Longitudinal locking mechanism for vehicle seat

A longitudinal locking mechanism in which a male lock member may be adjustably projected from a female lock member in the longitudinal direction thereof. The female lock member has a bellmouthed split end portion warped outwardly and radially relative to the central axis thereof. Such bellmouthed split end portion may be elastically closed by a slide ring for threaded engagement with the male lock member, so that a desired projection amount of the male lock member may be adjusted for locking purposes in a vehicle seat. The slide ring is biased in a direction to close the bellmouthed split end portion of female lock member, and may be drawn by an operation lever, via an actuation element, in a direction away from that bellmouthed split end portion so as to release the threaded enagement between the male and female lock members.

BACKGROUND OF INVENTION 
1. Field of the Invention 
The present invention relates to a longitudinal locking mechanism for use 
in a vehicle seat. The longitudinal locking mechanism has a rod slidably 
inserted in a cylindrical body along the longitudinal direction thereof 
such as to permit the rod to be adjustably locked in a selected length for 
adjustment of a movable element in the vehicle seat. 
2. Description of Prior Art 
As widely known in a seat for vehicles, a longitudinal locking mechanism is 
employed as one of mechanical lock devices to lock and unlock a movable 
element in the seat such as a reclining device or seat height adjuster. 
Hitherto, most of such longitudinal locking mechanism has been of the 
construction wherein a rod is slidably accommodated in a cylindrical body 
in the longitudinal direction thereof, with a torsion spring being wound 
around the rod. According to this conventional locking mechanism, the rod 
is throttled strongly by the torsion spring and retained in a locked state 
due to a friction therebetween, thereby projecting its free end portion in 
a selected length from the cylindrical body. The rod may be released from 
the locked state by forcibly reducing the throttling force of torsion 
spring and permitted to be projected from and withdrawn into the 
cylindrical body as desired. In that way, the free end portion of the rod 
may be adjusted in length for applications to adjustments of movable 
elements in the seat. 
The locking strength in this conventional torsion spring locking mechanism 
is dependent only upon a frictional force between the rod and torsion 
spring. It has been found that errors in diameter between the torsion 
spring and rod, or variation of spring force in each torsion spring, which 
are apt to occur during assemblage, will inevitably result in undesired 
variations of frictional force between the rod and torsion spring in each 
of the locking mechanisms and therefore there will be no constant quality 
and no reliability of locking performances in this sort of conventional 
longitudinal locking mechanism. In other words, assembling such 
torsion-spring longitudinal locking mechanism requires a high precision in 
maintaining a constant quality of the torsion spring and rod in terms of 
their relative dimensions and requires a high expertise in assembling them 
together, with the result that a more intricate design of structure or 
troublesome labor is inevitably demanded on the part of workers, which 
incurs much costs involved. Moreover, normally, the unlocking operation in 
this mechanism requires a cocentric rotary action about the torsion spring 
to reduce the throttling force of the same spring to the rod, and such 
rotary action is made in a directin transversing the width-wise direction 
of seat, giving uneasy and hard fealing to a user as compared with a 
longitudinal drawing or pressing action. 
SUMMARY OF THE INVENTION 
In view of the above-stated drawbacks, it is a primary purpose of the 
present invention to provide an improved longitudinal locking mechanism 
which permits for easy and positive locking operation in a vehicle seat 
with a simplified structure. 
In order to achieve such purpose, the longitudinal locking mechanism, in 
accordance with the present invention, basically comprises: 
a tubular base member; 
a male lock means having an external threaded portion, which male lock 
means is so slidably accommodated in the tubular base member as to project 
therefrom and withdraw thereinto in a longitudinal direction thereof; 
a female lock means connected to the tubular base member, the female lock 
means having a bellmouthed split end portion in which a plurality of split 
sections are so defined as to be elastically warped outwardly and radially 
relative to a central axis of the female lock means, wherein inwardly 
threaded regions are defined in those plurality of split sections, 
respectively; 
a slide means which is so slidably attached about the female lock means as 
to be movable along a longitudinal direction thereof for warping the 
plural split sections of female lock means in a direction towards and away 
from a central axis of the female lock means; 
an operation lever; and 
an actuation means operatively connected to the slide means and operation 
lever, which actuation means is operable via the operation lever to cause 
the slide means to be slid along the female lock means in the longitudinal 
direction thereof so as to forcibly warp the plural split sections of 
female lock means inwardly towards the central axis of same female lock 
means to thereby bring the internally threaded regions of split sections 
to a meshed engagement with a part of the externally threaded portion of 
male lock means. 
