Note: Descriptions are shown in the official language in which they were submitted.
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TILTABLE STEERING CO~llMN Wm-I PLAY PROVIl)ED
BETWEEN TWO ~lLT MECILANISM PAWL Rl~ ASE MI~ANS
BACKGROUND OF l~lE INVENTION
The present invention relates to a tiltable steering column for an
10 automotive vehicle, and more particularly relates to such a tiltable
stee~ing column for an automotive vehicle, which L5 su~tsble for being
adju.sted so as to conform the driving position to the p~rticular
physical buiid and preference of an individual driver, which is
improved in term~s of fittability and assemblabi1ity.
As an ove~all constructlon, a tiltsble steering column for an
automotive vehicle comprises a main steerinF shaft comprising a lower
steering shaft and an upper steering shaft tiltabb rot~Uonally
connected to said lower steering shaft, and a column tube a~sembly,
~0 comprlsing a lower tube which rotatabb supports said lower steering
sha t from the body of said automotive vehicle, and an upper tube which
rotstabb supports sdd upper steering shaft and is pivotslly mounted
so as to be able to tiit relative to sald lower tube. Further, it i~s
known for such a tiitable steering cohlmn for an automotive vehicle to
25 comp~ise a tiit locXing mechanism which comprises a ratchet mechanism
comprising: a ratchet fixed4r attached to one of said upper tube and
said lower tube; a pawl plvot~lly attached to the other of said upper
tube and said lower tube; a means for biadng said pawl so as to
engage it with said ratchet, which acts constantly; and a means for
30 selectively bia~;ing ssid pawl so a~ to reiea~e its said engagement with
said ratchet. Thereby, by operaUng the reiea~ng means for the pawL
; the engagement of the pawl to the ratchet is released, and the upper
tube csn be rotatabb tilted with respect to the lower tube, thus
enabling the position of the steering wheeL which is fixed to the
35 upper end of the upper steering shaM, tn be ad~usted so as to confo~n
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the driving position to the particular physical build and
preference of an individual driver.
According to such a tiltable type steering column,
for instance the ones disclosed in Japanese Utility Model
Publication Serial No. 57-53730 t 1982) and Japanese
Uti l i ty Model Layi ng Open Publication Serial No. 5 8 -
163354 (1983), neither of which is it intended to admit
as prior art to the present application except to the
extent otherwise required by law, the upper tube is
rotationally locked with respect to the lower tube and
thus the vehicle body by the tilt locking mechanism; but,
6ince the tilt locking mechanism is in principle provided
only on one side of the steering column assembly, the
lateral 6upport rigidity for the upper tube is not always
sufficient, and good vibrational characteristics cannot
be assured in all cases. And, in the worst ca6e,
sideways 6kewing of the steering wheel could in principle
occur.
In view of these problems, the present applicant, in
Japanese Utility Model Application Serial No. 59-106772,
which again it is not intended hereby to admit as prior
art to the present application except to the extent
otherwise required by law, has proposed a tiltable
steering column in which two such tilt locking
mechanisms are located one on each side of the steering
column; and the two release levers of these two tilt
locking mechanisms are synchronized by way of a
connecting shaft.
As a result of this arrangement, in such a tilt
steering device, since the upper tube of the steering
column is ~upported by a pair of tilt loc~ing mechanisms
arranged on both sides of the steering oolumn, the
lateral rigidity of the support of the upper tube can be
increased, and good vibrational characteristics can be
obtained, with the additional advantage that, since the
release levers of the two tilt locking mechanisms
are synchronized, the rotational operation of only
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one of the release levers is requlred for releasing the lockin~ actionof the two tllt locking mechanisrns, and accordingly the operability of
the device is quite good.
The problem however arises that, since the two ~sides of the upper
and lower tubes are individually locked together by the two ti]t
locking mechani.~3ns, the accuracy of fitting of these mechanisms is
cruciah Specifically, a slight difference in the phases of the teeth
o~ the two ratchets, or other divergence from the Ideal due to
manufacturing varlatlons of the parts, can prevent the proper
engagement of one of the two tilt locking mechanisms, and it is
extremely difricult to properly ensure s~nultaneous me,shina of the two
pawls with the two ratchets, because of the inevitability of
dimenslonal variations dr the parts dur~ng manufacture, as well as
because of the inevitability of assembly varlations of the steering
column structure.
SUMMARY OF THE INV~ON
~ 20 Accordingly, It ~s the primary object of the present invention to- provlde a tUtable steering colun~, whlch avolds the above described
problemæ.
It Is a further ob~ect of the present invention to provide such a
tlltab}e steering column, whl~h provides ~ood stabllity for the support
of the upper tube member thereof and for the stee~ing wheeL
It is a further object Or the present inventlon to provide such a
tlltable stee~ing column, which is not prone to any sideways skewinl~ of
the steellng whe~
lt is a yet further ob~ect Or the present inventlon to provide
such a tUtsble steerlng column, whlch has two such tUt locking
mechsnisms on eltller side of the steering coh~mn, snd which is not
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prone to difficulties with proper simultsneous engagemellt o~ said tllt
lockinF mechanlsms.
It is a yet further object of the present invention to provide
5 such a tiltable steerinF column, which has two such tilt lockinF
mechanisms on either side of the steering column, and in which said two
tilt locking mechanisms can both rel;ably be simultaneou.qly engaged.
