Control apparatus for motor-driven power steering system in which power suppy to an electric clutch is reduced upon detection of a malfunction

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value in dependence on the vehicle speed detected by said vehicle speed detecting means;
• assist torque determining means for determining assist torque applied by said electric motor;
• load torque arithmetic means for arithmetically determining a load torque on the basis of a steering torque detected by said steering torque detecting means and on the determined assist torque;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operation of said electric motor when said load torque exceeds said abnormal torque decision reference value while decreasing the coupling effort of said coupling effort control means.

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value and a reference time in dependence on the vehicle speed detected by said vehicle speed detecting means;
• load torque arithmetic means for arithmetically determining a load torque on the basis of at least a steering torque detected by said steering torque detecting means;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operating of said electric motor when said load torque exceeds said abnormal torque decision reference value and when in duration in which said load torque exceeds said abnormal torque decision reference value is longer than said reference time, while decreasing the coupling effort of said coupling effort control means.

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value and a reference time in dependence on the vehicle speed detected by said vehicle speed detecting means;
• assist torque determining means for determining assist torque applied by said electric motor;
• load torque arithmetic means for arithmetically determining a load torque on the basis of a steering torque detected by said steering torque detecting means and on the determined assist torque;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operation of said electric motor when said load torque exceeds said abnormal torque decision reference value and when duration in which said load torque exceeds said abnormal torque decision reference value is longer than said reference time while decreasing the coupling effort of said coupling effort control means.

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value in dependence on the vehicle speed detected by said vehicle speed detecting means;
• load torque arithmetic means for arithmetically determining a load torque on the basis of at least a steering torque detected by said steering torque detecting means;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operation of said electric motor when said load torque exceeds said abnormal torque decision reference value while controlling the coupling effort of said coupling effort control means so that the steering torque value detected by said steering torque detecting means does not exceed a predetermined value at which a steering wheel of said motor vehicle can be manipulated by a driver wherein said coupling effort control means comprises an electric clutch and wherein when the coupling effort of said coupling effort control means is decreased, said electric clutch assumes a semi-coupling state.

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value in dependence on the vehicle speed detected by said vehicle speed detecting means;
• assist torque determining means for determining assist torque applied by said electric motor;
• load torque arithmetic means for arithmetically determining a load torque on the basis of a steering torque detected by said steering torque detecting means and on the determined assist torque;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operation of said electric motor when said load torque exceeds said abnormal torque decision reference value while controlling the coupling effort of said coupling effort control means so that the steering torque value detected by said steering torque detecting means does not exceed a predetermined value at which a steering wheel of said motor vehicle can be manipulated by a driver.

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value and a reference time in dependence on the vehicle speed detected by said vehicle speed detecting means;
• load torque arithmetic means for arithmetically determining a load torque on the basis of at least a steering torque detected by said steering torque detecting means;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operation of said electric motor when said load torque exceeds said abnormal torque decision reference value and when duration in which said load torque exceeds said abnormal torque decision reference value is longer than said reference time while controlling the coupling effort of said coupling effort control means so that the steering torque value detected by said steering torque detecting means does not exceed a predetermined value at which a steering wheel of said motor vehicle can be manipulated by a driver.

In a motor-driven power steering system for a motor vehicle which includes vehicle speed detecting means for detecting a speed of said motor vehicle, steering torque detecting means for detecting a steering torque applied to a steering mechanism of said motor vehicle, and an electric motor operatively coupled to said steering mechanism through the medium of coupling effort control means, wherein an assist torque is applied to said steering mechanism by driving said electric motor,

• an apparatus for controlling said motor-driven power steering system, comprising:
• abnormal torque decision reference value arithmetic means for determining an abnormal torque decision reference value in dependence on the vehicle speed detected by said vehicle speed detecting means;
• assist torque determining means for determining assist torque applied by said electric motor;
• load torque arithmetic means for arithmetically determining a load torque on the basis of at least a steering torque detected by said steering torque detecting means and on the determined assist torque;
• torque comparison means for comparing said load torque with said abnormal torque decision reference value;
• and
• motor fault monitor/control means for stopping operation of said electric motor when said load torque exceeds said abnormal torque decision reference value and when duration in which said load torque exceeds said abnormal torque decision reference value is longer than said decision reference time while controlling the coupling effort of said coupling effort control means so that the steering torque value detected by said steering torque detecting means does not exceed a predetermined value at which a steering wheel of said motor vehicle can be manipulated by a driver.