Vehicle seat

A seat for vehicles is provided with a pivotable seat back and a seat belt system including a seat belt, a belt roll-up device, and a belt deflector mounted on the seat back. A locking device triggerable in the event of a collision is provided for securing the seat back to the vehicle body. To create a highly stable locking device without having parts projecting therefrom when the seat back is folded, the locking device has a locking pin that is displaceable crosswise with respect to the vehicle, the pin cooperating with a hole located in the side wall of the body and urged by a tensioned drive spring in the direction of the hole, and a locking unit which secures the locking pin in its basic position against axial displacement. The locking unit is coupled to a section of the seat belt located between the belt roll-up device and the belt deflector in such fashion that it releases the locking pin as a result of a pull that acts when the belt pull-out lock on the seat belt is active.

BACKGROUND AND SUMMARY OF THE INVENTION 
The invention relates to a seat for vehicles, especially automobiles, of 
the type including a seat cushion, a seat back pivotally mounted on the 
seat cushion for folding movement, a passenger restraining seat belt 
system, and a seat back locking system operable in dependence on the seat 
belt system operation. 
In a known seat of this type (German Patent Document DE 29 23 550 A1) the 
locking device has a transfer lever and a locking lever, each of which is 
mounted non-rotatably by one lever end on a pivot axis that is rotatably 
mounted in the seat back and extends in the transverse direction of the 
vehicle. At the other lever end of the transfer lever, a seat belt 
deflector is mounted extending at right angles from said lever, and the 
other lever end of the locking lever has a locking pin which can enter a 
locking hole in a locking track mounted on the side wall of the body. A 
retaining spring that engages the locking lever normally pivots the 
locking lever away from the locking track and thus prevents the locking 
pin from dropping into the locking hole. In a collision, the transfer 
lever is pivoted forward by the tension of the belt against the belt 
deflector, so that the locking lever is pivoted upward against the 
restoring force of the retaining spring on the pivot axis, and the locking 
pin drops into the locking hole. As a result, the restraining forces of 
the belt are conducted directly into the vehicle body, and excessive 
stress on the seat back frame does not develop. In order to ensure the 
function of the locking device even in different positions of the seat 
back when inclined at an angle to the vertical, a plurality of locking 
holes is arranged sequentially in the locking track, with one locking hole 
being associated with each of the angle adjustment positions for the seat 
back. 
When such seats are used as rear seats, in station wagons for example, the 
seat backs are made to fold so that when the rear seats are not occupied, 
by folding the seat back onto the seat cushion and possibly by folding the 
seat cushion against the back of the front seat, the size of the cargo bay 
of the vehicle can be increased. In the case of front seats of two-door 
vehicles, the seat backs are likewise mounted so they can fold onto the 
seat cushions of the front seats in order to provide access to the rear 
seats after the seat backs have been folded forward. In such folding seat 
backs, the lever handle of the locking device projecting laterally from 
the seat back with its transversely extending locking pin would not only 
collide with the side panel of the body, the arm rest on the door, etc. 
but also could cause injury if handled negligently by the passenger. 
An object of the invention, in a seat of the type referred to above is to 
improve the locking device that operates in a collision in such fashion 
that firstly a reliable guidance of the belt forces into the vehicle body 
in the event of a collision is ensured, and secondly unimpeded folding of 
the seat back is ensured without the risk of injury to the operator when 
the seat is unoccupied. 
This object is achieved in preferred embodiments of the invention by 
providing an arrangement with an axially displaceable locking pin in the 
seat back which is selectively released in dependence on the forces on the 
seat belt to thereby lockingly engage in an opening in an adjacent vehicle 
side body part. 
The seat according to the invention has the advantage that the entire 
locking device is integrated into the seat back and is activated only upon 
the actuation of the locking device in the event of a collision or during 
extremely hard braking, in other words, when the seat belt system for 
restraining the vehicle occupant is activated by exceeding a certain value 
of vehicle deceleration. The locking pin then projects further from the 
seat back and a highly stable collision-proof connection of the seat back 
to the vehicle body is achieved. The actuation of the locking device 
assumes that the seat is occupied and the seat belt has been put on by the 
vehicle occupant. 
To prevent the seat back from folding over when the seat is unoccupied, an 
additional conventional lock can be provided between the seat back and the 
vehicle body which must be released manually when folding the seat back. 