It is a yet further object of the present invention to provide
10 such a tiltable steering column, the operaUon of which does not suffer
unduly due to moderate deviances from msnufacturing or assembly
specifications.
It is a yet hlrther object of the present invention to provide
15 such a tiltable steering column, which has good vibrational
chsracteri~qtics.
lt is a yet further object of the present invention to provide
such a Ultable steering column, which has good assemblability.
According to the most genersl aspect of the present invention,
these and other ob~ects are accomplished by a tiltable steering column
for sn automoUve vehicle, comprLsing: (a) a main steering shaft
comprising a lower steering shaft and an upper steering shaft rotatsbly
25 connected to snid lower steering shaft; ~b) a column Ulbe assembly,
comprislng: ~b1) a lower tube which rotatably support~s said lower
steering sha~t from the body ol sald automoUve vehicle; and (b2) an
upper tube which rotatably supports ssid upper steerin~ shaft and is
pivotally mounted so as to be able to Ult relaUve to said lower tube
30 at least in a substanUslly verUcal plane; and: (c) a tilt locking
mechanism, comprising a first side ratchet mechsnLsm on one side of
said column tube assembly and a second side ratchet mechanism on the
other side of ssid column tube assembly, each comprising: (cI) a
ratchet fixedly attached to one of said upper tube and said lower tube;
35 (c2) a pawl pivotally attached to the other of said upper tube and said
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lower tube; (c3) a means fvr bia~n~ s id pawl so llS to engage lt with
said ratchet, which acLs constantly; and: ~c4) a means for selectively
biasing said pawl so as to release its said engagement with said
ratchet; and further comprising: (d) a means for coupling the
5 operation of said pawl relea.<;ing means to~ether with a certain amount
oI play being available therebetween.
According to the present invention as described above, since the
coupling together of the side ratchet mechanisms by the coupling means
10 provides a cerhin smount of play between said side rstchet mech~i~ns,
the problem of matching together the engsgement of said two side
ratchet mechanisms is essentially solved, and mismatching of the pha.ses
Or the pawls to the teeth of the ratchets can be easily compen.sated for
without causing any operational problems. ~Ience, at least one of the
15 two side ratchet mechanisms can be positively engaged, and there is
provided a tiltable steering column which overcomes the problems
outlined above with respect to other constructions, and which provides
good stability Ior the support of the upper tube member thereof and for
the steering wheeL as well as not being prone to any sideways skewing
20 of the steering wheeL Further, this tiltable steering column has two
tilt locking mechanisms on either side of the steering column, and yet
is not prone to difficulties with proper simultaneous engagement of
said tilt locking mechanisms, and does not suffer unduly due to
moderate deviances irom manufacturing or assembly specifications.
25 Thus, this tiltable steering column has good assemblability and good
vibrational characteristics.
BRlE~ DESCRlPTlON OF TlIE DRAWINGS
The present invention will now be shown and described with regard
to certain of the preferred embodiments thereof, and with reference to
the illustrative drawings, which however should not be considered as
limitative of the present invention in any way, since the scope of the
present invention is to be considered as being delimited solely by the
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accompanying claims, rather than by any particulsr features of the
disclosed embodiments or of the drawings. In these drawings:
l~g. 1 is a partly schematic sectional view of the first preferred
5 embodiment of the tilt steering colwnn assemb4r of the present
invention taken in a sectional plane containing the longitudinal axis
of said column assembly (which is shown as extended substantially
straight) and parallel to the transverse axis of the vehicIe to which
said column assembly is fitted;
Fig. 2 is a side view of said first preferred embodiment tilt
steering column a.ssembly, shown in its state of being mounted to a
vehicle body;
Fig. 3 is a side view of a first tilt locking mechanism shown in
Fig. 1, shown at a magnified scale and at one stage of its operation;
Fig. 4 is a vlew similar to Fig. 3, showing said first ti]t
locking mechanism at another stage of its operation;
Fig. 5 is a vlew similar to Figs. 3 and 4, showing said first tilt
locklng mechanism at yet another stage of its operation;
Fig. 6 is a side view of a first release lever, incorporat~i in
25 the first tilt locking mechanism of Figs. 3 through 5;
Fig. 7 is a sectlonal view of said first release lever as taken in
a plane shown by the arrows VII - VII in Fig. 6;
Fig. 8 is a side view of a cover plate incorporated in said first
tilt locking mechanism;
Fig. 9 is a side view of a second release lever incorporated in
sald first tilt locking mechanism;
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Fig. 10 is a slde view of a third release lever incorporated in a
second tilt locking mechanism;
Fig. 11 is a sectional view of said third release lever as taken
5 in a plane shown by the arrows XI - XI in Fig. 10;
Fig. 12 is an end on view of a connecting lever which connects the
first and the third levers shown in Pigs. 6 and 10, of the first and
second tilt locking mechani.sms;
Pig. 13 is a side view of said connecting lever of F~g~ 12;
Pig. 14 is a longitudinal secUonal view of an ad~ustable
construction for rotatably mounting a pawl of said fir.st ti]t locking
15 mechanlsm to a fLlced member; and
Pig. 15 is a transverse sectional view of said ad~ustable
construction, as taken in a plane shown by the arrows XV - XV in
Fig. 14.
