Tensioning and damping element for endless chain drive, especially for roller chain drives

A tensioning and damping element, wherein

• the tensioning and damping element is disposable between a tight side and a slack side of an endless chain drive and thereby acting constantly on both sides of the endless chain drive,
• the tensioning and damping element being formed as an elastically deformable element which includes elastic plastic, and comprising:
• a ring part,
• at the outer periphery of the ring part, a corresponding toothed rim, capable of gripping the endless chain drive,
• elastically deformable, laterally open teeth and,
• in a root circle of the toothed rim, radially elastic roller-seatings between the teeth, which pass into the ring part,
• and wherein the tensioning and damping element is deformable between a shape of a concentric element and a shape of a Cassinian curve with a shape close to an ellipse, the diameter of a pitch circle or a smallest axis of the tensioning and damping element being larger than a diameter of a pitch circle of a smallest chain sprocket of the endless chain drive,
• wherein the radially elastic roller-seatings have bulges, which are axially on opposite sides in the width of the radially elastic roller-seatings, arranged on either side of the ring part and lying externally on a root circle with a roller-seating depression of a depth e0=0.5(Df−Dv), Df being the diameter of the root circle and Dv being the diameter of a depression circle, the roller-seating depression extends centrally between the bulges in the ring part between the root circle and the depression circle, the amount e0 of which, in a stress-free starting position, is larger than the amount of a height h1 in a camber in an elliptical, pretensioned state,
• wherein the toothed rim has grooves between the ring part and the bulges, and wherein the toothed rim has an extended pitch q0 with 1.02×p0<q0<1.08×p0, p0 being a pitch of the endless roller chain, which is not worn out,
• wherein the radially elastic roller-seatings are extended with a profile shape similar to a semi-elliptical curve, which lies radially on the root circle and which has a main apex axis between two points which, projected on the pitch circle, has a length l0, which is given by 1.1×d1<l0<1.45×d1, wherein d1 is a diameter of a roller of the endless roller chain.