Power steering system with roller yoke

A power steering system 10 is provided including a rack 14 and at least one yoke element 16 supporting the rack 14. At least one roller element 18 is positioned between the rack 14 and the yoke element 16 to reduce frictional losses as the rack 14 moves over the yoke 16.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Referring now to FIG. 1 , which is an illustration of an embodiment of a power steering system in accordance with the present invention. The power steering 10 includes an input shaft 12 engaged to a rack 14 . Although a single embodiment of the power system 10 is illustrated, it should be understood that a wide variety of power steering systems are known in the prior art and contemplated by this invention. Commonly, rotation of the input shaft effectuates horizontal movement of the rack 14 and thereby controls the steering of the vehicle. Although an input shaft 12 has been illustrated, in alternate systems, such as electric power steering systems, an electric motor or servo may be substituted in place of the input shaft 12 . Referring now to FIG. 2 , which is a cross sectional illustration of an embodiment of a power steering system 10 as shown in FIG. 1 . The power steering system 10 further includes a yoke element 16 . The use of yoke elements 16 in support of the rack 14 is common in the prior art. Commonly, however, yoke elements 16 typically rely on a sliding contact with the rack 14 to allow movement of the rack 14 . This may result in undesirable frictional losses. The present invention further includes a roller element 18 positioned between the yoke element 16 and the rack 14 . The use of the roller element 18 can reduce the frictional losses experienced by the rack 14 as it travels over the yoke 16 and thereby improve the performance of the power steering system 10 . The roller element 18 includes shaft 20 and a rotating cylinder 22 . In an alternate embodiment, the roller may simply be a sphere 24 (see FIG. 3 ). Although two examples of roller elements 18 have been illustrated, it should be understood that a wide variety of roller elements 18 would be obvious to one skilled in the art. The power steering system 10 may further include a guide 26 . The guide 26 , positioned on the rack 14 , is formed to engage the roller element 18 . The use of a guide 26 in combination with roller element 18 helps prevent back roll, a known concern of power steering systems, while continuing to provide the reduced frictional losses associated with the roller element 18 . The guide 26 may be formed in a variety of configurations, however, the preferred configuration of the guide 26 is one that matches the configuration of the roller element 18 . The power steering system 10 may further include a spring element 28 . The spring element 28 is positioned in communication with the yoke element 16 . Spring element 28 helps insure proper contact between the roller element 18 and the rack 14 . Although spring element 28 has been disclosed, it should be understood that it is not required to practice the present invention. Finally, although a single yoke element 16 and roller element 18 have been illustrated, it should be understood that a plurality of yoke elements 16 and roller elements 18 may be utilized to support and control the movement of the rack 14 . In addition, the placement of the yoke elements 16 and the roller elements 18 may be placed in a variety of positions along the rack 14 dictated by the same design considerations presently used for known yoke placement. While the invention has been described in connection with one or more embodiments, it is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of the principles of the invention, numerous modifications may be made to the methods and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.