DI~SCRlPI~ON OF T~E PRI~FERI~ED EMBODlMENTS
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The present inventlon will now be described with reference to the
preferred embodiments thereof. F~. 1 is a longitudinal sectional view
25 of the first preferred embodiment of the tilt steering col~mn assembly
of the present invention taken in as near a horizontal sectional plsne
as possible containing the lon~it~ldinal axis of said column assembly,
and Fig. 3 is a side view of said tilt steering column assembly shown
in its state of being mounted to a vehicle body. In these figures, the
30 reference numeral 10a denotes an upper stee~ing shaft assembly, which
Ls made up from a first shaft 11 and a second shaft 12; and similarly
the reference numeral 10b denotes a lower steering shaft a.s.sembly,
which i~ made up from a third shaft 13 and a fourth shaft 14. In said
upper steering shsft assembly 10a, ssid first shaft 11 is rotationally
35 coupled to said second shaft 12 but Ls left free to move axial4r with
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respect thereto, by a male splined portion on the right
end in Fig. 1 of 6aid 6econd shaft 12 being fitted
engagingly with a female splined portion formed on the
left end in Fig. 1 of said first shaft 11. On the other
hand, in 8 aid lower steering 6haft assembly 1Ob, said
third shaft 13 is coupled to said fourth shaft 14 both
with regard to relative rotational movement therebetween
and with regard to relative axial movement therebetween,
by a portion on the right hand end in Fig. 1 of 6aid
fourth shaft 14 being fitted over and being fixedly
coupled to a portion formed on the left end in Fig. 1 of
said third shaft 13, 6aid coupling being quite weak so as
to allow for collapse of the steering column assembly in
an impact situation. And the left end in Fig. 1 of the
second shaft 12 is coupled to the right end in ~aid
figure of the third shaft 13 by a universal joint 15 of a
per se known sort, thus rotationally coupling the upper
and lower steering shaft assemblies lOa and lOb together
while allowing some bending between them; and the left
end in the figure of the fourth shaft 14 is connected via
a universal joint to a stub shaft 16 which leads to a
steering box, not particularly shown, while a steering
wheel W, not ~hown in Fig. 1 but shown in Fig. 2, i6
mounted on the right end in the figure of the first shaft
11, which is adapted for mountingly receiving it.
A steering column tube as6embly is fitted around
this steering shaft assembly, said a66embly compri~$ng an
upper tube 21 which rotatably 6upports the first shaft 11
of the upper shaft assembly lOa via a pair of bearings,
and a lower tube 22 which rotatably supports the fourth
shaft 14 of the lower shaft assembly lOb by a bePring.
~he lower tube 22 is fixedly mounted to the vehicle body,
hanging below the instrument panel thereof, via a main
fixing bracket 23 attached to a higher portion of said
lower tube 22 and an auxiliary fixing bracket 24
attached to a lower portion of said lower tube 22.
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A tubular portion 25a of a rotatable bracket 25 i~
slidably fitted over the upper tube 21, and this
rotatable bracket 25 is supported, so as to be rotatable
around a horizontal axis substantially transverse to
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the body of the vehicle, by the two sides as seen in Fig. 1 Oe the main
fixing bracket 23. This sliding of the upE~er tube 21 in the tubular
portion 25a of the rotatable bracket 25 is selectively fixable, by the
driver of the vehicle operating a lock mechanism 26 by actuating a
5 release lever 26a. Thus, by the driver actuatinç~ said release lever
26a so as to release the locking of the upper tube 21 tll the rotatable
bracket 25, the upper tube 21 becomes able to axially slide with
respect to said rotatable bracket 25 with the second shaft 12 sliding
inside the first shaft 11, thus providing axial adjustment of the
10 steering wheel W and allowing telescopic operation of the steering
column as a whole.
Extending between the main fixing bracket 23 and the rotatable
bracket 25 there are provided a pair of tension coil springs 27a and
15 27b, one on each side of the steerlng column assembly, and these
sprJngs 27a and 27b constantly urge said rotatable bracket 25 in the
counterclockwise direction in Figs. 2 through 5, so as to
counterbalance the weight of the upper tube 21, the upper steering
shaft assembl~r 10a, the steering wheel W, and so on. Further, a pair
20 of tilt locking mechanisms, denoted as 30 and 40, are provided, one on
each side Or the steering column assemb4r, for selectively either
locking together the main fixing bracket 23 and the rotatable bracket
25, or releasing said locking together of said main fixing bracket 23
and said rotatable bracket 25 so that they can rotate with respect to
25 one another about said horizontal axis substantially tran~sverse to the
body of the vehicle, thus providing tilting adju~stment ror the steering
wheel W and allowing tilting operation as a whole of the steering
column.
The first one 30 of these tilt locking mechanisms will now be
described, with reference to Figs. 3 throu~h 5 which show it as a whole
and Figs. 6 through 9 which show certain individual parts o~ it. This
first tilt locking mechanism 30 comprises a ratchet 31, a pawl 32, a
first release lever 33, a cover plate 34, and a second release lever
35.
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To the lower left side as seen iTI Fi~s. 3 throuFh 5 oi the
rotatable bracket 25 there Ls fixedly secured the ratchet 31, which is
a substantially planar member and flmctions as a support member for
said rotatable br~cket 25 and for the steering wheel W and the tiltable
5 portion of the steering colurnn as a whole, by bein~ rotatably fitted
over a sleeve provided on a mounting bolt 36b which is fixed to the
main ~ixing bracket 23. Thereby, the aforesaid horizontal axis
substantially transverse to the body of the vehicle about which the
steering wheel W and the steering column as a whole tilt Ls defined.
lV An edge portion of this ratchet 31 is formed with a circumferentially
extending arcuate toothed portion 31a.
