Spindle drive having a reverse-lock transmission

A spindle drive, in particular for the motor-driven movement of louver elements of louvered windows or louvered shutters, said spindle drive comprising:

• a threaded spindle that is driven in a rotary manner by a drive motor;
• and
• a spindle nut which is in engagement with the threaded spindle and which is displaceable axially along the threaded spindle by rotating the threaded spindle;
• a return stop mechanism arranged between a drive shaft of the drive motor and the threaded spindle, wherein the return stop mechanism includes:
• a drive element;
• and
• an output element;
• wherein the drive element and the output element are arranged concentric to a rotational axis and are rotatable about this rotational axis relative to each other by an angular range within a guide surrounding one of the drive element and the output element, which guide has an internal surface having a circular cross-section which is located in a section plane perpendicular to the rotational axis, and which guide is also arranged concentrically to the rotational axis;
• wherein at least one radially protruding driving protrusion is provided at a first of the drive element and the output element;
• wherein a driving slot is provided in a second of the drive element and the output element;
• wherein the driving protrusion protrudes into the driving slot;
• wherein the driving slot, as seen in a circumferential direction relative to the rotational axis, has a slot width which is greater by a first value than a width of the driving protrusion in the circumferential direction;
• wherein at least one notch is provided in the first of the drive element and the output element having the driving protrusion, in which notch at least one rolling element is arranged in a position in the notch between an inner surface of the guide and a surface of the second of the drive element and the output element having the driving slot;
• wherein the first of the drive element and the output element having the driving protrusion has an extension of a second value, as measured from the driving protrusion to an edge of the notch facing the driving protrusion along the circumferential direction;
• wherein the surface of the second of the drive element and the output element having the driving slot, in a region covered by the notch in a middle section in a plane transverse to the rotational axis, extends in the shape of a circular section concentrical to the extension of the inner surface of the guide, and in this region has a constant first distance to the inner surface of the guide, and
• wherein the surface of the second of the drive element and the output element having the driving slot has outer sections in the region covered by the notch, which outer sections are positioned on respective sides of the middle section as seen in the circumferential direction, in which the surface of the second of the drive element and the output element having the driving slot deviates from the circular extension and has a second distance to the inner surface of the guide, which is less than the first distance;
• wherein the rolling elements have a roller diameter which is smaller than or the same size as the first distance, but larger than the second distance;
• and
• wherein the second value is selected such that the first of the drive element and the output element having the driving protrusion covers the outer section located adjacent to a side surface of the driving slot, which faces the edge of the notch, when the driving protrusion comes to a stop against said side surface.