Electric steering apparatus

An electric steering apparatus comprising:

• a lower column fixed to a vehicle body and having a housing provided thereon;
• an upper column telescopically connected 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 movement with said upper column relative to said lower column and having a first end connected to a steering wheel and a second end connected to said second end of said lower shaft such that the connected second ends may move axially but not rotatably relative to each other;
• a screw shaft having a non-threaded first end portion connected to 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 supporting said nut means in such a manner as to prevent said nut means from moving in an axial direction of said lower column but to permit said nut means to rotate relative to said screw shaft, said screw shaft thus moving in the axial direction of said lower column upon rotation of said nut means by said motor;
• first back-lash eliminating means for eliminating back-lash by pressing an outer surface of said screw shaft so that said screw thread of said screw shaft presses against said threaded portion of said nut means;
• and
• second back-lash eliminating means for eliminating back-lash by pressing said antifriction bearing means so that each said inner race presses against a corresponding said outer race through an associated one of said groups of rolling members.

An electric steering apparatus comprising:

• a lower column fixed to a vehicle body;
• 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 movement 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 supporting said nut means for rotating relative to said screw thread and in such a manner 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 being movable in the axial direction of said lower column upon rotation of said nut means by said electric motor while pivoting relative to said screw shaft pivot portion;
• aligning means for aligning a rotational axis of said nut means with the axis of said screw shaft during movement of said screw shaft;
• and
• pressing means for pressing said antifriction bearing means to eliminate back-lash.