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Electric steering apparatus

  • US 4,967,618 A
  • Filed: 10/24/1989
  • Issued: 11/06/1990
  • Est. Priority Date: 04/17/1987
  • Status: Expired
First Claim
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1. An electric steering apparatus comprising:

  • a lower column fixed to a vehicle body and having a housing provided thereon;

    an upper column having a tilting pivot portion and a screw shaft pivot portion, said upper column being pivotally attached to said lower column at said tilting pivot portion so as to be tiltable with respect to said lower column;

    a lower shaft rotatably received in said lower column and having a first end and a second end, said first end being connected to a steering gear;

    an upper shaft rotatably received in said upper column for tilting with said upper column and having a first end connected to a steering wheel and a second end connected to said second end of said lower shaft through a universal joint such that an angle formed between respective axes of said upper and lower shafts may be changed by tilting of said upper shaft with said upper column;

    a screw shaft having a non-threaded first end portion pivotally connected directly to said screw shaft pivot portion of said upper column, and a second end portion formed with a screw thread;

    nut means rotatable by an electric motor and having a threaded portion engaged with said screw thread of said screw shaft;

    antifriction bearing means mounted in said housing and comprising two inner races provided on a surface of said nut means, two outer races fitted in said housing, and two groups of rolling members provided between said inner races and said outer races, said antifriction bearing means being mounted in said housing in such a manner as to support said nut means for rotation relative to said screw thread and as to prevent said nut means from moving in an axial direction of said lower column and from moving in a direction perpendicular to said lower column, said screw shaft thus moving in the axial direction of said lower column upon rotation of said nut means by said motor while pivoting relative to said screw shaft pivot portion;

    aligning means for aligning a rotational axis of said nut means with an axis of said screw shaft during said pivoting of said screw shaft; and

    back-lack eliminating means for eliminating back-lash by pressing on an outer surface of said screw shaft such that said screw thread presses against said threaded portion of said nut means.

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