Cycloid speed reducer

A cycloid speed reducer, comprising:

• an eccentric device comprising a rotating shaft and an eccentric assembly, wherein the eccentric assembly is eccentrically fixed on the rotating shaft and arranged between a first end and a second end of the rotating shaft, wherein as the rotating shaft is rotated, the eccentric assembly is eccentrically rotated relative to an axle center of the rotating shaft;
• a first roller assembly comprising a first wheel disc and plural first rollers, wherein the plural first rollers are disposed on the first wheel disc;
• a second roller assembly comprising a second wheel disc and plural second rollers, wherein the plural second rollers are disposed on the second wheel disc;
• a first rotating disc assembly installed on the eccentric assembly and rotated with the eccentric assembly, and comprising a first cycloid disc and a second cycloid disc, wherein the first cycloid disc is arranged beside the first wheel disc, the first cycloid disc comprises at least one first outer tooth, and the at least one first outer tooth is contacted with the at least one corresponding first roller, wherein the second cycloid disc is arranged beside the first cycloid disc, the second cycloid disc and the first wheel disc are located at two opposite sides of the first cycloid disc, the second cycloid disc comprises at least one second outer tooth, and the at least one second outer tooth is contacted with the at least one corresponding first roller;
• and
• a second rotating disc assembly installed on the eccentric assembly and rotated with the eccentric assembly, and comprising a third cycloid disc and a fourth cycloid disc, wherein the third cycloid disc is arranged between the second cycloid disc and the second wheel disc, the third cycloid disc comprises at least one third outer tooth, and the at least one third outer tooth is contacted with the at least one corresponding second roller, wherein the fourth cycloid disc is arranged between the third cycloid disc and the second wheel disc, the fourth cycloid disc comprises at least one fourth outer tooth, and the at least one fourth outer tooth is contacted with the at least one corresponding second roller.