Torque sensor

A torque sensor for use in an electric power steering apparatus which detects steering torque of a steering wheel and assists a rotation of a steering shaft integrally provided with the steering wheel with a motor, said torque sensor comprising:

• a coil;
• a torque detector for detecting the steering torque based on sampling of transition voltage of coil;
• a control calculator for varying operation timing of the coil and sample holding timing;
• a storage device for storing a plurality of initial values, wherein the coil and the torque detector each have an initial value stored in the storage device;
• and
• means for comparing the initial value in said storage portion with a current value, wherein the current values of at least the coil and the torque detector are compared against their stored initial values respectively when torque detection is not performed, wherein the failure of the torque sensor is detected in accordance with an A/D value obtained by A/D conversion without operating the coil after the sample holding, thereby detecting a failure of the torque sensor.

A torque sensor for detecting torque generated in a rotating shaft, comprising:

• a pair of coils of which impedances are changed in opposite directions in accordance with the torque;
• a pair of electric resistors, each connected in series with one of said pair of coils so as to detect the torque in accordance with transient voltage generated in portions in which said coils and said electric resistors are connected to each other;
• and
• switching means for generating the transient voltage, said switching means being provided for each of the pair of said coils,
• wherein one of said switching means is operated at timing at which the torque is not detected so that a failure of the pair of said coils is detected.

A torque sensor for use in an electric power steering apparatus which detects steering torque of a steering wheel and assists a rotation of a steering shaft integrally provided with the steering wheel with a motor, said torque sensor comprising:

• a pair of coils of which impedances are changed in opposite directions in accordance with the steering torque;
• a pair of electric resistors, each connected in series with one of said pair of coils so as to detect the steering torque in accordance with transient voltage generated in portions in which said coils and said electric resistors are connected to each other;
• and
• switching means for generating the transient voltage, said switching means being provided for each of the pair of said coils,
• wherein one of said switching means is operated at timing at which the steering torque is not detected so that a failure of the pair of said coils is detected.