Linear guideway and circulation module thereof

A linear guideway, comprising:

• a guide rail having two opposite rolled grooves;
• a sliding block having a mating trough slidably mounted on the guide rail, the sliding block having four accommodating channels respectively penetrating two opposite portions thereof and respectively arranged at two opposite sides of the mating trough;
• two circulation modules respectively fixed on the opposite portions of the sliding block, each circulation module comprising:
• two circulation tubes respectively coupling through two adjacent accommodating channels, each circulation tube having a straight portion and two U-like cornering portions respectively extended from two opposite ends of the straight portion,
• wherein in each circulation module, the straight portion of each circulation tube is configured to couple through the corresponding accommodating channel, the two cornering portions of each circulation tube are respectively protruding out of two opposite ends of the sliding block, and one of the cornering portions of each circulation tube includes a fill-in opening formed on a portion thereof adjacent to the straight portion;
• two rolling units each having a plurality of rolling pillars, wherein in each circulation tube, the two rolling units are respectively arranged into the two circulation tubes via the fill-in openings;
• and
• two separating sheets,
• wherein in each circulation module, the cornering portion having the fill-in opening of each circulating tube is arranged farther away from the sliding block than the adjacent other cornering portion without the fill-in opening of another the circulating tube, and wherein in each circulation tube, the two separating sheets are respectively installed on the two circulation tubes to shield the fill-in openings;
• two retainers respectively arranged in the two rolled grooves of the guide rail and installed on the sliding block, wherein the retainers are configured to position and keep the positions of the circulation modules with respect to the guide rail;
• and
• two end cap modules fixed on the sliding block and slidably mounted on at the guide rail, and the end cap modules respectively covering the portions of the circulation modules protruding out of the sliding block, wherein part of the rolling pillars of each rolling unit arranged out of the sliding block are spaced apart from the adjacent end cap module by the corresponding circulation tube and the corresponding separating sheet.