Electric steering system for automobiles

In combination with an automobile having a front pair of road wheels steerable independently of each other about corresponding ones of a pair of front steering axes of said automobile and a rear pair of road wheels steerable independently of each other about corresponding ones of a pair of rear steering axes of said automobile, a manual steering implement on said automobile, and an electronic control connected to said steering implement operative to convert a manual steering input to said implement into four electric current outputs corresponding to said steering input,

• an electric steering system comprising:
• a front tubular main housing on said automobile aligned on a front transverse axis thereof between said front pair of steerable road wheels,
• a rear tubular main housing on said automobile aligned on a rear transverse axis thereof between said rear pair of steerable road wheels,
• a first steering rack disposed in each of said front and said rear main housings for bodily shiftable movement in opposite directions along the corresponding one of said front and said rear transverse axes and each including an inboard end and an outboard end,
• a second steering rack disposed in each of said front and said rear main housings for bodily shiftable movement in opposite directions along the corresponding one of said front and said rear transverse axes and each including an inboard end and an outboard end,
• means connecting said outboard end of each of said first and said second steering racks to a corresponding one of said front and said rear steerable road wheels so that bodily shiftable movement of each of said first and said second steering racks effects steering pivotal movement of said corresponding steerable road wheel,
• a front pair of reversible electric motors mounted on said front main housing and connected to respective ones of said four electric current outputs whereby each of said front pair of motors is selectively energized by said electronic control independently of the other,
• a rear pair of reversible electric motors mounted on said rear main housing and connected to respective ones of said four electric current outputs whereby each of said rear pair of motors is selectively energized by said electronic control independently of the other,
• a reversible reduction gear train between each of said electric motors of said front and said rear pairs of motors and respective ones of said first and said second steering racks operative when a corresponding one of said electric motors is energized to bodily shift said respective steering rack along a corresponding one of said front and said rear transverse axes and to back drive said corresponding motor when said corresponding motor is deenergized and said respective steering rack is forcibly bodily shifted along said corresponding one of said front and said rear transverse axes,
• means on each of said first steering racks defining a blind bore extending longitudinally from said inboard end thereof to a bottom wall of said bore,
• means on each of said second steering racks defining an outer cylindrical wall adjacent said inboard end projecting into said blind bore in the corresponding one of said first steering racks
• means on each of said second steering racks defining a longitudinally spaced pair of annular shoulders on said outer cylindrical wall each having an outside cylindrical surface slidably engaging said blind bore in a corresponding one of said first steering racks whereby each of said second steering racks is telescopeable relative to said corresponding one of said first steering racks along said front and said rear transverse axes,
• means on said inboard end of each of said second steering racks defining an end wall engageable on said bottom wall of said bore in a corresponding one of said first steering racks to limit relative telescopeable collapse between said first and said second steering racks, and
• a rack nut on each of said first steering racks at an open end of said blind bore therein projecting into an annulus between said blind bore and said outer cylindrical wall of a corresponding one of said second steering racks,
• one of said annular shoulders on each of said second steering racks being engageable on a corresponding one of said rack nuts to limit relative telescopeable extension between said first and said second steering racks.