Accordingly, the female lock means provides an embracingly meshed 
engagement with and about the male lock means, which insures to lock the 
male lock means at a selected point relative to the female lock means, in 
a simplified structure, thereby enabling a user to smoothly adjust the 
amount of projection of male lock means, with an unchanged locking 
quality. 
The male lock means is so biased by a biasing said actuation means includes 
a spring for so biasing the slide means as to forcibly warp the plural 
split sections of female lock means inwardly towards the central axis of 
female lock means. 
Preferably, the female lock means may comprise a generally horn shape which 
is formed from a tubular metallic material such that the bellmouthed split 
end portion thereof is given a certain elastic property. 
As an essential mode in the present invention, the actuation means 
comprises a compression spring interposed between the slide means and 
tubular base member, the compression spring biasing the slide means such 
as to forcibly warp the split sections of female lock means inwardly 
towards the central axis of said female lock means and a drawing means for 
drawing the slide means against a biasing force of the compression spring 
in a direction away from the slide means, the drawing means being 
connected to the slide means and operation lever. 
Accordingly, the drawing means permits the operation lever to be moved in a 
longitudinal direction, which avoids such concentric rotary action found 
in the prior art. Preferably, the foregoing drawing means may comprise a 
guide frame rotatably provided at said tubular base member, with such an 
arrangement that the guide frame may be rotated relative to the tubular 
base member by the operation lever in a direction to draw the slide means 
away from the split sections of female lock means, against the biasing 
force of compression spring. 
Preferably, the foregoing guide frame may be formed in a manner surrounding 
both female lock means and tubular lock member and having a center of 
rotation above the tubular lock member, and further be formed with a pair 
of holes in the respective two lateral sides thereof such as to be 
disposed symmetrically to and on the opposite sides of both female lock 
means and tubular base member. The slide means may be provided with a pair 
of spaced-apart engagement pins projecting in a direction opposite to each 
other, and those two engagement pins are fitted in the two holes of guide 
frame, respectively. 
As one exemplary mode, the guide frame may be of a generally rectangular 
shape, and an upper side of such guide frame be connected rotatably to a 
part of a bracket fixed on the upper side of the tubular base member, 
wherein such part of bracket corresponds to the foregoing center of 
rotation. Further, th foregoing two holes be formed in the respective two 
lateral sides of guide frame, and the operation lever be fixed to one of 
the two lateral sides of guide frame. 
As another alternative exemplary mode, the guide frame may be provided 
separately from the tubular base member, having a center of rotation 
defined therein, and the drawing means may further include a pair of cable 
wires disposed symmetrically relative to and alongside both female lock 
means and tubular base member, with such an arrangement that first end 
portions respectively of the two cable wires are fixed to two lateral 
sides of the slide means and slidably supported on said tubular member, 
while second end portions respectively of the two cable wires are both 
connected to the guide frame.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
Now, FIGS. 1 through 8 illustrate preferred constructions of longitudinal 
locking mechanisms by way of example in accordance with the present 
invention. 
All through the embodiments in FIGS. 1 to 8, a basic construction of 
longitudinal locking mechanism commonly contemplated in the present 
invention is comprised of: 
(a) a tubular base member (12 or 12'); 
(b) a tubular female lock means (A) having a bell-mouthed split end portion 
(22a) in which an internally threaded region (26) is formed; 
(c) a columnar male lock means (B) slidably inserted in the tubular female 
lock means (A), which has an externally threaded region (26) formed 
partway and circumferentially thereof and a biasing spring (16) provided 
for biasing the male lock means in a direction to project from the female 
lock means (A); 
(d) a slide ring means (C) slidably attached about the tubular female lock 
means (A) for closing and opening the bellmouthed split end portion (22a); 
and 
(e) an actuator means (D) arranged between the slide ring means (C) and an 
operation lever (36). 
