A reverse input blocking clutch has a pressed member having a pressed surface on the inner circumferential surface; an input member having an input-side engaging portion arranged on the inner side in the radial direction of the pressed surface and coaxially arranged with the pressed surface; an output member having an output-side engaging portion arranged further on the inner side in the radial direction than the input-side engaging portion and coaxially arranged with the pressed surface; an engaging element arranged on the inner side in the radial direction of the pressed surface so as to move in a first direction which is a far-near direction with respect to the pressed surface; and an elastic member arranged at a position overlapping the output-side engaging portion with respect to the first direction so as to be elastically stretched between the output-side engaging portion and the engaging element.

A torque transmission mechanism transmits a torque produced by a rotation of a driving shaft to an output shaft. A clutch mechanism is provided between a motor and the torque transmission mechanism. The torque transmission mechanism includes a magnet coupling including a driving magnet member coupled to the driving shaft side and a driven magnet member coupled to the output shaft side. The driving magnet member and the driven magnet member are arranged such that magnetic surfaces on each of which S-pole magnets and N-pole magnets are alternately arranged face other. The clutch mechanism transmits the torque produced by the rotation of the driving shaft to the driving magnet member but does not transmit a torque the driving magnet member receives from the driven magnet member to the driving shaft.

A torque transmission mechanism transmits a torque produced by a rotation of a driving shaft to an output shaft. A clutch mechanism is provided between a motor and the torque transmission mechanism. The torque transmission mechanism includes a magnet coupling including a driving magnet member coupled to the driving shaft side and a driven magnet member coupled to the output shaft side. The driving magnet member and the driven magnet member are arranged such that magnetic surfaces on each of which S-pole magnets and N-pole magnets are alternately arranged face other. The clutch mechanism transmits the torque produced by the rotation of the driving shaft to the driving magnet member but does not transmit a torque the driving magnet member receives from the driven magnet member to the driving shaft.

[Problem] To realize a reverse input blocking clutch capable of suppressing looseness of an output member.

[Solution] The reverse input blocking clutch has a pressed member having a pressed surface 20 on the inner circumferential surface; an input member that has an input-side engaging portion 8 arranged on the inner side in the radial direction of the pressed surface 20, and is coaxially arranged with the pressed surface 20; an output member that has an output-side engaging portion 11 arranged further on the inner side in the radial direction than the input-side engaging portion 8 on the inner side in the radial direction of the pressed surface 20, and is coaxially arranged with the pressed surface 20; an engaging element 5 arranged on the inner side in the radial direction of the pressed surface 20 so as to be able to move in a first direction which is a far-near direction with respect to the pressed surface 20; and an elastic member 56 arranged at a position overlapping the output-side engaging portion 11 with respect to the first direction so as to be elastically stretched between the output-side engaging portion 11 and the engaging element 5.

The rotation transmission state switching device comprises a clutch device comprising a first rotating member having a first-rotating-member-side engaging portion, a second rotating member having a second-rotating-member-side engaging portion, a third rotating member having a third-rotating-member-side engaging portion; and an engaging element having an engaging-element-side first engaging portion engaging with the first-rotating-member-side engaging portion, an engaging-element-side second engaging portion engaging with the second-rotating-member-side engaging portion, and an engaging-element-side third engaging portion engaging with the third-rotating-member-side engaging portion; and a restriction device configured to switch between allowing and restricting rotation of the first rotating member, allowing or preventing torque transmission between the second rotating member and the third rotating member.

The rotation transmission state switching device comprises a clutch device comprising a first rotating member having a first-rotating-member-side engaging portion, a second rotating member having a second-rotating-member-side engaging portion, a third rotating member having a third-rotating-member-side engaging portion; and an engaging element having an engaging-element-side first engaging portion engaging with the first-rotating-member-side engaging portion, an engaging-element-side second engaging portion engaging with the second-rotating-member-side engaging portion, and an engaging-element-side third engaging portion engaging with the third-rotating-member-side engaging portion; and a restriction device configured to switch between allowing and restricting rotation of the first rotating member, allowing or preventing torque transmission between the second rotating member and the third rotating member.

A brake-side clutch part includes an outer ring whose rotation is restricted and an output shaft from which rotation is output. The outer ring is provided with a slide gear that meshes with the output shaft when rotational torque is cut off and releases a meshing state with the output shaft when rotational torque is transmitted. The output shaft is provided with an inner gear that meshes with the slide gear so as to be slightly rotatable. An alignment part that aligns a phase of the inner gear with that of the slide gear when rotational torque is cut off, and a centering part that returns the inner gear to a neutral position with respect to the output shaft when rotational torque is transmitted are provided between the inner gear and the output shaft.

A non-return device for coaxial rotation transmission includes coaxial input and output shafts, a frame for guiding the rotation of the shafts. A locking element is urged in radial translation through a channel of the output shaft between a radial locking position, in which the locking element projects from the channel so as to prevent a rotation of the output shaft by abutting against the frame, and a radial unlocking position, in which the locking element is retracted so as to allow axial rotation of the output shaft. The input shaft includes means for radially switching the locking element between the locking and unlocking positions thereof.

A non-return device for coaxial rotation transmission includes coaxial input and output shafts, a frame for guiding the rotation of the shafts. A locking element is urged in radial translation through a channel of the output shaft between a radial locking position, in which the locking element projects from the channel so as to prevent a rotation of the output shaft by abutting against the frame, and a radial unlocking position, in which the locking element is retracted so as to allow axial rotation of the output shaft. The input shaft includes means for radially switching the locking element between the locking and unlocking positions thereof.

The invention relates to a refinement of a spindle drive (1), and to a louvered window or a louvered shutter having a spindle drive for moving louver elements such that applied return forces and return torques can be absorbed better, and in particular without placing a load on the drive motor. For this purpose, the spindle drive (1) has a specially designed return stop mechanism (6) arranged between a drive shaft of a drive motor (3) and a threaded spindle (4).