Likewise, the pawl 32 iq a substantial~y planar member, and is
pivotally mounted to the main fixing bracket 23 by being rotatably
fitted over a sleeve provided on another mounting bolt 36a which is
likewise fitted to the main fixing bracket 23 and by being retained
thereon by a nut 36h; the full detaiLs of this fitting con.struction
will be explained hereinafter. And this pawl 32 is formed with an
arcuate toothed portion 32a opposed to and confronting the arcuate
toothed portion 31a of the ratchet 31. Thereby, when the pawl 32 is
rotated about its molmting bolt 36a in the clockwise direction from the
point of view of Figs. 3, 4, and 5, to its position as seen in ~ig. 4
or Fig. S, its arcuate toothed portion 32a is disengaged from the
arcuate toothed portion 31a of the ratchet 31, and accordingly the
25 rotation of the steering wheel W and the tiltable portion of the
steering column as a whole with respect to the fixed main fixing
bracket 23 around the axis defined by the mounting bolt 36b is not
substantially impeded thereby; but, on the other hand, when said pawl
32 is rotated in the anticlockwise direction from the point of view of
30 Figs. 3, 4, and 5 to its position as seen in Fig. 3, then its arcuate
toothed portion 32a is engaged to the arcuate toothed portion 31a of
the ratchet 31 somewhere along it, and accordingly the rotation of the
steering wheel W and oi the tiltable portion of the steering column
assembly as a whole with respect to the fixed main fixing bracket 23
35 around said axis defined by the mounting bolt 36b is prevented, and the
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upper portion of the steering column along with the wheel W are
effectively locked into place.
For releasing this meshing engagement between the pawl 32 and the
5 ratchet 31 there is provided the first relea,se lever 33, and this is
formed of a lever 33a and an auxiliary plate 33b fitted thereto as
extending generally parallel thereto; these members can best be seen
in Figs. 6 and 7, whlch show said first release lever 33 in side view
and in secUonal view respecUvely. This lever 33a and aw~liary plate
10 33b are connected together via the axis of a roller 33c extending
between them, and both have apertures, confronting one another, which
are fitted over the mol~nting bolt 36b previously mentioned, so as to
mount the first release lever 33 to the main ii~ing bracket 23 in a
rotatable manner around; the same transverse horizontal axis for Ulting
15 the steerlng column assembly, previously defined. A cam groove 33d is
iormed on a portion of the lever 33a, and an engagement pin 32b formed
on the pawl 32 i~s fitted into this cam groove 33d so as to slide
therein and so as to be guided thereby. One end of a tension coil
spring 36c (see Fig. 3) is fitted to a hole formed in the lever 33a,
20 and the other end of said tension coil spring 36c is hooked to a point
on the main i'L~dng bracket 23, and thereby the iirst release lever 33
is biased in the clockwise direction as seen in Fig. 5, so as ~provided
the end 33a of said first release lever 33 is not impelled by the hand
of the driver) to press the roller 33c against the back of the pawl 32
25 and so as thereby to press said pawl 32 in the anticlockwise direction,
so as to urge lts toothed portion 32a to be meshed with the toothed
po~tion 31a Or the ratchet 31 as seen in Fig. 5.
A side view of the cover plate 3~ is shown in Fig. 8. This cover
30 plate 34 is used for defining the porUon of the toothed shaE~e 31a on
the ratchet 31 to which the toothed shape 32a of the pawl 32 engages~
i.e. for shielding the portion of sald ratchet 31 to which it is not
desired that sald pawl 32 should engage. The cover plate 34 comprises
an arcuate cover portion 34b molmted on the end of a plate portion 34a.
