Electric power steering device

An electric power steering device comprising:

• an electric motor;
• a rack shaft configured to move in an axial direction;
• a conversion unit configured to convert rotational driving force of the electric motor into movement of the rack shaft;
• a first housing configured to cover a part of an outer surface of the rack shaft, the first housing including a first fixed portion configured to be fixed to a vehicle;
• a second housing configured to cover a part of the outer surface of the rack shaft, the second housing including a cover portion configured to cover the conversion unit, the second housing including a second fixed portion configured to be fixed to the vehicle;
• and
• a third housing disposed between the first housing and the second housing and configured to cover a part of the outer surface of the rack shaft, the third housing including a support portion configured to support the electric motor, wherein
• the support portion includes a motor mounting surface on which the electric motor is mounted via a plurality of bolts, said support portion having a plurality of through-holes into which the plurality of bolts are inserted,
• the third housing constitutes a housing unit jointly with the electric motor supported by the support portion and with the conversion unit including a driving pulley attached to an output shaft of the electric motor, a driven pulley attached to the rack shaft, and a belt stretched between the driving pulley and the driven pulley,
• the third housing includes, at a side thereof close to one end of the rack shaft, a second connecting portion configured to change a position thereof relative to a first connecting portion of the first housing, and the third housing is configured to support the electric motor and the conversion unit at a side thereof close to the other end of the rack shaft,
• an O-ring is fitted between the first connecting portion and the second connecting portion,
• the third housing includes a third connecting portion,
• the second housing includes a fourth connecting portion, and
• another O-ring is fitted between the third connecting portion and the fourth connecting portion.

An electric power steering device comprising:

• an electric motor;
• a rack shaft configured to move in an axial direction;
• a conversion unit configured to convert rotational driving force of the electric motor into movement of the rack shaft;
• a first housing configured to cover a part of an outer surface of the rack shaft, the first housing including a first fixed portion configured to be fixed to a vehicle;
• a second housing configured to cover a part of the outer surface of the rack shaft, the second housing including a cover portion configured to cover the conversion unit, the second housing including a second fixed portion configured to be fixed to the vehicle;
• and
• a third housing disposed between the first housing and the second housing and configured to cover a part of the outer surface of the rack shaft, the third housing including a support portion configured to support the electric motor, wherein
• the support portion includes a motor mounting surface on which the electric motor is mounted via a plurality of bolts, said support portion having a plurality of through-holes into which the plurality of bolts are inserted,
• an O-ring is fitted at a connecting portion between the first housing and the third housing,
• another O-ring is fitted at a connecting portion between the second housing and the third housing, and
• the third housing constitutes a housing unit jointly with the electric motor supported by the support portion and with the conversion unit including a driving pulley attached to an output shaft of the electric motor, a driven pulley attached to the rack shaft, and a belt stretched between the driving pulley and the driven pulley.