An electric power steering apparatus for assisting the steering force of a steering
member by an electric motor (18) driven by a driving circuit (13)
connected to a power supply (P) by power connecting means (15a).
The electric power steering apparatus comprising: means (12) for detecting
a short-circuit failure on the driving circuit (13) and on a wiring connecting
the driving circuit (13) and the electric motor (18); power off means
(15) for turning off the power connecting means (15a) when
a short circuit failure is detected; current detecting means (17) for detecting
the value of a current flowing between the electric motor (18) and the driving
circuit (13) after the power off means (15) turns off the power connecting
means (15a); and current cutting means (Fa, Fb) for, when the current
detecting means (17) detects a current value exceeding a predetermined value,
irreversibly cutting off the current whose current value exceeds the predetermined.
With such a configuration, it is possible to realize an electric power steering
apparatus that has simple structures to enable a reduction in the cost of parts,
and prevents the force required for steering from becoming too large at occurring
of a short-circuit failure.