35 The arcuate cover portion 34b has a set of teeth 34d formed on its
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concave inner sur~ace, and a projectioll 34c extends outwards from the
other side of said cover portion 34b. At the other end of said cover
plate 34 there are provided an engagement pin 34f and an arcuately
curved sheet spring 34e. This cover plate 34 is fitted over the
5 mounting bolt 36b, on the outside of the ratchet 31, by an elongated
hole formed in said cover plate 34. In this state, the sheet spring
34e engages to the back side of the rutchet 31, and the cover plate 34
both is rotatable around the axis of the mounting bolt 36b and Lq also
slidable sideways thereon through a certain distance, either so as to
10 engage the teeth 34d formed on the in.side of its arcuate cover portion
34b to a particular contiguous set of the teeth 31a formed on said
ratchet 31, or alternatively so as to disengage said teeth 34d and 31a
from one another; and the sheet spring 34e bla.ses the cover plate 34
in such a direction as to press said teeth 34d and 31a into mutual
15 engagement. Thereby, the arcuate cover portion 34b serves to blank off
a part of the toothed portion 31a of the ratchet 31, leaving that
particular covered portion of said ratchet 31 effectively smooth and
free from teeth. And, in the above described state wherein said teeth
34d and 31a are moved apart from one another and disengaged, by the
20 pushing of the cover plate 34 in the leftward direction in Fig. 8
against the biasing action of the leaf spring 34e which is overcome,
the cover plate 34 can be rotated around the axis of the mounting bolt
36b, so as to change the aforesaid portion of the toothed portion 31a
of the ratchet 31 which is blanked off by said cover plate 34.5
in Fig. 9 there is shown in side view the second release lever 35,
which is for adjusting the above described mutual meshing position of
the cover plate 34 relative to the ratchet 31, by lifting and sliding
the cover plate 34. Said second relea.se lever 35 comprises a main
30 plate portion 35a, a lever portion 35b extending therefrom, a cam
aperture 35c formed therein, and an engagement pin 35d extendinF
sideways therefrom. And this second release lever 35 is fitted, via a
hole formed therein, over the mounting bolt 36b between the first
release lever 33 and the cover plate 34. A retainer plate 36d is
35 fitted over the whole assembly, as best seen in Fig. 1, and a tension
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co~ spring 36e is stretched between a projection oî said retainer
plate 36d and the lever portion 35b o~ the second release lever 35;
thereby, said second release lever 35 is biased in the clockwise
direction as seen in Fig. 3, and its clockwise rotation is stopped when
5 a portion of it comes into contact with a bolt 36i fitted to the
retainer plate 36d. In this condition, the engagement pin 34f of the
cover plate 34 faces and engages with the cam groove 35c of said second
release lever 35. A ~lide plate 37 is assembled to the outside of the
fixed bracket 23 and an engagement depression 37a of the ~l~ide plate 37
10 opposes the projection 34c o~ the cover plate 34, so as to limit the
rotation of the cover plate 34 when said cover plate 34 makes a sliding
motion and the projection 34c enters into said depression 37a.
The second one of these tilt locking mechanisms will now be
15 described, with particular reference to Figs. 10 and 11. Said second
tilt locking mechanism 40 comprises a ratchet 41, 8 pawl 42, and a
third release lever 43. The ratchet 41 and the pawl 42 are similarly
formed and arranged to the ratchet 31 and the pawl 32 of the first tilt
locking mechanism 30 described above. The third release lever 43 is
20 for disengaging the meshing of the pawl 42 and the ratchet 41, which
are assembled to the main fixing bracket 23 on the other side of it
from the first tilt locking mechanism 30 by a mounting bolt 44a and
another mounting bolt shown in the figures but not designated by any
reference numeral, and comprises a lever member 43a and an auxiliary
25 plate 43b fitted thereto as extending generally parallel thereto;
these members can best be seen in Figs. 10 and 11, which show said
release lever 43 in side view and sectional view re.spectively. The
mounting bolt 44a is subs~antially coaxial with the mounting bolt 36b
for the first tilt locking mechanism 30, and like it also serves for
30 pivoting the upper tube 21 to the main flxing bracket 23 so that it is
rotatable around the previousl~r defined horizontal tilt axis
substantially transverse to the body of the vehicle. The lever 43a and
the auxiliary plate 43b of the third release lever 43 are connected
together via the axis of a roller 43c extending between them, and both
35 have apertures, confronting one another, which are fitted over the
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mounting bolt 44a for the ratchet 41 previously mentioned, so as to
mount the third release lever 43 to the main fixing bracket 23 in a
rotatable manner arolmd the same transverse horizontal tilt axis 8S
previously defined. A cam groove 43d is formed on a portion of the
lever 43a, and an engagement pin 42b formed on the pawl 42 is fitted
into this cam groove 43d so as to slide therein and so as to be guided
thereby. One end of a tension coil spring 44b (see Fig. 3) is fitted
to a hole formed in the lever 43a, and the other end of said tension
coil spring 44b is hooked to a point on the main fixing bracket 23, and
thereby the third release lever 43 is biased in the direction so as
(provided the end of the lever 43a is not impelled by the hand of the
driver of the vehicle) to press the roller 43c against the back of the
pawl 42, so as to press said pawl 42 in the direction to engage its
toothed portion with the toothed portion of the ratchet 41.
The particular means by which the pawl 32 of the first tilt
locking mechanism 30 is rotatably mounted to the main fixing bracket 23
will now be particularly explained with reference to Figs. 14 and 15,
which are a longitudinal sectional view thereof and a sectional view
thereof as taken in a plane shown by the arrows XV - XV in Fig. 14,
respectively. In detaiL over the previously mentioned bolt 36a, which
is fixedly mounted to the main fixing bracket 23 by spline means formed
proximate to the head portion of said bolt 36a, there is fitted an
eccentric collar 36f which is formed as a tubular eccentric cam with
two ilats on its end portion. ln other words, the middle portion of
this collar 36r, over which the cam 32 fits and on which said cam 32
turns, is formed with a cylindrical inner surface and with a
cylindrical outer surface which are eccentrically off.set from one
another by a certain distance L; and the cylind~cal inner surface
rotatably slides on the outer surface of the mounting bolt 36a, while
on the cylindrical outer surface there is rotatably mounted the cam 32.
And on the end portion of this collar 36f, over the two flats formed
thereon, there is fitted a spacer 36g whose outer suriace is formed in
a hexagonal shape. The whole construction is retained by the nut 36h
35 fitted onto the end Or the mounting bolt 36a. As a result, the
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rotation of the spacer 36F causes an lntegral rotation of the eccentric
collar 36f, thereby allowing the center of the swinging motion of the
pawl 32 to ~e adjusted within a range of plus L to minus L. The
eccentric collar 36f is located between the main fixing bracket 23 and
5 the retainer plate 36d, and is restricted from rotational motion aîter
the devlce is ~itted and after the above described positioning
adjustment has been completed, by the fastening ~orce of the mlt 36h
when fully tightened, which longitudinally compresses said eccentric
coilar 36f.