This basic structure in accordance with the present invention is embodied 
commonly in one mode shown in FIGS. 1 to 3, in another alternative mode 
shown in FIGS. 5 and 6 and in still another alternative mode shown in 
FIGS. 7 and 8, with some modifications and additions permissible within 
the gist of the present invention. Of course, those modes are not 
limitative, and other further alternative modes may be adopted in various 
ways within the gist of the present invention. 
Firstly, reference is made to the first mode of longitudinal locking 
mechanism (10) shown in FIGS. 1 to 3. In the present mode, as the 
foregoing female and male lock means (A) (B), there are provided a tubular 
female lock member (22) having three-split bellmouthed free end portion 
(22a) and a columnar male lock rod member (14) having an externally 
threaded portion (20) formed in the forward half portion thereof. 
The female lock member (22) is formed from a metallic tubular material in 
the illustrated generally horn shape, as by quench hardening, such that 
the forward bellmouthed end portion (22a) thereof is so cut in the 
longitudinal direction as to form three equidistant elongated splits (24) 
therein, thus providing three divergent split sections (22aE) warped 
outwardly and radially relative to a central axis of the straight tubular 
section thereof. Each of the three divergent split sections (22aE) has an 
internally threaded region (26) formed in the inner surface thereof. The 
female lock member (22) is further formed with an externally threaded 
region (22b) at the backward end thereof. A tubular base member (12) is 
formed with an internally threaded portion (12a-1) in the forward end 
thereof. Thus, the female lock member (22) is connected to the tubular 
base member (12) by threadedly engaging the externally threaded portion 
(22b) of the former (22) with the internally threaded portion (12a-1) of 
the latter (12). 
As the slide ring means (C), a slide ring (28) is provided, which has a 
divergently sloped internal annular region (28a) formed in the forward end 
thereof. This slide ring (28) is slidably fitted on and about the straight 
tubular section of the female lock member (22), such that the internal 
annular region (28a) of slide ring (28) is to be fit contacted with a 
divergent root area of the bellmouthed end portion (22a) of female lock 
member (22) for the purpose of causing the three divergent split sections 
(22aE) to move toward one another from the radially warped state, as will 
be explained later. 
The male lock rod member (14) is slidably accommodated in both female lock 
and base members (22) (12) which are connected together as stated above in 
the manner shown in FIG. 2, with its backward end (14b) being abutted via 
a flange (19) against a biasing spring (16) sandwiched between the flange 
(19) and a support rod (18). Hence, the male lock rod member (14) is 
biased by the spring (16) in a direction forwardly of both female and base 
members (22) (12) so as to project both forward end (14a) and externally 
threaded portion (20) thereof from the bellmouthed end portion (22a). 
Designation (56) denotes a support ring member which is fixed on the inner 
surface of tubular base member (12), through which support ring (56), the 
male lock rod member (14) is slidably supported. With the structure thus 
described, a basic unit of male and female lock mechanism (12, 14, 16, 22, 
28) is established. 
On the other hand, the actuation means (D) in this mode (10) is embodied by 
comprising: a pair of spaced-apart first and second ringed flanges (33) 
(32); a compression spring (30); a guide frame (44); and a support bracket 
(46). 
Turning to view of FIG. 2, the first ringed flange (33) is fixed on and 
about the outer surface of the slide ring (28), while the second ringed 
flange (32) is fixed on and about the forward end part (12a) of tubular 
base member (12), such that the two flanges (33) (32) face toward each 
other for retaining the compression spring (30) therebetween. As 
understandable from FIGS. 1 and 2, the first ringed flange (33) is formed 
with a pair of lugs (33a) on which two engagement pins (33b) are formed, 
respectively, and thus it is to be understood, though not shown clearly, 
that a pair of engagement pins (33b) are arranged on the opposite sides of 
the slide ring (28), projecting outwardly and symmetrically relative 
thereto. 
