Rotation transmission device

A rotation transmission device comprising:

• an input shaft;
• an output shaft arranged coaxially with the input shaft;
• a two-way clutch configured to selectively perform and stop transmission of torque between the input shaft and the output shaft;
• and
• an electromagnetic clutch configured to selectively engage and disengage the two-way clutch,
• wherein the two-way clutch comprises:
• an outer ring provided at an end portion of the output shaft;
• an inner ring provided at an end portion of the input shaft;
• a control retainer having first pillars;
• and
• a rotary retainer having second pillars;
• wherein the first and second pillars are arranged between an inner periphery of the outer ring and an outer periphery of the inner ring such that the first pillars circumferentially alternate with the second pillars;
• wherein pockets are defined between adjacent ones of the first and second pillars,
• wherein the two-way clutch further comprises:
• a plurality of pairs of engaging elements, each pair of the engaging elements being received in each of the pockets so as to be engageable with the inner periphery of the outer ring and the outer periphery of the inner ring;
• and
• elastic members each biasing each pair of the engaging elements in a direction away from each other,
• wherein the electromagnetic clutch comprises:
• an armature coupled to the control retainer;
• a rotor axially opposed to the armature;
• and
• an electromagnet axially opposed to the rotor, and configured to attract the armature such that the armature abuts the rotor when the electromagnet is energized,
• wherein the rotation transmission device is configured such that when the electromagnet is energized, the control retainer, together with the armature, is moved in an axial direction toward the rotor, and wherein the rotation transmission device further comprises a motion converting mechanism configured such that when the control retainer is moved in the axial direction, the motion converting mechanism converts the axial movement of the control retainer to a relative rotary motion between the control retainer and the rotary retainer in a direction in which circumferential widths of the respective pockets decrease, thereby disengaging the pairs of engaging elements,
• wherein the rotation transmission device further comprises an anti-rotation arrangement provided between the outer ring and the control retainer and configured to prevent the outer ring and the control retainer from rotating relative to each other with the two-way clutch engaged due to de-energizing of the electromagnet,
• wherein the anti-rotation arrangement comprises:
• a plurality of first protrusions formed on a surface of the outer ring so as to be circumferentially equidistantly spaced apart from each other;
• and
• a plurality of second protrusions formed on a surface of the control retainer axially opposed to the surface of the outer ring so as to be circumferentially equidistantly spaced apart from each other,
• wherein the first protrusions of the outer ring are different in number from the second protrusions of the control retainer such that at least one of the second protrusions can circumferentially engage with at least one of the first protrusions, and
• wherein heat treatment is performed to the first protrusions of the outer ring and the second protrusions of the control retainer.