The first release lever 33 of the first tilt locking mechanism 30
and the third release lever 43 of the second tilt locking mechanism 40
are connected together by a connecting member 38, which is shown in end
on view in Fig. 12 and in side view in Fig. 13. This connecting member
15 38 is a lever which is bent into an L-shape, and a plate portion 38a
thereof is rotatably fitted onto the molmting bolt 36b between the
cover plate 34 and the second release lever 35. A connection pin 38b,
provided on said plate portion 38a, is fitted into a connection
aperture 33e formed in the first release lever 33, while an arm portion
20 43e formed on the third release lever 43 is fixed by bolts or other
~uitable means to an arm portion 38c extending from the lower end of
the plate portion 38a of the connectin~ member 38 in the rightward
direction as seen in Fig. 13. Thus, the first release lever 33 and the
third release lever 43 are connected together, so that the rotational
25 operation of the first release lever 33 causes the rotation of the
connection member 38 which in turn causes the rotation of the third
release lever 43.
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llowever, particularly according to the concept of the present
30 invention, as can best be seen in Fig. 6, the connection aperture 33e
formed in the first release lever 33 is shaped as a somewhat elongated
circular arc with center the center of rotation of said first release
lever 33, and the connection pin 38b of the connectlon member 38 fits
into this connection aperture 33e with a certain amount of free play
35 remaining in the circumferenUal direction. In other words, the
~73;~7~3
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a~oresaid rotational coupling toFether of the first relesse lever 33 of
the first tilt locking mechanism 30 and the third release lever 43 of
the second tilt locking mechanism 40 is provided, only with a certain
amount of rotational play therebetween.
in the first and third release levers 33 and 43, the cam grooves
33d and 43d respectively provided are formed in an asymmetric manner,
and there is a certain time lag in the meshing and the release of
meshing of the pawls 32 and 42 with their respective ratchets 31 and
41. The cam groove 33d of the first release lever 33 (vide Fi~. 6) is
formed with an arcuate portion 33dl at its proximal end portion the
center of which is the central axis of the mounting bolt 36b, and with
a cam portion 33d2 at its free end portion. On the other hand, the cam
groove 43d Or the third release lever 43 is formed with a cam portion
43dl at its proximal end portion and with an arcuate portion 43d2 at
its free end portion the center of which is the central axis of the
mounting bolt 44a. Thus, when the first and the third relea.se levers
33 and 43 rotate, the pressures of the rollers 33c and 43c on the pawls
32 and 42 respectively actuated thereby are released at the same time,
20 but, thereafter, the pawl 42 is displaced from the ratchet 41 to be
disengaged therefrom first and then subsequently the pawl 32 is
dlsplaced from the ratchet 31 to be disengaged therefrom. And, when
the two pawls 32 and 42 mesh with their respective ratchets 31 and 41,
the pawl 32 has a priority.
The lock mechanism 26 for selectably preventing the sliding of the
upper tube 21 in the rotatable bracket 25 will not be particularly
described with regard to its structure, because it is not directly
relevant to the concept of the present invention; suffice it to say
30 that said lock mechanism is selectably actuated by the driver by the
operaUon of the relea~se lever 26a.
The relevant portions of the operation of this tilt steering
device as described above will now be explained.
127~;~7{)
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In the condition that the driver does not operate the flrst
release lever 33 of the first tilt locking mechanism 30, then the
rotatable bracket 25 is locked to the main fi~ng bracket 23 by means
of the two tilt locking mechanisms 30 and 40. In this state of the
apparatus, the first tilt locking mechanism 30 is in its state as shown
in Fig. 3, with its pawl 32 engsged with its ratchet 31; snd the
second tilt locking mechanism 40 is also in a similar state, muhtis
mutandis, with its pawl 42 engaged with its ratchet 41, and with its
third release lever 43 in a like position to that of the first release
lever 33.
When the hand of the driver, from this locked state, is applied to
the end of the first relesse lever 33 of the first tilt lockmF
mechanism 30 so as to rotste said first release lever 33 in the
counterclockwise direction as seen in Fig. 3, then the connection
member 38 and the third release lever 43 of the second tilt locking
mechanlsm 40 are rotated in the ssme direction, albeit with a
relstively slight and bssically insignificant at this time delay due to
the provision of the elongated shspe for the connection aperture 33e as
explained above. As a result, the pressures exerted on the pawls 32
and 42 respectively by the rollers 33c and 43c provlded on the first
and thlrd release levers 33 and 43 respectively of the first and second
tllt locking mechalusms 30 and 40 are released substantially at the
same time, but, because of the di~ference in the forms and the actions
of the cam grooves 33d and 43d, the pawl 42 of the second tilt locking
mechanism 40 is displaced from its ratchet 41 first to release said
second tilt locking mechanism 40, and only subsequently is the pawl 32
Or the first tilt locking mechanism 30 displaced irom its ratchet 31 to
release said first tilt locking mechanism 30. This effect, of ~irst
releasing that one of the tilt locking mechanisms which is dLsplaced
sideways i~om the first release lever 33 which is being manually
operated, is done in order to prevent the type of twisting of the
mechanism that mi~ht occur if the reverse condition were to prevail.
