Patent ID: 7992461

Claim:
A motion guide apparatus comprising: an elongated shaft including a helical groove formed on an outer peripheral surface thereof, a ball nut movably attached onto said elongated shaft, and including a bore formed therein for receiving said elongated shaft, and including a helical groove formed therein, and including two orifices formed therein and communicative with said helical groove of said ball nut, a ball circulating device including a tubular member engaged with said orifices of said ball nut and including a ball circulating pathway formed in said tubular member and communicative with said helical groove of said ball nut for forming an endless ball guiding passage between said ball nut and said elongated shaft, said tubular member of said ball circulating device including an intermediate segment, two curved segments formed and located at two end portions of said intermediate segment, and two end coupling segments formed and located at an outer portion of said curved segments respectively, and said ball circulating pathway of said tubular member being formed by an intermediate portion, two curved portions, and two end coupling portions, a plurality of ball bearing elements received and engaged with said endless ball guiding passage, and a ball coupler including a flexible coupling member having a plurality of openings formed in said flexible coupling member for receiving and engaging with said ball bearing elements, and wherein said intermediate portion and said curved portions of said ball circulating pathway of said tubular member include an inner diameter (D) no less than a width (W) of said flexible coupling member for allowing said flexible coupling member to be freely moved and rotated relative to said intermediate segment and said curved segments of said tubular member, said tubular member includes a ball guiding channel formed in each of said end coupling segments, and said ball guiding channel of each end coupling segment include a middle section and an inner section, and said inner section of said ball guiding channel of each end coupling segment includes a wider inner end communicative with said curved portion of said curved segment and having a width (T) greater than a width (h) of said middle section of said ball guiding channel of each end coupling segment for circulating and guiding said flexible coupling member to move through said ball guiding channel of each end coupling segment.