The guide frame (44) is shown in FIG. 1 to be formed in a rectangular shape 
having a lower frame section (44c), two lateral frame sections (44b) (44b) 
and two upper connecting lugs (44a). A pair of connecting holes (42) (42) 
are formed midway in the respective two lateral frame sections (44b) (44b) 
in a mutually faced relationship. The operation lever (36) is fixed to one 
of the two lateral frame sections (44b). As shown in FIG. 1, the guide 
frame (44) is mounted on the above-described unit of male and female lock 
mechanism (12, 14, 16, 24, 28) such that the two engagement pins (33b) of 
first ringed flange (33) are slidably engaged in the two connecting holes 
(42) (42) of guide frame (44), respectively, and that the two connecting 
lugs (44a) of guide frame (44) are rotatably connected via a pin (48) to 
one end (46a) of support bracket (46) fixed on the tubular base member 
(12). 
As constructed above, therefore, when in no use, the slide ring (28) is 
biased by the compression spring (30) forwardly along the longitudinal 
direction of the female lock member (22), so that the divergently sloped 
internal annular region (28a) of slide ring (28) is normally biased to a 
close contact with the divergent root area of bellmouthed split end 
portion (22a) of female lock member (22), whereupon, all the three 
divergent split sections (22aE) are biased toward one another, thereby 
forcibly bringing their respective internally threaded region (26) in a 
full meshed engagement with a part of the externally threaded portion (20) 
of male lock rod member (14). Namely, the male lock rod member (14) is 
placed in a locked state and projects in a given length, with respect to 
the female lock member (22). At the same time, under the forward biasing 
force of the compression spring (30), the guide frame (44) and operation 
lever (36) are normally biased to the upright and horizontal non-use 
positions, respectively, as indicated by the two-dot chain lines in FIG. 
2. 
Conversely, referring to FIG. 3, when it is desired to adjust the 
projection amount of male lock rod member (14) from the female lock member 
(22), the operation lever (36) may be raised, overcoming the biasing force 
of spring (30), relative to the pin (48) at the support bracket (46), 
which will cause simultaneous rotation of the guide frame (44) about the 
same pin (48) in the upward direction. With such rotation of guide frame 
(44), the two guide holes (42) are displaced in the backward direction 
relative to the female lock member (22), i.e. in a direction opposite to 
the forward biasing direction of the compression spring (30), and 
therefore, both two engagement pins (33b) engaged in the respective those 
two guide holes (42) are also displaced together with the guide frame 
(44), causing simultaneous backward sliding motion of the slide ring (28) 
along the female lock member (22) away from the bellmouthed end portion 
(22a). As a result, the three divergent split sections (28aE) are opened 
to the radially warped initial position as shown in FIG. 3, due to their 
elastic recovery nature, whereby the externally threaded portion (20) of 
male lock rod member (14) is released from the meshed engagement with the 
internally threaded regions (26) of those three split sections (22aE). At 
this moment, the male lock rod member (14) is allowed to be projected 
forwardly from the male lock member (24) by the biasing force of spring 
(16). Then, a user should lower the operation lever (36) to cause the 
slide ring (28), via those associated actuation elements (44, 33b, 33, 
30), to slide forwardly along the female lock member (22) to close the 
three split sections (22aE), thereby effecting a meshed engagement of the 
internally threaded region (26) with a selected part of the externally 
threaded portion (20) so as to set a desired projection amount of the male 
lock rod member (14). Accordingly, for example, in the case where the 
present lock mechanism (10) is used in a reclining device of vehicle seat 
as shown in FIG. 4, a seat back (SB) may be adjusted in reclining angle 
relative to a seat cushion (SC) by adjusting the projection amount of male 
lock rod member (14). In this case, the lock mechanism (10) is fixed at 
its support rod (18) to a seat cushion frame (F), and pivotally connected 
at its forward end part (14a) to the lower end of upper arm (54) via a pin 
(P2). Thus, the projection and withdrawal of the male lock rod member (14) 
produces the fore-and-aft inclination of the seat back (SB) about a pin 
(P1) fixed to frame (15) of seat cushion (SC). 
FIGS. 5 and 6 show a second mode of longitudinal locking mechanism (110). 