When the locking or the rotatable bracket 25 to the main fixing bracket
23 by the two tllt locking mechanisms 30 and 40 has been thus released,
127;~;~71)
-- 18 --
then by the actions of the tension coil sprin~s 27a and 27b the
rotatable bracket 25 as well as the upper tube 21, the upper shaft
assembly 10a, and the steering wheel W are lifted up ~possibly with
some slight mamlal a~Lst by the vehicle driver), and the posiUon of
5 the elements of the first tilt locking mechanism 30 becomes as shown in
Fig. 4.
the inner teeth 34a of the arcuate portion 34b of the cover plate
34, in this situation of the first tilt locking mechanism 30, are still
10 meshed with the same ones of the teeth 31a of the ratchet 31 with which
they were previously meshed, not having moved with respect thereto, and
the pawl 32 has raised up from those of the teeth 31a of said ratchet
31 with which it was previously meshed, and is now confronting the
smooth outslde surface Or said arcuate portion 34b of said cover plate
15 34. Therefore, when from this positlon of the apparatus the driver
slmply pushes downwards on the steering wheel W (without sctuating sny
control lever), the pawl 32 which was being pressed by the roUer 33c
now slides over the smooth outside surface of said arcuate portion 34b
of said cover plate 34, until it reaches those of the teeth 31a of ssid
20 ratchet 31 with which it was previously meshed, and then it snaps
downwards thereagainst and bcks to those particular teeth again. And,
at this time, in the second tilt locking mechanism 40, the roller 43c
presses the pawl 42, but, before the meshing of the ratchet 31 snd the
pawl 32 of the first tilt locking mechanism 30 has occurred as
25 described sbove, the ratchet 41 and the pawl 42 of said second tilt
locking mechanism 40 are still dlsplaced from one another by the action
of the engsgement pin 42 and the cam groove 43d as explained above, and
the pawl 42 and the ratchet 41 mesh together only substantiaUy
immediately after the meshlng of the ratchet 31 and the pawl 32 of the
30 first tilt locking mechanism 30. Thus, this tllt locking system is
equipped with a so caUed memory function, and as a result the steering
wheel is always returned to the set initial position, as described
above.
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.:
~73 ~7~)
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The way in which thls memorized positlon of the steerinK wheel W
may be adju.sted will now be explained. In thls case, from the state of
the members of the first tilt locking mechsni,~n shown in l~iF. 3, the
second release lever 35 is rotatlonally moved by the vehicle operator
5 in the anticlockwise direction as seen in the fig~Ire. As a result, the
cover plate 34 is slidably moved to the left as seen in I;~. 3 by the
acUon of the engagement pin 34f and the cam groove 36c of the second
release lever 35, and it~s cover porUon 34b is dLsplaced from the
ratchet 31 with its teeth 34a becoming disengaged from the ratchet
teeth 31a, while the projection 3~c of the cover plate 34 enters the
engagement depression 37a of the guide plate 37. Therefore, the cover
plate 34 now aan be rotated with respect to the ratchet 31. And, when
the second relesse lever 35 is hlrther rotaUonally operated, the
engagement pin 3Sd provided on said second release lever 35 Ls engaged
15 with the first release lever 33 so as to integrally rotate it. As a
result, the third release lever 43 oi the second tilt locking mechanism
40 is slmultaneously rotated by way oi the connection member 38, and,
as shown in fig. 5, the locking of the fixed bracket 23 to the
rotational bracket 25 by the two Ult locking mechanisms 30 nnd 40 is
20 released. Therefore, the steering wheel W may be moved vertically,
either upwards or downwards, while the second release lever 35 Ls
retained at its rotational posltlon. And, after the steering wheel W
has been vertically ad~usted to its desired posiUon, the releasing of
the operaUon of the second release lever 35 callses the rotational
25 restoration of the first and the third release levers 33 and 43,
thereby causing the pawls 32 and 42 to now mesh with portions of the
arcuate teeth porUons 31a and 41a of their ratchets 31 and 41 which
are different from the positions with which they were previously
meshed. Thereafter, the second release lever 35 rotationalbr restores
- 30 itself, and returns the cover plate 34 back to its non operaUonal
position so as to now make its teeth portion 34d mesh with and cover a
portion of the arcuate teeth portion 31a of the ratchet 31 which is
different from the previously meshed with and covered portion. LTI this
; case, the teeth porUon 34d of the cover plate 34 meshes with a teeth35 porUon 31a of the ratchet 31 which is angularly displaced from the
.
~;~7~
- 20 -
previous teeth portion which was meshed with the opposing member prior
to the positional adjuslment of the steering wheel W, just by the angle
through which the steering wheel W has been adjusted, and the newly
adjusted position of the steering wheel W is thus memori7~d.
Accordin~ to the shown construction, therefore, the upper tube 20
and the upper steering shaft assembly lOa and the steering wheel W
mounted thereon can be supported on the two sides of the main fixing
bracket 23 which is fixedly secured with respect to the lower tube 22,
10 by means of the two tilt locking mechanisms 30 and 40 the operation of
which is linked together as explained above. Therefore, it has become
possible to obtain very good vibrational characteristics o the entire
construction, by increasing the rigidity of the locking support of the
upper tube 21 and its associated members. In this shown construction,
15 since the first and the third release levers 33 and 43 are connected
together for synchronization by the connecting member 38, the
operability of the first and second tilt locking mechanisms 30 and 40
is quite favorable.
