Constant-velocity joint

A constant-velocity rotary joint for torque transmission comprising:

• an outer joint portion comprising a plurality of outer ball tracks;
• an inner joint portion comprising a plurality of inner ball tracks;
• balls configured to transmit torque, each of the ball being guided in a track pair formed by one of the plurality of outer ball tracks and one of the plurality of inner ball tracks;
• and
• a cage comprising cage windows which are configured to accommodate and to retain the balls in a common joint center plane when the constant-velocity rotary joint is straight,
• wherein,
• each of the plurality of outer ball tracks comprise an outer ball track center line and a track base line which extends equidistantly to the outer ball track center line,
• each of the plurality of inner ball tracks comprise an inner ball track center line and a track base line which extends equidistantly to the inner ball track center line,
• the outer joint portion further comprises a longitudinal axis, an opening, and a connecting part, the opening and the connecting part being arranged axially opposite to each other,
• each outer ball track center line comprises at least one concavely curved inner portion and an outer portion arranged opposite thereto, the outer portion being configured to widen in a direction towards the opening of the outer joint portion and with respect to the longitudinal axis of the outer joint portion,
• each inner ball track center line comprises at least one convexly curved outer portion and an inner portion arranged opposite thereto, the inner portion being configured to widen in a direction towards the connecting part of the outer joint portion and with respect to the longitudinal axis of the outer joint portion,
• when the constant-velocity rotary joint is maximally deflected, one of the balls contacts the outer portion of one of the plurality of outer ball tracks and the inner portion of one of the plurality of inner ball tracks, and
• when the constant-velocity rotary joint is straight,
• the inner ball track center line and the outer ball track center line of the track pair intersect in an intersection point and are not mirror-symmetrical with respect to a mirror plane through the intersection point, the mirror plane being arranged in the joint center plane or parallel thereto, and
• the inner portion of the inner ball track center line widens more, with respect to the longitudinal axis of the outer joint portion, than the outer portion of the outer ball track center line.