This mode is basically identical in structure and mechanical principle to 
the foregoing first mode (10) in terms of the male and female lock means 
(A) (B), tubular base member (12) and slide ring means (C), except that 
some modifications are made to the actuation means (D). Hence, specific 
explanations are deleted with regard to those basically identical four 
means (A) (B) (C) (12 or 12') to those of the first mode (10) for the sake 
of simplicity in description. 
Namely, as understandable from FIG. 6, an actuation means (D) according to 
the present mode (110) differs from that of the first mode (10) in that: 
(i) A pair of first and second ringed flanges (28'b) (32') are provided as 
an equivalent to those (33) (32) of the first mode (10). They are provided 
at the backward end of slide ring (C or 28') and the forward end of 
tubular base member (12'), respectively, with the compression spring (30) 
retained between the two flanges (28'b) (32'), as likewise in the first 
mode (10). 
(ii) A pair of first and second L-shaped brackets (33') (33") and a pair of 
cable wires (66) (66) are arranged around the compression spring (30), 
while a guide frame (44') is connected to both bifurcated cable wires (66) 
(66), as one of the actuation means (D) equivalent in functions to the 
support bracket (46) and guide frame (44) of the first mode (10). 
The above-noted actuation means (D) in this particular mode (110) are 
therefore an alternative to the previously described actuation means (D) 
of the first mode (10) for the common purpose of causing the bellmouthed 
split end portion (22a) of female lock member (22) to be opened and closed 
with respect to the male lock member (14). Specifically, according to the 
illustrations in FIGS. 5 and 6, the first ringed flange (28'b) is formed 
in a recessed manner in and along the backward end of slide ring (28'), 
and the second ringed flange (32') is threadedly secured in the forward 
end of the tubular base member (12). Strictly stated, the slide ring (28') 
is of a great thickness relative to that of the slide ring (28) of the 
first mode (10), but basically identical in shape and structure thereto. 
Both first and second ringed flanges (28'b) (32') have an inner diameter 
slightly greater than the outer diameter of compression spring (30) for 
the purpose of receiving and retaining the compression spring (30) 
therebetween. The two first L-shaped brackets (33') (33') are fixed on the 
respective upper and lower sides of slide ring (28'), and likewise, the 
two second L-shaped brackets (33") (33") are fixed on the respective upper 
and lower sides of tubular base member (12'), such that the first and 
second L-shaped brackets (33') (33") face toward one another as best seen 
in FIG. 6. The spherical securing ends (66aE) respectively of the 
bifurcated cable wires (66) (66) are each secured in the notches of first 
and second L-shaped brackets (33') (33'), respectively, whereas on the 
other hand, the bifurcated cable bodies (66) (66) are secured in the 
notches of first and second L-shaped brackets (33') (33"). 
The bifurcated two cable wires (66) (66) are connected in a unitary one 
cable manner to the lower end of the guide frame (44'); namely, the ringed 
end of wire (66a) of such unitary one cable body is securely fitted to a 
pin (48') fixed on the lower end of guide frame (44'). As shown, the 
operation lever (36) is fixed on the upper end of guide frame (44'). A 
rotation hole (44'a) is formed midway in the guide frame (44'). Although 
not shown, the guide frame (44') is rotatably supported, at the hole 
(44'a) thereof, on a support shaft fixed on the frame (F), as can be seen 
in FIG. 4, for example. 
The backward end (14b) of male lock member (14) is formed with an extension 
(14bE) having a small diameter relative thereto. As shown, a ringed flange 
(19') equivalent to that (19) of the first mode (10) is fitted about that 
extension (14bE) and fixed thereto by means of a stopper pin (19'a) 
penetrating through both hole (h) of the extension (14bE) and ringed 
flange (19'). 
According to the present second mode (110), when in no use, the slide ring 
(28') is biased by the compression spring (30) forwardly along the 
longitudinal direction of female lock member (22), thereby biasing the 
divergently sloped internal annular region (28'a) thereof to a close 
contact with the divergent root area of bellmouthed end portion (22a) of 
female lock member (22), so as to force all the three split sections 
(22aE) towards one another, whereby the internally threaded regions (26) 
of three split sections (22aE) are kept in a full meshed engagement with a 
part of the externally threaded portion (20) of male lock rod member (14). 
