Locking mechanism for a telescopic steering wheel

A locking mechanism for a telescopic steering wheel which includes a housing, an outer cylinder rotatably supported within the housing, a locking member slidably mounted within the outer cylinder, a steering shaft movably mounted within the outer cylinder, engaged with the locking member and operatively connected to the steering wheel, a locking rod rotatably mounted in the steering shaft and engaged with the locking member for attaining a locked or unlocked position of the locking member, a telescopic lever connected to the locking rod and movable between the locked and unlocked position and a mechanism for continuously urging the telescopic lever into the locked position.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a locking mechanism, and more particularly 
to a locking mechanism for a telescopic steering wheel. 
2. Description of the Prior Art 
In a conventional locking mechanism for a telescopic steering wheel, the 
forward and rearward moving function of the steering wheel is performed 
such that a telescopic lever is first actuated by releasing operation for 
releasing the locked state and a telescopic lever is manually actuated in 
a direction opposite to the releasing operation upon locking operation, 
namely the telescopic lever is locked by a manual tightening force. 
Accordingly, it is possible that the tightening force for the locking 
mechanism is insufficient and it is therefore possible that driving 
function is lost due to a sudden release of the locking mechanism. 
Moreover, if the tightening force for the locking mechanism is excessive, 
the locking mechanism will be damaged. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an improved locking 
mechanism for a telescopic steering wheel which obviates the 
aforementioned drawbacks of the described conventional locking mechanism. 
A further object of the present invention is to provide an improved locking 
mechanism for a telescopic steering wheel which can be reliably adjusted 
and locked in position. 
A still further object of this invention is to provide an improved locking 
mechanism for a telescopic steering wheel which is relatively simple in 
construction and accordingly includes a minimum number of parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIGS. 1-3 and 10, a steering wheel 1 is shown which can be 
expanded and contracted, that is, the steering wheel 1 is shifted forward 
and rearward so as to be expanded and contracted according to a physique 
of the driver and is locked at a suitable position. For attaining the 
function a steering shaft 2 fixed to the steering wheel 1 is forwardly or 
rearwardly movably mounted within an outer cylinder 5 which, in turn, is 
rotatably supported by a bearing 4 within a housing 3 and thereafter the 
outer cylinder 5 and the steering shaft 2 are locked together by a locking 
member 6. 
The locking member 6 is engaged with the steering shaft 2 by means of a 
tapered portion thereof and is also engaged with a screw portion of a 
pointed end of a locking rod 8 rotatably inserted within steering shaft 2. 
The locking rod 8 is engaged with the steering shaft 2 through a screw 7 
thereof. The locking member 6 is slidable in the direction of the steering 
wheel 1 according to the rotation of the locking rod 3 and the outer 
diameter of the locking member 6 is engaged with tapered portions of the 
steering shaft 2 and the locking member 6. Accordingly, the locking member 
6 is operatively positioned on an inner cylindrical surface portion of the 
outer cylinder 5 and is locked so as to integrally rotate the steering 
shaft 2 and the outer cylinder 5. 
Reference numeral 9 denotes a telescopic lever fixed to the locking rod 8. 
The housing 3 is enclosed within a column cover 10. Reference numeral 11 
denotes a tilt lever for attaining the desired tilting position of the 
steering wheel 1. Reference numeral 12 indicates a dash board, 13 a 
bracket, 14 a column tube, 15 a joint member, 16 a joint shaft, 17 a 
toothed portion, and 18 an intermediate shaft. 
The telescopic lever 9 is slidable between a locked position A shown by a 
solid line and an unlocked position B shown by a chain and dotted line in 
FIGS. 2, 4. As viewed from FIG. 6, the telescopic lever 9 is engaged with 
a recessed portion 19 of a main body of the steering wheel 1 for 
maintaining the unlocked position B. The main body 1a of the steering 
wheel 1 is provided with a tapered portion 20 which is inclined in the 
direction of the locked position A for obtaining smooth movement of the 
telescopic lever 9. An intermediate portion of the telescopic lever 9 is 
connected to the locking rod 8 within the main body 1a of the steering 
wheel 1. One end of a spring 21, the other end of which is attached to the 
main body 1a of the steering wheel 1, is operatively connected to an end 
portion 9a of the telescopic lever 9. 
The telescopic lever 9 is movable against the biasing force of the spring 
21 upon movement in the direction of the unlocked position B and is 
automatically rotatably moved due to the urging force of the spring 21 
upon movement into the locked position A. The telescopic lever 9 is 
engaged with a recessed portion 19 during the state of the unlocked 
position B for maintaining such position. When the steering wheel 1 is 
adjusted in the unlocked state, the telescopic lever 9 is prevented due to 
the urging force of the spring 21 from automatic movement into the locked 
position A, so that the adjusting operation is simplified. 
In the situation where the telescopic lever 9 is released from the recessed 
portion 19 by moving the lever 9 after movement of the steering wheel 1 
into the desired position, the telescopic lever 9 is automatically moved 
into the locked position A due to the urging force of the spring 21, so 
that the steering shaft 2 is locked to the outer cylinder 5 by a 
predetermined locking force. 
In FIGS. 7, 8, 9, a plate spring 22 is fixed nearly on a central portion of 
the telescopic lever 9 by means of a plurality of rivets 23. The 
telescopic lever 9 is urged by the plate spring 22 so as to move the lever 
9 on an incline in the direction C in FIG. 8 so that the locking lever 9 
is reliably engaged with the recessed portion 19 of the main body 1a of 
the steering wheel 1 and is easily released therefrom. 
The operation according to the invention is as follows: 
If the driver wishes to adjust the steering wheel 1 forwardly or rearwardly 
according to the physique of the driver, the telescopic lever 9 is engaged 
with the recessed portion 19 of the main body 1a of the steering wheel 1 
by moving the lever 9 from the locked position A to the unlocked position 
B against the biasing force of the spring 21. The locking rod 8 is rotated 
according to movement of the telescopic lever 9 and the locking force 
between the steering shaft 2 and the outer cylinder 5 by the locking 
member 6 is discontinued. Accordingly, the steering shaft can be shifted 
forwardly and rearwardly within the outer cylinder 5. 
If the engagement between the telescopic lever 9 and the main body 1a of 
the steering wheel 1 is manually released after the forward or rearward 
adjustment of the steering wheel 1, the telescopic lever 9 is 
automatically returned to the locked position A by the biasing force of 
the spring 21. The locking rod 8 is rotated in the opposite direction to 
the aforementioned unlocked state by return of the telescopic lever 9 and 
the locking member 6 is expanded so that the steering shaft 2 and the 
outer cylinder 5 are locked. 
By the foregoing, there has been disclosed a preferred form of a locking 
mechanism for a telescopic steering wheel constructed in accordance with 
the present invention. It will be appreciated that various additions, 
substitutions, modifications and omissions may be made thereto without 
departing from the spirit of the invention.