Locking structure of tilting and telescopic steering column

A locking structure of a steering column, comprising:

• a main housing that is disposed around a steering shaft and configured to be fixed to a car body;
• an insert pipe that protrudes backward from the main housing;
• a sliding housing that has an arc portion at least substantially surrounding the insert pipe, having a tightening block at each end, and having a variable inner cross-section that changes with changes in distance between the tightening blocks;
• an upper housing that is tiltable relative to the sliding housing;
• a tilt plate that is fixed to the upper housing, extends to a side of the tightening block of the sliding housing, and has an arc-shaped slot corresponding to a rotation distance of the tilt plate relative to the tightening block;
• a locking bolt that passes through the arc-shaped slot of the lilt plate and through the tightening blocks;
• an operation lever that is rotatably fitted on the locking bolt;
• and
• a cam assembly that variably applies a force to the tilt plates and the tightening blocks according to a rotation distance of the operation lever.