Pan-type vehicle seat back mounted to a reclining mechanism

A vehicle seat is disclosed in which the movable arm members of its reclining mechanism are mounted to reinforcing members provided inside a back frame of a pan-type structure. Bolts for fixing the movable arm members are not projected outside the back frame.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a vehicle seat, and more particularly to 
an automobile seat having an improved mounting structure for securing a 
movable arm member of a reclining mechanism to a back frame constituting a 
seat back. The present invention is advantageous in that it is safer as 
compared to conventional vehicle seats since bolts for fixing the movable 
arm member do not project beyond the outer surface of the back frame and 
also in that it can eliminate the possibility of damaging the outer 
peripheral surface of the back frame when the movable arm member is fixed 
to the back frame. 
2. Description of the Prior Art 
In conventional vehicle seats in which there is mounted a reclining 
mechanism between a seat cushion and a seat back so as to be able to 
incline the seat back, and the back frame of the seat back has a pan-type 
structure formed of synthetic resin or steel plate, as shown in FIG. 1(A), 
the back frame (1) includes a rear surface (2) which is generally 
rectangular. On the periphery of the rear surface (2) there are provided 
upper, lower, right and left walls (4a), (4b), (4c) and (4d) and also at 
the convenient positions of the rear surface (2) there are arranged 
reinforcing ribs (5a), (5b) which extend longitudinally and transversely, 
respectively. 
Also, with the end portions (6a) of the reclining mechanisms (6) being 
respectively fixed to a cushion frame, a pair of movable arm members each 
on a free hinge (not shown) are respectively abutted against the inner 
surfaces of the right and left walls (4c) and (4d) through grooves (7),(7) 
cut in the lower wall (4b) of the back frame (1) in a mutually opposing 
relation, and thereafter the movable arm members (6b) are respectively 
fastened to the right and left walls (4c), (4d) by means of bolts (9) and 
nuts (10) to provide an assembly. 
However, when the movable arm members (6b) of the reclining mechanism (6) 
are assembled to the back frame (1) in the above described manner, as 
shown more clearly in FIG. 1(B), it is necessary to tighten the bolts (9) 
from the side of the outer surfaces of the right and left wall (4c) and 
(4d), which involves several disadvantages. For example, there is a 
possibility that the outer surface of the back frame (1) may be damaged by 
the tip end of a tool during the assembling operation. Also, the bolts may 
be dangerous to a seat occupant because the head portions of the bolts (9) 
project beyond the outer surfaces of the right and left walls (4c) and 
(4d). Moreover, the bolts used must be surface-treated with some high 
quality processes, such as a chrome plating so that the aesthetic 
appearance of the seat will not be impaired. Such processes however result 
in increased costs. 
SUMMARY OF THE INVENTION 
Thus, the present invention aims at overcoming the drawbacks mentioned 
above which have been present in the prior art vehicles seats. According 
to the invention, there are disclosed herein four embodiments each having 
an improved mounting structure for securing a pair of movable arm members 
of a reclining mechanism to a back frame; each of the embodiments is safer 
as compared to conventional vehicle seats in that bolts used for fixing 
the movable arm members to the back frame are not projected ouside the 
back frame and at the same time each embodiment can also eliminate the 
possibility of the back frame being lowered in strength or being damaged 
due to the mounting of the movable arm members to the back frame. 
In brief, the above and other objects, features and advantages of the 
present invention are attained by providing a vehicle seat in which the 
movable arm members of its reclining mechanism are mounted to reinforcing 
members provided inside a back frame of a pan-type structure. Thus, with 
the present invention, the bolts for fixing the movable arm members are 
not projected outside the back frame, nor is it necessary to drill holes 
for securing the movable arm members in the peripheral walls of the back 
frame unlike in the above described prior art, which can eliminate the 
possibility of the back frame being degraded in strength or being damaged. 
