CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2019-0072104, filed Jun. 18, 2019, the entire contents of which is incorporated herein for all purposes by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to an electric steering column device for a vehicle capable of improving steering performance.

2. Description of the Related Art

In general, a vehicle is driven by transferring a force to a road surface with tires interposed therebetween, which is configured to be controlled by moving front wheels or rear wheels through a steering device operated by a driver on a driver's seat.

Since large power is used in order to rotate a steering wheel used as such a steering device, large power is required in order to operate the steering wheel with force of a person. Therefore, a power steering system uses forces of an electric motor and a hydraulic pressure as auxiliary power.

The disclosure of this section is to provide background of the invention. Applicant notes that this section may contain information available before this application. However, by providing this section, Applicant does not admit that any information contained in this section constitutes prior art.

SUMMARY

Aspects of the present disclosure provide an electric steering column device for a vehicle capable of securing optimized steering performance by adjusting steering responsibility of a steering wheel depending on a driving state of the vehicle.

According to an embodiment of the present disclosure, an electric steering column device for a vehicle includes: a first shaft and a second shaft provided in a column housing and transferring a torque of a steering wheel to a gear box; a variable shaft provided in the column housing so as to be movable in an axial direction of the first shaft and the second shaft and connected to the first shaft and the second shaft so as to rotate together with the first shaft and the second shaft, the first shaft being connected to the variable shaft so that the first shaft always rotates at the same rotation speed as that of the variable shaft and the second shaft being connected to the variable shaft so that a rotation speed of the second shaft is varied as compared with the first shaft depending on whether or not the variable shaft moves in the axial direction; and a driving module installed on the column housing and transferring power to the variable shaft to allow the variable shaft to move in the axial direction.

The first shaft may be connected to one end portion of the variable shaft in a spline structure, and the second shaft may be connected to the other end portion of the variable shaft in a screw structure.

A first hole into which an insertion end portion of the first shaft is inserted may be formed in one end portion of the variable shaft, and spline gears extending in a straight line shape in the axial direction may be formed on an outer peripheral surface of the insertion end portion of the first shaft and an inner peripheral surface of the first hole so as to be matched to each other.

A second hole into which an insertion end portion of the second shaft is inserted may be formed in the other end portion of the variable shaft, and screw gears extending in a spiral shape in the axial direction may be formed on an outer peripheral surface of the insertion end portion of the second shaft and an inner peripheral surface of the second hole so as to be matched to each other.

The first shaft and the second shaft may be installed in the column housing so as to be rotatable through a first bearing and a second bearing, respectively.

The variable shaft may be installed in the column housing so as to be rotatable through a third bearing, and the third bearing may be installed in the column housing so as to be movable in the axial direction and be connected to the driving module and receive the power from the driving module to move.

The driving module may include: an electric motor fixedly installed in the column housing and including a pinion rotating at the time of transferring the power; and a rack bar coupled to the third bearing and gear-connected to the pinion to linearly move in the axial direction at the time of the rotation of the pinion.

The electric steering column device for a vehicle may further include a controller receiving driving information of the vehicle and controlling the driving module based on the driving information of the vehicle to control a moving direction of the variable shaft, thereby allowing a steering response speed to be changed due to the variation in the rotation speed of the second shaft.

Aspects of the invention provide an electric steering column device for a vehicle, comprising: a column housing; a first shaft, an intermediate or connection shaft and a second shaft provided in a column housing, and aligned along an axis in order; the intermediate shaft disposed between and interconnecting the first and second shafts, wherein the first, intermediate and second shafts are rotatable together about an axis; the first shaft connected to the steering wheel and the second shaft connected to the gear box such that the shafts transfer a torque of the steering wheel to the gear box; the intermediate shaft being movable in an axial direction with respect to the first shaft and the second shaft; the first shaft being connected to the intermediate shaft, wherein the first shaft always rotates at the same rotation speed as that of the intermediate shaft; the second shaft being connected to the intermediate shaft, wherein a rotation speed of the second shaft is varied as compared with the first shaft depending on the relative location of the intermediate shaft to the second shaft; and a driving module installed on the column housing and transferring power to the intermediate shaft to allow the intermediate shaft to move in the axial direction.

