Method and apparatus for detecting a motor stall condition in an electric assist steering system

An apparatus for detecting an over-use condition of an electric assist motor in a vehicle electric assist steering system, comprising:

• steering means for steering the steerable wheels of a vehicle;
• torque command circuit means for sensing the steering torque applied to the vehicle steering wheel and for providing a torque command signal indicative thereof;
• and
• over-use detection means for integrating said torque command signal over time and for providing an overuse signal in response to said integrated torque command signal.

A method for detecting a stall condition of a motor in an electric assist steering system, comprising the steps of:

• (a) providing a steering means for steering the steerable wheels of a vehicle;
• (b) providing an electric assist motor connected to said steering means for, when energized, providing steering assist;
• (c) sensing the steering torque applied to a steering wheel of said vehicle and providing an applied torque signal indicative thereof;
• (d) monitoring said applied torque signal and providing a torque command signal to said motor in response thereto, said motor being energized in response to said torque command signal;
• (e) sensing commutation of said motor and providing a commutation signal indicative thereof;
• (f) monitoring said torque command signal and said commutation signals;
• and
• (g) providing a stall signal in response to both said torque command signal and said commutation signal.

A method for detecting an over-use condition of an electric assist steering motor, comprising the steps of:

• (a) providing a steering means for steering the steerable wheels of the vehicle;
• (b) sensing the steering torque applied to a steering wheel of said vehicle;
• (c) providing a torque command signal in response to said sensed applied steering torque;
• (d) integrating said torque command signal;
• and
• (e) providing an over-use signal in response to said integrated torque command signal.

An apparatus for detecting a fault condition of an electric assist motor in a vehicle electric assist steering system, comprising:

• steering means for steering steerable wheels of the vehicle, said steering means being responsive to steering torque applied to a steering wheel of the vehicle, the electric assist motor being operatively coupled to the steering means for, when energized, providing steering assist;
• a torque sensor for sensing applied steering torque and for providing an applied steering torque signal indicative thereof;
• control means for monitoring said applied steering torque signal and for providing a torque command signal in response thereto, said electric assist motor being energized in response to said torque demand signal;
• motor commutation sensing means for sensing commutation of said electric assist motor and for providing a signal indicative thereof;
• stall detection means for monitoring said torque command signal and said motor commutation signal and for providing a stall signal in response to said torque command signal and said motor commutation signal;
• over-use detection means for integrating said torque command signal over time and for providing an overuse signal in response to said integrated torque command signal;
• and
• means for providing a fault signal in response to either one said stall signal and said over-use signal.

A method for detecting a fault condition of a motor in an electric assist steering system, comprising the steps of:

• (a) providing a steering means for steering the steerable wheels of a vehicle;
• (b) providing an electric assist motor connected to said steering means for, when energized, providing steering assist;
• (c) sensing the steering torque applied to a steering wheel of said vehicle and providing an applied torque signal indicative thereof;
• (d) monitoring said applied torque signal and providing a torque command signal to said motor in response thereto, said motor being energized in response to said torque command signal;
• (e) sensing commutation of said motor and providing a commutation signal indicative thereof;
• (f) monitoring said torque command signal and said commutation signals;
• (g) providing a stall signal in response to both said torque command signal and said commutation signal.
• (h) integrating said torque command signal;
• (i) providing an over-use signal in response to said integrated torque command signal;
• and
• (j) providing a fault signal in response to either a stall signal or an over-use signal.