Electric power steering apparatus and method of assembling the same

An electric power steering apparatus comprising:

• a steering column having inserted therein a steering shaft to which steering torque is transmitted;
• a reduction gear box coupled to the steering column;
• and
• an electric motor that transmits a steering assisting force to the steering column via a reduction mechanism in the reduction gear box, wherein:
• the electric motor and a control unit including a control board mounted with a control circuit that controls to drive the electric motor are provided side by side in the reduction gear box, and a connection terminal of the electric motor is electrically connected to the control unit directly,
• the reduction gear box includes at least a worm housing unit that houses a worm coupled to an output shaft of the electric motor, a worm-wheel housing unit that houses a worm wheel coupled to the steering shaft, and a torque-sensor housing unit that is coupled to the worm-wheel housing unit to house the torque sensor and coupled to the steering column, and a control-unit mounting section for mounting the control unit is formed in an outer peripheral portion of the worm housing unit, the worm-wheel housing unit, and the torque-sensor housing unit, and
• a distal end of the torque-sensor housing unit is formed as a contraction stopper for the steering column at the time of collapse, and a contraction stopper side end surface position of the control unit mounted on the control-unit mounting section is set further on a worm-wheel housing unit side than the contraction stopper.

An electric power steering apparatus comprising:

• a steering column having inserted therein a steering shaft to which steering torque is transmitted;
• a reduction gear box coupled to the steering column;
• and
• an electric motor that transmits a steering assisting force to the steering column via a reduction mechanism in the reduction gear box, wherein:
• the electric motor and a control unit including a control board mounted with a control circuit that controls to drive the electric motor are provided side by side in the reduction gear box, and a connection terminal of the electric motor is electrically connected to the control unit directly, and
• a motor-side connection section is formed in a position near and opposed to the control unit of the electric motor to project in a direction crossing at least an axial direction, and a unit-side connection section that is in surface contact with the motor-side connection section is formed in a position near and opposed to the electric motor of the control unit.

An electric power steering apparatus comprising:

• a steering column having inserted therein a steering shaft to which steering torque is transmitted;
• a reduction gear box coupled to the steering column;
• and an electric motor that transmits a steering assisting force to the steering shaft via a reduction mechanism in the reduction gear box, characterized in that
• the reduction gear box has installed therein a worm gear mechanism having a worm shaft coupled to an output shaft of the electric motor and a worm wheel meshing with a worm formed in the worm shaft and coupled to the steering shaft, a motor side connection terminal of the electric motor and a control unit side connection terminal of the control unit are formed to overlap in an axial direction near a motor attaching flange formed in the reduction gear box configured to come into surface contact with each other, and the motor side connection terminal and the control unit side connection terminal are brought into surface contact with each other to overlap in the axial direction after coupling of the output shaft of the electric motor and the worm shaft is started.

An electric power steering apparatus comprising:

• a steering column having inserted therein a steering shaft to which steering torque is transmitted;
• a reduction gear box coupled to the steering column;
• and an electric motor that transmits a steering assisting force to the steering shaft via a reduction mechanism in the reduction gear box, characterized in that
• the electric motor and a control unit including a control board mounted with a control circuit that controls to drive the electric motor are provided side by side in the reduction gear box, a motor side connection terminal is formed in a position near the control unit of the electric motor, and a control unit side connection terminal is formed in a position near the electric motor of the control unit,
• at least one of the motor side connection terminal and the control unit side connection terminal is formed in at least one of the electric motor and the control unit with a predetermined dimensional tolerance, whereby the motor side connection terminal and the control unit side connection terminal are opposed to each other with a gap provided between the terminals,
• one of the control unit side connection terminal and the motor side connection terminal is formed in a flexible structure in which the connection terminal is elastically deformed in a direction toward the other of the control unit side connection terminal and the motor side connection terminal to absorb the gap and come into contact with the other connection terminal, and
• the other of the control unit side connection terminal and the motor side connection terminal is formed in a rigid structure in which the connection terminal cannot be deformed toward one of the control unit side connection terminal and the motor side connection terminal.

An electric power steering apparatus comprising:

• a steering column having inserted therein a steering shaft to which steering torque is transmitted;
• a reduction gear box coupled to the steering column;
• and an electric motor that transmits a steering assisting force to the steering shaft via a reduction mechanism in the reduction gear box, characterized in that
• the electric motor and the electric motor control unit are assembled to the reduction gear box, the electric motor includes a brushless motor having an electric contact for external connection connected to a motor coil, the control unit has an electric contact connected to the electric contact of the electric motor, the electric contact of the electric motor and the electric contact of the control unit are arranged in sections where the electric contacts are directly connected in a state in which the electric motor and the control unit are assembled to the reduction gear box, and the control unit is assembled to the reduction gear box to directly transmit heat, which is generated when the electric motor is controlled to be energized, to the reduction gear box.

An electric power steering apparatus assembling method for assembling a steering column having inserted therein a steering shaft to which steering torque is transmitted, a torque sensor that detects the steering torque, an electric motor that transmits a steering assisting force to the steering shaft via a reduction mechanism in a reduction gear box, and a control unit that controls to drive the electric motor on the basis of the steering torque detected by the torque sensor to the reduction gear box, the torque sensor including a torque detection element, the electric power steering apparatus assembling method comprising:

• installing a signal processing circuit that processes a steering torque detection signal detected by the torque detection element in the control unit;
• installing the torque sensor in the reduction gear box;
• subsequently assembling the control unit to the reduction gear box, in which the torque sensor is installed, to electrically connect the torque detection element and the control unit;
• and subsequently assembling the electric motor to the reduction gear box to electrically connect the control unit and the electric motor.