Automatically compressing and friction-driven speed reduction device

An automatically compressing and friction-driven speed reduction device, wherein the device comprises a central shaft (1), a planet wheel (2) comprising a first inclined plane and a second inclined plane, and an inner compression ring (3) and an outer compression ring (4) sleeved outside the planet wheel (2), wherein the inner compression ring (3) comprising a third inclined plane having a same angle with the first inclined plane, a fixing portion and a first connecting portion, and the outer compression ring (4) comprising a fourth inclined plane having a same angle with the second inclined plane and a second connecting portion;

• the central shaft (1) is a cylinder:
• the planet wheel (2) is in a disc shape;
• a planet shaft (6) is installed in a middle portion of the planet wheel (2), and fixed on a housing (8);
• the planet shaft (6) and the planet wheel (2) are provided with a rolling needle (7) therebetween so as to reduce frictional resistance;
• the first connecting portion of the inner compression ring (3) and the second connecting portion of the outer compression ring (4) are provided with multi-fluted threads thereon, and can relatively rotate;
• a tension spring (5) is provide between the fixing portion of the inner compression ring (3), and the first and second connecting portions, so as to preset definite pressures between the inner compression ring (3) and the outer compression ring (4), between the inner compression ring (3) or the outer compression ring (4) and the planet wheel (2), and between the planet wheel (2) and the central shaft (1), wherein the central shaft (1) rotates in a first direction, the planet wheel (2) rotates in a second direction opposite to the first direction and drives the inner compression ring (3) to rotate in second direction because the first inclined plane abuts against the third inclined plane and the outer compression ring (4) to rotate in second direction because the second inclined plane abuts against the fourth inclined plane, and wherein when the outer compression ring (4) is subjected to an increase in dynamic resistance torque, the inner compression ring (3) and the outer compression ring (4) rotate more tightly due to a relative rotating action of the threads, which increases a pressing force on the first and second inclined planes of the planet wheel (2) and the central shaft (1) through the planet wheel (2), so as to raise the friction pressure of the whole friction speed reduction device.