| 摘要 |
PURPOSE: A rack driven power assistance steering system injects balls at the state where an end cap is assembled inside a ball nut and reduces impact and frictional sound during circulation of balls. CONSTITUTION: A rack driven power assistance steering system comprises a rack bar(140), a ball nut(310), an end cap(340), and an end cap ring(330). Outer circumferential threaded grooves(145) are formed on the rack bar. The ball nut comprises inner circumferential threaded grooves(315) corresponding the outer circumferential threaded grooves for coupling with the rack bar by balls. The ball nuts have a ball circulation path(317) in the axial direction between the inner and outer circumferential surfaces thereof. The end cap comprises a ball injection path from the ball circulation path to the inner and the outer circumferential threaded grooves. The end cap is coupled to both inner sides of the ball nut. The end cap ring is coupled to the outside of the end cap and prevents the separation of the balls.
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