In addition, the reinforcing members provided inside the back frame are 
reinforcing ribs each of which is formed to have an enlarged thickness as 
as to enhance its reinforcing efftect.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
We will now describe several embodiments according to the present invention 
in detail with reference to FIGS. 2-6. The same parts as illustrated in 
both FIGS. 1(A) and 1(B) are designated by the same numerals in FIGS. 1(A) 
and 1(B), and the repeated description of them is omitted. 
According to the present invention, a pair of reclining mechanisms (6) and 
a pair of movable arm members (6b), each of which is included in one of 
the reclining mechanisms and is mounted on a free hinge (not shown), are 
positioned outside reinforcing ribs (5a) in their respective opposing 
relations, and thereafter they are fastened and assembled together by 
bolts (9) and nuts (10). FIGS. 3 and 4 illustrate two embodiments of thus 
assembled portions respectively. In a first embodiment shown in FIG. 3, 
each of the movable arm members (6b) is fixed to the respective 
reinforcing ribs (5a). For enhancing the reinforcing effect, the portions 
of the reinforcing ribs (5a) which serve to fix the movable arm members 
may be formed to have an enlarged thickness (11), as shown by a two-dot 
chain line in FIGS. 3 and 4. 
Thus, with the above mentioned arrangements of the invention, several 
practical effects can be obtained; for example, safety is ensured by the 
fact that the bolts for fixing the movable arms of the reclining 
mechanisms are never projected outside a back frame (1); it is not 
necessary to use decorative bolts for the purpose of the aesthetic 
appearance of the seat; since the assembling operation of the movable arm 
members to the back frame is carried out inside the back frame, there is 
no possibility that the outer peripheral surfaces of the back frame are 
damaged; and, a fine surface treating process which is rather expensive 
can be eliminated, resulting in decrease in the cost. 
FIG. 4 illustrates a second embodiment of the present invention in which 
the right and left reinforcing ribs (5a) are arranged to extend 
continuously to the lower wall (4b) of the back frame (2), a groove (7) is 
cut between the right and left walls (4c) and (4d), and the reinforcing 
ribs (5a) and the movable arm members (6b) of the reclining mechanisms (6) 
are fixed to the reinforcing ribs (5a). In this embodiment, similarly as 
in the embodiment shown in FIG. 3, the thickened portions (11) may be 
provided in the regions of the reinforcing ribs (5a) where the ribs fix 
the movable arm members thereto, so that an enhanced reinforcement can be 
attained. 
FIG. 5 illustrates a third embodiment of the present invention, in which 
each of the movable arm members (6b) of the reclining mechanisms (6) is 
formed to be bent at right angles, a lower, laterally extending 
reinforcing rib (5b) is provided with an enlarged or thickened portion 
(11), and both of the arm member and the rib are fixed together by bolts 
(9) and nuts (10). 
FIG. 6 illustrates a fourth embodiment of the present invention, wherein 
each of the movable arm members (6b) is provided at its one region with a 
step portion (6c), the movable arm member (6b) is inserted through a 
projection (5c) integrally formed on the rear surface (2) of the back 
frame (1) by means of a groove (5d) in this projection (5c) while the step 
portion (6c) is abutted against the projection (5c) to hold and position 
the movable arm member, whereby the movable arm member (6b) can be easily 
mounted onto the reinforcing rib (5a). 
Although in each of the above mentioned embodiments the movable arms of the 
reclining mechanism are mounted onto the reinforcing members such as 
reinforcing ribs or reinforcing frames, means for securing and fastening 
the movable arm members within the upper, lower, right and left walls 
(4a), (4b), (4c) and (4d) of the back frame (1) may also be provided 
integrally in the reinforcing ribs, reinforcing frames, or upper, lower, 
right and left walls. 
It should be also understood that other various changes or modifications of 
the parts are possible within the scope of the invention. When the back 
frame is cantilevered, a movable arm member on a free hinge can also be 
mounted in the same manner as described above, and thus its explanation 
may be omitted here. 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of the present invention, and, without 
departing from the spirit and scope thereof, can make various changes and 
modifications of the invention to adapt it to various usages and 
conditions.