Such a lock however can be made very easily and economically, since in the 
event of a collision it must accept only slight forces that depend on the 
weight of the seat back. 
Other objects, advantages and novel features of the present invention will 
become apparent from the following detailed description of the invention 
when considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
The vehicle seat for an automobile shown in section in a side view in FIG. 
1 in known fashion has a seat cushion 10 and a back 11 which, as is not 
shown here in greater detail, is mounted on seat cushion 10 to pivot 
around a pivot axis that extends transversely with respect to the vehicle 
and is foldable at its front onto the surface of the seat cushion. Seat 
back 11 has a seat back frame 12 and a seat back cushion 13 that rests on 
an inner spring mounted inside seat back frame 12 (not shown here) and is 
covered by a cushion that also conceals the back of seat back frame 12. 
Seat back frame 12 consists of an upper cross tube 14, a lower cross tube 
15, and two side pillars 16 that connect the two cross tubes 14, 15 with 
one another, with only the left side pillar 16 being shown in the figures 
in the drawing. 
The vehicle seat has associated with it a seat belt system 17 for 
restraining a vehicle occupant sitting on the seat, said system in known 
fashion having a belt roll-up mechanism with a belt pull-out lock that 
acts in the event of a collision, the so-called retractor 18, a seat belt 
19 that can be pulled out of retractor 18, and a buckle, not shown here, 
that is anchored to the vehicle floor and into which in known fashion a 
lock tongue mounted on seat belt 19 is inserted after the vehicle occupant 
puts on seat belt 19. Retractor 18 is fastened by a tab 20 to bottom cross 
tube 15 of seat back frame 12, and seat belt 19 is pulled out of retractor 
18 and guided over a belt deflector 21 attached to seat back 12 above the 
shoulder of the vehicle occupant, and runs from there across the chest of 
the vehicle occupant. 
To form belt deflector 21, side pillar 16 of seat back frame 12 which is 
next to the body side wall indicated by 22 in FIGS. 1 and 2, in this case 
left side pillar 16, projects beyond the upper edge of seat back cushion 
13 and has on its extension 161 a cap 23 that extends up to seat back 
cushion 13, in which belt deflector 21 is formed as a cross rib 24. As can 
be seen most clearly in FIG. 4, seat belt 19 coming from retractor 18 runs 
from below into cap 23, rests on a guide surface 25 formed in cap 23 that 
abuts the back of extension 161 of side pillar 16, and passes through an 
opening 26 provided in the front of cap 23 to the front of seat back 11. 
Seat belt 19, before entering cap is guided over a sliding section 27 of a 
locking device 28 that will be described in greater detail below, with 
sliding section 27 being arranged so that the part 191 of seat belt 16 
that extends between retractor 18 and belt deflector 21 is bent at an 
obtuse angle in the vicinity of sliding section 27, in other words, the 
part of belt section 191 that extends from retractor 18 to sliding section 
27 forms, with the part of belt section 191 that extends from sliding 
section 27 to belt deflector 21, an obtuse angle in which sliding section 
27 is located. 
Locking device 28 serves, in the event of a vehicle accident or during an 
especially hard brake application, in other words when the belt pull-out 
lock in retractor 18 of seat belt system 17 is operative and the vehicle 
occupant is restrained in the seat by seat belt 19, to secure seat back 11 
to the vehicle body and thus to conduct the restraining forces of seat 
belt system 17 that act on seat back 12 directly into the vehicle body. 
For this purpose, locking device 28 has a locking pin 29 which is 
displaceable axially in seat back 12 in the transverse direction with 
respect to body side wall 22, a hole located in body side wall 22 (FIGS. 1 
and 2) for receiving the free end of locking pin 29, a drive spring 31 
that urges locking pin 29, said spring pushing locking pin 29 in the 
direction of hole 30 when released, and a locking unit 32 that secures 
locking pin 29 in its basic position when drive spring 31 is tensioned, in 
which position locking pin 29 is out of engagement with hole 30. Locking 
unit 32 is coupled to belt section 191 of seat belt 19 that runs between 
retractor 18 and belt deflector 21 in seat back 12 in such fashion that 
when the belt pull-out lock on retractor 18 is operative as a result of a 
pull 33 acting on seat belt 19 (FIGS. 1 and 4), locking pin 29 is released 
so that it can be displaced axially by drive spring 31 and enter hole 30. 
