Step motor and vehicular indicator instrument

A step motor configured to rotationally drive a rotational body, the step motor comprising:

• a motor main body configured to apply a rotational driving force to the rotational body;
• a motor casing accommodating the motor main body;
• and
• a motor board holding the motor casing, wherein
• the motor board has
• a mounting surface on which the motor main body is mounted via the motor casing,
• a locking surface on an opposite side of the mounting surface, and
• a locking hole penetrating between the mounting surface and the locking surface,
• the motor casing includes
• a locking arm inserted in the locking hole in an elastically deformed state in which the locking arm extends obliquely with respect to the mounting surface and the locking surface, and
• a locking claw having an abutment surface,
• the abutment surface extends obliquely with respect to the mounting surface and the locking surface and locked to the motor board in a state in which the abutment surface is in abutment with a locking corner portion,
• the locking corner portion is formed by the locking surface and a surface of the locking hole in the motor board,
• the step motor further comprising:
• a rotational body illumination light source mounted on the mounting surface and configured to emit a light across the motor main body to illuminate the rotational body, wherein
• the motor casing has a set of the locking arm and the locking claw on each of both sides of the rotational body illumination light source in a reference direction,
• one of the motor casing and the motor board includes positioning protrusions on both sides of the rotational body illumination light source, respectively, in the reference direction,
• the other of the motor casing and the motor board has positioning holes on both sides of the rotational body illumination light source, respectively, in the reference direction to fit with the positioning protrusions and to position the motor casing on the motor board, wherein
• the motor casing further includes dike protrusions which project at a plurality of locations, respectively, around the rotational body illumination light source and is in surface contact with the mounting surface,
• the dike protrusions define gaps therebetween, and
• the positioning protrusions are located in the gaps.

A step motor configured to rotationally drive a rotational body, the step motor comprising:

• a motor main body configured to apply a rotational driving force to the rotational body;
• a motor casing accommodating the motor main body;
• and
• a motor board holding the motor casing, wherein
• the motor board has
• a mounting surface on which the motor main body is mounted via the motor casing,
• a locking surface on an opposite side of the mounting surface, and
• a locking hole penetrating between the mounting surface and the locking surface,
• the motor casing includes
• a locking arm inserted in the locking hole in an elastically deformed state in which the locking arm extends obliquely with respect to the mounting surface and the locking surface, and
• a locking claw having an abutment surface,
• the abutment surface extends obliquely with respect to the mounting surface and the locking surface and locked to the motor board in a state in which the abutment surface is in abutment with a locking corner portion, and
• the locking corner portion is formed by the locking surface and a surface of the locking hole in the motor board,
• the step motor further comprising:
• a rotational body illumination light source mounted on the mounting surface and configured to emit a light across the motor main body to illuminate the rotational body, wherein
• the motor casing further includes dike protrusions which project at a plurality of locations, respectively, around the rotational body illumination light source and is in surface contact with the mounting surface, and
• the dike protrusions define gaps therebetween.

An indicator instrument for a vehicle comprising:

• a step motor configured to rotationally drive a rotational body, the step motor including:
• a motor main body configured to apply a rotational driving force to the rotational body;
• a motor casing accommodating the motor main body;
• and
• a motor board holding the motor casing, wherein
• the motor board has
• a mounting surface on which the motor main body is mounted via the motor casing,
• a locking surface on an opposite side of the mounting surface, and
• a locking hole penetrating between the mounting surface and the locking surface,
• the motor casing includes
• a locking arm inserted in the locking hole in an elastically deformed state in which the locking arm extends obliquely with respect to the mounting surface and the locking surface, and
• a locking claw having an abutment surface,
• the abutment surface extends obliquely with respect to the mounting surface and the locking surface and locked to the motor board in a state in which the abutment surface is in abutment with a locking corner portion, and
• the locking corner portion is formed by the locking surface and a surface of the locking hole in the motor board,
• a rotational indicator configured to indicate a vehicle state value as the rotational body;
• and
• a display member configured to display the vehicle state value, wherein
• the step motor further includes a display illumination light source mounted on the mounting surface and configured to emit a light to illuminate the display member;
• and
• the motor casing further includes a chamfered portion chamfered to form an optical path from the display illumination light source toward the display member.