US 6,583,594 B2Granted

Electric power steering apparatus

AssigneeMitsubishi Denki Kabushiki Kaisha

InventorsHiroshi Nishimura, Shigeki Ohtagaki

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Abstract

In conventional electric power steering apparatus, a problem exists in that whether or not there is any failure in drive inhibiting means may be erroneously judged, and that it is impossible to judge whether or not a drive inhibition signal is normal. A steering torque detected by a torque sensor and a motor current outputted by motor drive means 5 using a motor drive signal formed by CPU 13 based on the steering torque are inputted to drive inhibiting means 14. The drive inhibiting means 14 outputs a drive inhibition signal and a drive inhibition switch signal based on the relation between the inputted two signals. CPU 13 detects that there is a failure in the drive inhibiting means 14 based on the outputted signals. Upon detecting a failure, a control is conducted so that the motor current is set to 0.

Claims18

Dependent claims

An electric power steering apparatus, comprising:

a motor generating an auxiliary steering force on the basis of a steering torque;
a control means (CPU) for outputting a motor drive signal of a predetermined characteristic corresponding to said steering torque signal and a speed signal of a vehicle;
motor driving means for outputting a motor current applied to said motor corresponding to said motor drive signal;
drive inhibiting means for outputting to said motor a drive inhibition signal to restrict drive of said motor, said drive inhibition signal being determined according to a relation between said steering torque and a motor current;
and
wherein said control means (CPU) detects a failure in said drive inhibiting means according to the relation between said steering torque and the motor current using said drive inhibition signal outputted by said drive inhibiting means.

3 more elements

Dependencies are inferred from the claim text.