Magnetic encoder and method of manufacturing magnetic encoder

A method of manufacturing a magnetic encoder for use in a wheel support bearing device of an automobile, wherein

• the magnetic encoder includes:
• an annular support member made of metal;
• and an annular magnet member made of a plastic magnet,
• the annular support member includes:
• a cylindrical portion that fits on an exterior of an inner ring of a bearing of the wheel support bearing device;
• and
• an outward flange portion extending radially outward from an end portion of the cylindrical portion in an inboard side,
• the cylindrical portion has a small-diameter portion press-fitted to the inner ring of the bearing, and a large-diameter portion formed by enlarging a part of the cylindrical portion, the part being closer to the inboard side than the small-diameter portion,
• the annular magnet member is attached to a surface of the outward flange portion in the inboard side,
• the annular magnet member has an inner-diameter side recessed portion formed by depressing, toward an outboard side, a radially inner part in a surface, in the inboard side, of the annular magnet member, and a wraparound portion that wraps around the annular support member toward the outboard side to a stepped portion between the small-diameter portion and the large-diameter portion of the cylindrical portion,
• an inner peripheral surface of the wraparound portion protrudes more radially inward than the inner peripheral surface of the small-diameter portion, the inner peripheral surface of the wraparound portion being press-fitted to the inner ring, and
• a portion of an inner peripheral surface of the inner-diameter side recessed portion lies between the wraparound portion and a gate mark formed in the inner peripheral surface of the inner-diameter side recessed portion,
• the method comprising:
• molding the annular support member by one of (i) pressing and (ii) the pressing and cutting;
• applying a thermosetting adhesive to a part of or an entire of a joint surface of the molded annular support member with the annular magnet member;
• opening an injection molding die and setting, in the injection molding die, the annular support member to which the thermosetting adhesive is applied, as an insert work;
• and
• closing the injection molding die, and injecting a molten resin in a cavity of the injection molding die from an inner-diameter side disk gate of the injection molding die, to thereby mold the annular magnet member, the inner-diameter side disk gate being arranged at a position corresponding to the gate mark of the annular magnet member.