In general, a steering column is a device which surrounds and rotatably supports a steering shaft for transferring torque, generated by operating a steering wheel by a driver, to a rack-pinion mechanism while being coupled to a vehicle body through a bracket to fix the position of the steering shaft.
The steering column may have a telescopic or tilt function for the convenience of drivers. The tilt function serves to adjust the fixed angle of the steering wheel. The telescopic function allows two hollow pipes to be axially extensible and contractible by inserting the hollow pipes into the steering column, and also serves to absorb impact energy through the collapse of the steering shaft and the steering column in the event of collision of vehicles.
Accordingly, the steering column is classified into a telescopic steering column and a tilt steering column depending on the function thereof. In some cases, a tilt function may also be added to the telescopic steering column. Through such a tilt function, a driver may smoothly operate the steering wheel by adjusting the protruding or tilt angle of the steering wheel so as to be suitable for his/her height or body.
The telescopic or tilt operation of the steering column is typically performed by pressing a housing or releasing the pressing thereof according to tightening or releasing an operating lever.
In particular, the telescopic operation of the steering column is mostly performed by pressing the housing or releasing the pressing thereof.
Representative examples of steering columns are illustrated in FIGS. 1 and 2, and conventional steering columns will be described in brief with reference to FIGS. 1 and 2.
As illustrated in FIG. 1, the steering column according to the related art 1 includes a mounting bracket 10 installed in a vehicle, a housing 20 installed in the mounting bracket 10, and an operating lever 30 for pressing the tilt bracket 10 and the housing 20 or releasing the pressing thereof.
In addition, the housing 20 is formed with a slit 21 for pressing an inner tube 40, and a telescopic guide 22 through which an adjustment bolt 31 of the operating lever 30 slides.
However, in the steering column of the related art 1, the deformation of the housing 20 varies due to the slit 21 and the telescopic guide 22, which may lead to a variation in fixing force of the operating lever 30.
In addition, the adjustment bolt 31 must be moved to the tele-in position (the right in FIG. 1) of the telescopic guide 22 in order to absorb impact energy through the collapse of the steering column in the event of collision of a vehicle. Hence, the steering column has different energy absorption characteristics for each tele-position.
As illustrated in FIG. 2, the steering column according to the related art 2 includes a tilt bracket 10′ installed in a vehicle, a housing 20′ installed in the tilt bracket 10′, an operating lever 30′ for pressing the tilt bracket 10′ and the housing 20′ or releasing the pressing thereof, and an inner tube 40′ inserted into the hollow of the housing 20′.
In addition, the inner tube 40′ is formed with a telescopic guide 41′ through which an adjustment bolt 31′ of the operating lever 30′ slides.
In the steering column of the related art 2, the housing 20′ is fixed, and thus no variation in operating force of the operating lever 30′ occurs.
However, even in the steering column of the related art 2, the adjustment bolt 31′ must be moved to the tele-in position (the right in FIG. 2) of the telescopic guide 41′ in order to absorb impact energy through the collapse of the steering column in the event of collision of a vehicle. Hence, the steering column has different energy absorption characteristics for each tele-position.
Accordingly, it is necessary to develop a steering column having the same energy absorption characteristics for each tele-position while an operating lever has the same operating force for each tele-position.