Also, under the biasing force of compression spring (30), both two cable 
wires (66a) (66a) are drawn forwardly with slide ring (28') between the 
first and second L-shaped brackets (33') (33"), which in turn draws the 
lower end of guide frame (44') in a direction to bias the operation lever 
(36) towards the horizontal non-use position as shown in FIG. 6. 
Conversely, when it is desired to adjust the projection amount of male lock 
rod member (14) from the female lock member (22), the operation lever (36) 
may be raised, overcoming the biasing force of spring (30), relative to 
the hole (44'a) of guide frame (44'), which will cause simultaneous 
rotation of the lower end of guide frame (44') about the same hole (44'a), 
as indicated by the arrows in FIG. 6. With such rotation of guide frame 
(44'), the bifurcated cable wires (66a) (66a) are drawn backwardly 
relative to the female lock member (22), i.e. in a direction opposite to 
the forward biasing direction of the compression spring (30), imparting 
thus a backward pulling force to both paired first brackets (33'), whereby 
the slide ring (28') integral with those brackets (33') is caused to slide 
along the female lock member (22) away from the bellmouthed end portion 
(22a). As a result, the three divergent split sections (28aE) are opened 
radially from the axis of male lock rod member (14), as seen in FIG. 3, 
due to their elastic recovery nature, so that the externally toothed 
portion (20) of male lock rod member (14) is released from the meshed 
engagement with the internally threaded regions (26) of those three split 
sections (28aE). At this moment, the male lock rod member (14) is allowed 
to be projected forwardly from the male lock member (24) by the biasing 
force of spring (16). Then, a user can lower the operation lever (36) so 
as to to effect meshed enagement between the male and female lock members 
(14) (22) and set a desired projection amount of the male lock rod member 
(14). It is appreciated in this second mode (110) that the symmetrical 
disposition of the paired cable wires (66) (66) relative to the slide ring 
(28') gives a uniform rectilinear drawing force to both slide ring (28') 
and compression spring (30) and that the operation lever (36) may be 
disposed anywhere separate from the locking mechanism for remote control 
operation. 
FIGS. 7 and 8 show a third alternative mode (111) which is a slight 
modification of the foregoing second mode (110) on the basis of the first 
mode (10). 
Namely, the present third mode of longitudinal locking mechanism (111) is 
basically identical in the male and female lock means (A) (B), slide ring 
means (C) and base member (12) to both first and second mode (110), except 
that a guide frame (44") is disposed coaxially of the body of locking 
mechanism, with the operation lever (36) connected directly to the guide 
frame (44"), as similar to the first mode (10), instead of the separate 
arrangement of the guide frame (44') and operation lever (36) from the 
locking mechanism suggested in the second mode (110). Hence, specific 
explanations are deleted with regard to those basically identical four 
means (A) (B) (C) (12 or 12') to those of the first and second modes (10) 
(110) for the sake of simplicity in description. 
According to the present mode (111), an actuation means (D) differs from 
the second mode (110) in that: 
(i) A ringed bracket (33") is secured about the slide ring (28"), as an 
equivalent to the paired first L-shaped brackets (33') of the second mode 
(110). 
(ii) A generally U-shaped guide frame (44") is provided as an equivalent to 
a flat plate of guide frame (44') of the second mode (110). 
(iii) A pair of separate wires (66') (66') are extended between the ringed 
bracket (33") and U-shaped guide frame (44") as an equivalent to the 
bifurcated cable wire (66) of the second mode (110). 
The above-noted actuation means (D) in this particular mode (111) are 
therefore an alternative to the previously described actuation means (D) 
of the second mode (110) for the common purpose of causing the bellmouthed 
split end portion (22a) of female lock member (22) to be opened and closed 
with respect to the male lock member (14). Specifically, according to the 
illustrations in FIGS. 7 and 8, the ringed flange (33") is secured about a 
slide ring (28") and retained by the protruded annular detent portion 
(28"b) of the same slide ring (28"). The forward end part (28"a) of slide 
ring (28") is formed in a bellmouthed fashion, as an equivalent to the 
divergently sloped internal annular regions (28a) (28'a) respectively of 
the two slide rings (28) (28') of first and second modes (10) (110), so as 
to fit contact the divergent root area of the bellmouthed end portion 
(22a) of female lock member (22). 
