Power steering apparatus and method for assembling power steering apparatus

A method for assembling a power steering apparatus, the power steering apparatus comprising:

• a steering mechanism including
• a steering shaft including an input shaft configured to rotate according to a steering operation performed on a steering wheel, and an output shaft connected to the input shaft via a torsion bar and configured in such a manner that a rotation of the input shaft is transmitted to the output shaft, and
• a conversion mechanism configured to convert a rotation of the output shaft into a turning operation of a steering target wheel;
• a housing including
• a first housing including a first opening portion that is open to an opposite side in an axial direction assuming that the axial direction is a direction along a rotational axis of the steering shaft, and one side in the axial direction is an input shaft side corresponding to the input shaft of the steering shaft while the opposite side in the axial direction is an output shaft side corresponding to the output shaft of the steering shaft, and
• a second housing including a second opening portion that is open to the one side in the axial direction so as to close the first opening portion,
• the housing being configured to rotatably support the steering shaft;
• a torque sensor container portion provided in the first housing;
• a connector insertion hole provided in the first housing in a radial direction of the rotational axis, and formed in such a manner that one side in the radial direction is open to the torque sensor container portion while an opposite side in the radial direction is open to an outer circumferential side of the first housing;
• a magnetic member disposed on one of the input shaft side and the output shaft side concentrically with the rotational axis of the steering shaft, and including an N pole and an S pole alternatively arranged in a circumferential direction, assuming that the circumferential direction is a direction around the rotational axis of the steering shaft;
• a first yoke member disposed on the other of the input shaft side and the output shaft side, formed from a magnetic material, located concentrically with the rotational axis of the steering shaft, and including first claw portions that are a plurality of plate members disposed so as to face the magnetic member and a cylindrically formed first cylindrical portion connecting the first claw portions to one another;
• a second yoke disposed on the other of the input shaft side and the output shaft side, formed from a magnetic material, located concentrically with the rotational axis of the steering shaft, including second claw portions that are a plurality of plate members disposed so as to face the magnetic member and a cylindrically formed second cylindrical portion connecting the second claw portions to one another, and arranged in such a manner that the respective second claw portions are alternatively placed between respective claw portions of the first claw portions and the second cylindrical portion is located on an inner circumferential side of the first cylindrical portion while the second cylindrical portion and the first cylindrical portion are spaced apart from each other in the radial direction;
• a first magnetism collection ring overlapping the first cylindrical portion in the axial direction, disposed between the first cylindrical portion and the second cylindrical portion in the radial direction, formed into a circular arc shape from a magnetic material, and configured to generate a magnetic field therein by receiving a magnetic field generated at the first cylindrical portion;
• a second magnetism collection ring overlapping the second cylindrical portion in the axial direction, disposed between the second cylindrical portion and the first magnetism collection ring in the radial direction, formed into a circular arc shape from a magnetic material, and configured to generate a magnetic field therein by receiving a magnetic field generated at the second cylindrical portion;
• a connector;
• a harness provided at the connector and configured to transmit an electric signal to a controller;
• a magnetic sensor serving as a sensor member, disposed in the connector so as to protrude within the torque sensor container portion toward a first opening portion side, including a Hall element configured to detect a change in a magnetic field between the first and second magnetism collection rings that change their respective internal magnetic fields by being affected by magnetic fields of the first and second cylindrical portions that change according to a change in a relative angle between the magnetic member and the first and second claw portions that is caused by a torsion of the torsion bar, and configured to output the change in the magnetic field to the controller as the electric signal;
• and
• an electric motor configured to be driven and controlled based on a motor control signal calculated by the controller based on the change in the magnetic field to provide an operation force to the steering mechanism,
• the method for assembling the power steering apparatus comprising:
• a first step of setting the magnetic sensor into the connector in such a manner that the magnetic sensor and the harness are electrically connected to each other;
• a second step of inserting the connector and the magnetic sensor from an opposite side of the connector insertion hole in the radial direction toward one side of the connector insertion hole in the radial direction, the second step being performed subsequently to the first step;
• and
• a third step of inserting the first magnetism collection ring and the second magnetism collection ring into the torque sensor container portion from the first opening portion in such a manner that the magnetic sensor is situated between the first magnetism collection ring and the second magnetism collection ring in the radial direction, the third step being performed subsequently to the second step.