Electric linear drive, in particular for adjusting furniture used for sitting or lying down

An electric motor-actuated linear drive for adjusting moveable parts, the drive comprising:

• a drive motor, a threaded spindle, a speed reduction gear arranged between the drive motor and the threaded spindle, a spindle nut being carried on the threaded spindle, being selectively arrestable in a direction of rotation, and being displaceable in an axial direction of the threaded spindle in dependence on the direction of rotation of the threaded spindle, and a stroke element drivable by axial movement of the spindle nut for adjusting the moveable parts, wherein a drive wheel of the speed reduction gear is fixedly connected to the threaded spindle,
• wherein the stroke element is guided non-rotatably with respect to its longitudinal axis in the axial direction of the threaded spindle,
• wherein the spindle nut is coupleable to the non-rotatably guided stroke element, such that the spindle nut is selectively connectable non-rotatably thereto or is releasable therefrom,
• wherein a wrap spring couples the stroke element with the spindle nut,
• wherein the spindle nut has a cylindrical outside periphery on which the wrap spring is arranged;
• the electric motor-actuated linear drive further comprising a sleeve between an outside periphery of the spindle nut and the wrap spring, the sleeve being arranged non-rotatably on the spindle nut and comprising a material of high strength and with good friction properties, and an actuating ring arranged in a rotatably but axially non-displaceable manner on the outside periphery of the spindle nut or on the sleeve, the actuating ring being connected to an end of the wrap spring remote from the stroke element and having an actuating element for rotation of the actuating ring in an opening direction of the wrap spring,
• wherein the actuating element of the actuating ring has a form of a radially projecting nose,
• wherein an actuating bar is arranged parallel to the threaded spindle along a path of displacement of the spindle nut,
• wherein the actuating bar bears against the radially projecting nose and is moveable in a tangential direction relative to the actuating ring to rotate the actuating ring and thereby open the wrap spring, and
• wherein the actuating bar comprises a plurality of inclined surfaces arranged displaced in the axial direction and cooperating with corresponding counterpart surfaces on a housing.