Ball spline with oil injection structure

A ball spline with an oil injection structure comprises a spline shaft, a spline sleeve and a linear bearing unit. The spline shaft is provided with a plurality of pairs of first ball grooves, the spline sleeve can slide and sleeve the spline shaft, and the spline sleeve is provided with a plurality of pairs of second ball grooves opposite to the first ball grooves, an outer ring groove concavelyformed in the inner ring face and an oil injection hole communicating with the outer ring groove from the outer ring face. The linear bearing unit is installed between the spline shaft and the splinesleeve and provided with a retainer and a plurality of ball sets, the retainer is provided with a plurality of circulation channels, each circulation channel and the corresponding pair of second ballgrooves form a circulation path, the retainer is further provided with an inner ring groove and a plurality of grooves communicating with the corresponding circulation paths, and the outer ring grooveand the inner ring groove j