The generally U-shaped guide frame (44") is formed by a horizontal frame 
section (44"c) and a pair of first and second vertically extending lateral 
frame sections (44"a) (44"b), such that the second lateral frame section 
(44"b) extends upwardly longer than the first lateral frame section (44"a) 
and terminates in a hook end portion (44"d) extending backwardly of the 
tubular base member (12). The hook end portion (44"d) is connected via a 
hinge pin (44"e) to the operation lever (36), the hinge pin (44"e) 
penetrating rotatably through the frame (F) as in FIG. 4. As shown, the 
two spherical securing ends (66'e) of two separate wires (66') (66') are 
secured in the ringed flange (33"), while another ends of the same (66') 
(66') are secured in the two vertical extending lateral sections (44"a) 
(44"b), respectively. The tubular base member (12) is fixed via the shaft 
(18) to the frame (F). Designation (143) denotes a stopper pin on which 
the hook end portion (44"d) of guide frame (44") is abutted. This stopper 
pin (143) limits the clockwise rotation of the guide frame (44"), as 
viewed from FIG. 7, which is caused by the forward pulling force of the 
two wires (66') (66') produced from the forward biasing force of 
compression spring (30). 
Designation (144) denotes an auxiliary spring extended between the frame 
(F) and guide frame (44"). By means of this auxiliary spring (144), the 
guide frame (44") is given an additional biasing force in the clockwise 
direction relative to the hinge pin (44"e) and positively abutted against 
the pin (143) in the illustrated upright non-use state. 
In brief, when it is desired to adjust the projection amount of the male 
lock rod member (14) relative to the female lock member (22), a user 
should rotate upwards the operation lever (36) as indicated by the arrows 
in FIG. 7, which will cause simultaneous anticlockwise rotation of the 
guide frame (44") about the hinge pin (44"e) so that both lateral sections 
(44"a) (44"b) of guide frame (44") are displaced in the same anticlockwise 
direction to draw the two wires (66'). In response thereto, the slide ring 
(28") is slid backwardly along the female lock member (22), allowing the 
three divergent split sections (22aE) to be opened radially, with their 
elastic recovery nature, as in FIG. 3, for disengagement of the internally 
threaded regions (26) thereof from the externally threaded portion (20) of 
male lock rod member (14). All other operations should be done by the 
operation lever (36) in the same manner as described above in both first 
and second modes (10) (110) for locking and unlocking to attain a desired 
projection amount of the male lock rod member (14) from the female lock 
member (22). The present third mode (111) achieves the same effects with 
those of the second mode (110) that a uniform rectilinear drawing force 
can be applied to both slide ring (28") and compression spring (30), in 
addition to the same structure as in the first mode that the operation 
lever (36) is directly connected to the guide frame (44). 
Of course, both second and third modes (110) (111) may be used in a 
reclining device as shown in FIG. 4, or used in other adjustment 
mechanisms in a vehicle seat. 
Accordingly, in all the modes (10) (110) (111), the female lock member (22) 
provides an embracingly meshed engagement with and about the male lock rod 
member (14), which insures to lock the male lock rod member (14) at a 
selected point relative to the female lock member (22), with an unchanged 
locking quality, and further a user can move the operation lever (36) in a 
longitudinal direction with respect to the seat (see FIG. 4) and smoothly 
adjust a desired amount of projection of the male lock rod member (14). 
While having described the present invention thus far, it should be 
understood that the invention is not limited to the illustrated 
embodiments, but other modifications, replacements and additions may be 
structurally and mechanically applied thereto without departing from the 
scopes of the appended claims. Naturally, it is free to adopt one of the 
first, second and third modes (10) (110) (111) or to only choose one of 
the three actuation means (D). Also, it is not limitative whether the 
operation lever (36) may be integral with the actuation means (D) or 
separate therefrom via a cable wire (66), and it is indeed possible to 
combine some parts of the three modes (10) (110) (111) together 
appropriately, depending on design requirements, within the gist of the 
present invention.