As is evident from FIGS. 2 and 3, locking pin 29 is guided axially 
displaceably in a guide sleeve 34 fastened in seat back 11, specifically 
in left side pillar 16 of vehicle frame 12. Drive spring 31 is designed as 
a compression spring that fits in guide sleeve 34 and at one end abuts one 
end of locking pin 29 and at the other end abuts guide sleeve 34. Guide 
sleeve 34 has a recess 35 that extends over a portion of its 
circumference, the axial width of said recess being slightly larger than 
the thickness of a locking member 36 of locking unit 32 so that locking 
member 36 can pass through recess 35 into the interior of guide sleeve 34. 
On locking pin 29, at a short distance from its end urged by drive spring 
31, a circumferential locking groove 37 is provided whose axial width is 
likewise slightly larger than the thickness of locking member 36. Recess 
35 and locking groove 37 are arranged relative to one another in space 
such that in the basic position of locking pin 29 in which the pin urged 
by drive spring 31 is free of hole 30 in body side wall 22, they lie in 
the same cross-sectional plane as locking pin 26 and guide sleeve 34, so 
that locking member 36 of locking unit 32 can fall through recess 35 into 
locking groove 37 and can secure locking pin 29 in its basic position 
against axial displacement. 
The locking unit 32 which is coupled to seat belt 19 to be triggered has an 
angle lever 38 with a long leg 381 and a short leg 382 extending therefrom 
at right angles. Angle lever 38 is rotatably mounted on upper cross tube 
14 of seat back frame 12. A torsion spring 39 slid onto cross tube 14 has 
one leg 391 abutting side pillar 16 and the other leg 392 abutting long 
leg 381 of angle lever 38. Long leg 381 has on its free end, locking 
member 36 that is preferably formed on the end of long leg 381 itself, and 
the spring pretensioning of torsion spring 39 is directed so that it urges 
angle lever 38 in a rotational direction in which locking member 36 is 
pushed into locking groove 37 in locking pin 29. The short leg 382 of 
angle lever 38 on one end has the sliding section 27 already mentioned 
which, with locking pin 29 secured by locking unit 32 in its basic 
position, pushes against belt section 191 of seat belt 19 in such fashion 
that the obtuse angle described above is formed in belt section 191. As 
can be seen from FIG. 2, the width of sliding section 27 (looking in the 
direction crosswise of the seat back) is made larger than the width of 
seat belt 19 so that the latter rests securely on sliding section 27. The 
pretensioning of torsion spring 39 is designed so that with a normal pull 
33 on seat belt 19, as occurs when seat belt 19 is normally pulled out of 
retractor 18 when seat belt 19 is put on, the reaction force exerted by 
belt section 191 on sliding section 27 cannot rotate angle lever 38. It is 
only when seat belt system 17 responds to an extremely strong deceleration 
of the vehicle, in other words, when the belt pull-out lock in retractor 
18 is operative and hence pull 33 on seat belt 19 exceeds a certain value 
(4000N for example), that the reaction force exerted by seat belt 19 on 
sliding section 27 can overcome the spring force of torsion spring 39 and 
angle lever 38 is pivoted against the pretensioning of torsion spring 39 
(clockwise in FIG. 1) so that locking member 36 at the end of long leg 381 
is lifted out of locking groove 37 of locking pin 29. Locking pin 29 which 
is now free is pushed outward by the force of expanding compression spring 
31 in guide sleeve 34 and enters hole 30 in body side wall 22. The 
displacement travel of locking pin 29 is limited by stop 40 located at the 
bottom of hole 30. As a result, seat frame 12, and especially side pillar 
16 that supports belt deflector 21, is connected in a highly stable 
fashion with body side wall 22, and the retaining forces conducted by seat 
belt 19 through belt deflector 21 into the side pillar are conducted 
directly into the vehicle body. 
The unlocking of seat back 12 and body side wall 22 is performed manually, 
for which purpose locking pin 29 is pushed back into guide sleeve 34 until 
locking member 36 tensioned by torsion spring 39, which abuts in recess 35 
in guide sleeve 34 into an at the circumference of locking pin 29, snaps 
into locking groove 37. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.