Particularly according to the concept of the present invention,
since a small amount of play is provided in the coupling between the
first release lever 33 oi the first tilt loclcing mechani,sm 30 and the
coupling member 38 by, in this first preferred embodiment, forming the
connectlon aperture 33e in the first relea.se lever 33 as shaped as a
somewhat elongated circular arc with center the center of rotation of
said first release lever 33, and by arranging the fit of the connection
pin 38b of the connection member 38 into this connection aperture 33e
to have a certain amount of free play remaining in the circumîerential
direction, thereby when fittlng together the two tilt locklng
mechanisms 30 and 40 and the steering column a.ssembly as a whole, there
is a certain degree of freedom available between these two tilt locking
mechanisms 30 and 40, and this degree of freedom absorbs any
misalignment which might otherwise deteriorate the meshing state of the
pawls 32 and 42 with the ratchets 31 and 41 which may have arisen due
to manufacturing variations of the structural elements of said two tilt
~73~ 1~
- 21 --
lockin~ mechanisms. Thus, lt is possible to ensure thnt the pawls 32
and 42 engage properly and positively with their ratchets 31 and 41 at
all times, without any problems arising with precise alignment of the
components of the two tilt locking mechanisms 30 and 40 du~ng assembly
5 of the construcUon.
Since in this construction the pawl 32 of the first Ult locking
mechanism 30 is assembled to the device by the use of the eccentric
pivoting means incorporating the mounUng bolt 36a, the eccentric
collar 36f, the spacer 36g, and the fastening nut 36h and so on, as
shown in Figs. 14 and 15 in detail, thereby as explained above by
turning the eccentric collar 36f and the spacer 36f integrally fitted
therewith in assembllng the pawl 32 to the first Ult locking mechanism
30, the swing center of; the pawl 32 can be adjusted to a desired
15 posiUon wlthin a certaln rsnge, and thus the meshing state between
said pawl 32 and its ratchet 31 can be ad~usted. Therefore, according
to this construction, by first assembling the pawl 42 of the second
tilt locking mechanism 40 and, after meshing said pawl 42 with its
ratchet 41, subsequently assembling the pawl 32 of the first tilt
20 locking mechanism 30 with its swing center properly ad~usted as
described above, the meshlng states of the pawis 32 and 42 relative to
the ratchets 31 and 41 respectively can be set correctly, irrespective
of the inevitable manufacturing errors and assembling errors of the
varlous components d the two fflt mechanisms 30 and 40. And this
25 proper setting of the meshing states of the pawls 32 and 42 rehtive to
the ratchets 31 and 41 respectively is very materially aided by the
provision accordlng to the present inventlon of the certain degree of
play as explained above between the first release lever 33 of the first
tilt locking mechanism 30 and the coupiing member 38.
The present invention is not to be considered as limited in its
appl~cation to the type of steering device shown above, although that
is its most preferred application. Various other posslbilities are
a1so concelvable of. For example, it would be possible to apply the
35 constructlon, explained above, of providing a small amount of play in
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-- 22 --
the rotational dlrection between the first release lever 33 of the
first tilt locking mechanism 30 and the coupling member 38, for instead
provlding a smull smount of play in the rotational direction between
the coupling member 38 and the second release lever ~3 of the second
5 tilt locking mechsnism 40, thus allowing a very small but non zero
relstive movement amount between said coupling member 38 and said
second release lever 43 of said second tilt locking mechanism 40. This
would perform the same funcffon Or absorbing the inevitable
manufscturing errors present in the vsrious parts of the construction
10 and allowing smooth operstion. Alternatlvely, it would be possible to
construct the tilt locking mechanisms 30 and 40 in the reverse manner
to that shown, with the ratchets 31 and 41 instead assembled to the
main fixing bracket 32, and with the pawls 32 and 42 rotatably mounte<i
to the rotatable bracket 25. In either csse, it will be clear to one
15 oi' ordinary skill in the art, based upon the descriptions contaLned in
this specification, that the same advantages as accrued in the case of
the first preferred embodiment of the present invention described above
will be avallable.
The preænt invenUon can slso be applied to a tilt steerjng
column of a type disclosed in Japsnese Utility Model Pub]icst~on Seri~l
No. 57-53730 applled for by the assignee of the present patent
appl~cation. This type of steering column may not be provided with any
memory function and/or any telescopic iunction. For applying this
invention to a tilt steering column in which the upper steering column
tube is directly pivoted to the lower steering column tube, the ratchet
or ratchets may be assembled to either one of the tubes, and the pawl
or pawls may be assembled to the other one of the tubes. Therefore,
although the present invention has been shown and described in terms of
certain preferred embodiments thereof, and with reference to the
appended drawings, it should not be considered as being particularly
limited thereby. The details of any particular embodiment, or of the
drawlngs, could be varied without, in many cases, departing from the
ambit of the present invention. Accordingly, the scope of the present
invention is to be considered as being delimited, not by any particular
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perhsps entirely fortuitous details oE the disclosed preferred
embodiments, or Or the drawings, but solely by the le~itlmate snd
properly interpreted scope of the accompanying claims, which ~ollow.
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