motor energization sequence based upon said speed and said torque and for energizing said motor in accordance with said sequence,
• a non-volatile memory unit for storing sets of constants for use by the programmable controller in calculating a preferred motor energization;
• and
• switching means coupleable with said at least one controller for selecting a specific set of constants for use by said controller in energizing said motor.

A power steering control unit electrically coupled to a steering assist motor for energizing said motor comprising:

• means for sensing a turning torque applied through a vehicle steering wheel by a user to a vehicle steering assembly;
• memory means for storing one or more parameters corresponding to a desired motor response to said torque;
• control means coupled to each of said means for monitoring and said means for storing;
• said control means including means for determining a motor assist energization sequende based upon the torque applied by said user and said stored parameters;
• means coupleable between said control means and said steering assist motor responsive to said control means for energizing said motor;
• and
• means for monitoring performance of said control unit and coupling signals indicative of said performance to said control means for storage in said memory means.