Energy absorbing restraint seat back recliner for application on a restraint safety seat

A restraint seat back recliner construction with a high strength double-wall recliner body that packages a lead screw mechanism inside the body to create a shoulder belt load carrying, single-sided, recliner system. A unique slot in the lower body is employed that guides the movement of a traveling nut pinion at the end of a lead screw and connects the upper and lower body, thereby providing reclining action and acting as a secondary safety stop mechanism. A unique end detail of a guide slot and a lead screw end pinion design permits controlled occupant deceleration during a frontal vehicle crash. Application of two-door, four-door, power, manual, single and double sided recliners are shown.

BACKGROUND OF THE INVENTION 
Many or most current seat recliners "work" on the principle of mesh gear 
teeth mounted on a rotating shaft. Partial (sector) gear and planetary 
gear systems are commonly utilized. Another common current seat recliner 
mechanism is a sliding cylinder mechanism within a locking spring "Porter" 
device. Both provide a mechanism to recline a seat back relative to the 
lower seat frame. 
An object of the present invention is to provide an improved recliner 
mechanism for a vehicle seat that is strong, compact, and relatively 
inexpensive. Another object of the present invention is to provide a 
recliner that is continually adjustable and has improved safety 
characteristics under crash conditions, especially when the invention is 
used for "restraint seating", which is seating wherein the upper end of a 
shoulder safety belt is mounted to the seat back itself, such that the 
seat back restrains crash stresses. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an improved structural restraint 
seat back recliner consisting of a drive mechanism packaged inside a high 
strength recliner body. The recliner body reacts occupant belt loads that 
are attached to the seat frame and has unique features to mount and 
control the internal mechanism travel. 
The drive mechanism is a lead screw (also called a power screw or worm 
screw) mechanism or a ball screw. A ball screw is similar to a lead screw 
but has less friction. The screw mechanism is utilized with one moving and 
one stationary pinion. The screw can be driven manually or powered by an 
electric motor and appropriate gear set. 
The recliner body includes two plates spaced apart on either side of the 
drive mechanism to provide good structural support to the mechanism that 
reacts or resists high restraint loads. The body upper is further 
closed-off to form a partial box section to create improved torsional 
stiffness. The body attachment members for connecting the body plates 
together are sleeved and positioned side by side over the plates to 
improve structural performance. 
This design application allows the use of a single sided restraint 
recliner. The term single sided means the seat back has a freely pivoting 
hinge on one side of the seat back and a locked recliner mechanism on the 
other side. A dual recliner system has a passive lock mechanism on both 
sides. The single sided recliner has advantages of lower cost, and dual 
sided recliners have the advantage of improved stiffness on the inboard 
side of the upper seat back. 
The present invention includes an improved slot design in the lower body 
that limits the range of recliner travel during normal seat operation. 
However, the slot acts as a design safety feature for a restraint seat 
under crash conditions, wherein the end of the slot deforms under severe 
loads to increase forward seat travel limits while dissipating stress. The 
end detail of the recliner slot is designed to provide controlled recliner 
deformation which results in controlled occupant deceleration and occupant 
energy absorption. There are many variations possible for an energy 
absorbing recliner with a threshold break away sliding shaft and designed 
mechanical resistance to movement. 
The present invention is a good design solution for four-door recliners in 
that the recliner system is always engaged and has infinite adjustment by 
virtue of use of a lead screw. The restraint guide slot recliner body adds 
a secondary safety feature for restricting recliner forward movement in 
the event that the internal mechanism fails. The design safety stop slot 
can be utilized on both sides of the seat, either with double or single 
sided recliners and can also be utilized in conjunction with a pivot on 
the inboard side to restrict four-door recliner forward rotation. 
The present invention adds a split upper body with a hook latch to permit a 
two-door forward dumping recliner. Since a forward dumping recliner could 
be potentially disengaged during a frontal vehicle crash, a secondary 
inertia latch device is designed to improve occupant safety for a 
restraint seat. 
The present invention has application to two-door and four-door recliners, 
power and manual recliners, and singled and double sided recliners. 
The use of a tightly packaged recliner mechanism employing a linear drive 
such as a power screw or ball screw packaged inside a high strength upper 
and lower body of the recliner provides an extremely strong mechanism to 
adjust the seat back angle at a reasonable low weight, cost and relatively 
small vehicle package. The design meets the needs of infinite seat back 
angle adjustment, with continuous seat latch engagement. 
The present invention shows two basic types of recliners: a power recliner 
and a manual recliner. Both are four door vehicle recliners where there is 
no need for a "quick dump" (forward pivoting) feature to provide access to 
the rear seat for ingress and egress. The four door recliner version has 
the advantage of positive engagement at all modes of operation. This is an 
extremely safe and desirable feature for a safety restraint seat that 
mounts the upper shoulder belt on the seat back frame. The seat recliner 
screw mechanism is designed to withstand the loading of a 35 mph vehicle 
collision by itself, and it has a secondary fail-safe feature of limited 
travel, as the upper and lower body slide relative to one another within a 
guide slot. The recliner is locked from further rotation by virtue of the 
slot limiting feature and will prevent seat rotation if the lead screw 
fractures at loading greater than created during a 35 mph vehicle 
collision. 
In another aspect of the present inventione a two door recliner is produced 
by modifying the upper recliner body to dump (pivot) forward. 
Other features of the recliner mechanism of the present invention are: 
Inertia Lock Feature 
One method to prevent seat rotation during an automotive collision is with 
the use of an inertia lock located at the recliner pivot. An inertia 
mechanism locks-up at a predetermined g level and engages a gear with a 
stop plate, attached to the upper and lower recliner body respectively. 
This feature provides a secondary latch feature for a two-way forward dump 
latch in the event the pivoting latch is not engaged during a vehicle 
forward crash. The advantage of the inertia lock is that it permits 
down-sizing of the lead screw and/or utilizing a more conventional light 
weight recliner mechanism to provide normal seat recliner usage whereby 
depending on the inertia lock during a crash situation, along with the 
seat recliner body limiting slotted travel feature. 
Power Recliner Feature 
The power recliner has the advantage of smooth, easy recliner operation by 
virtue of an electric motor rotation of the lead screw powered in either 
forward or reverse. Advancement of the lead screw moves the pinion 
relative to the lead screw to provide movement of the recliner upper body 
and pivot about the recliner pivot point. 
Manual Recliner Feature 
For the manual recliner, a hand-wheel "knob" is turned manually to provide 
the same movement with some effort, but at a low cost versus the power 
recliner. The manual option may utilize a double lead thread (change of 
screw pitch) to reduce the number of revolutions of the knob to recline 
the seat back. In addition to a screw, a linear sliding mechanism can be 
utilized that operates by lever instead of a hand wheel knob. The 
mechanism can be down-sized, and downgaged for application of a 
non-restraint seat where there are lower structural requirements. Design 
analysis indicates the present invention power or manual screw recliner, 
with a magnesium housing, is approximately three times stronger at nearly 
the same weight of a current steel recliner.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A recliner side view and projected end view are shown in FIGS. 1A-1C. The 
upper recliner body 1 is attached to the upper seat back 14 at fastener 
openings 15 and to the lower recliner body 2 by a pivot shaft 32 at the 
common pivot hole 3. A lead screw 4 is attached to the upper body through 
the drive nut travelling pinion 5, which has a pin 30 extending from the 
sides thereof. The other end of the lead screw is mounted to the 
stationary pinion 6. The stationary pinion 6 is pivot mounted to the lower 
body and the pin on moving pinion 5 travels in a guide slot 7 in the lower 
body. The moving pinion 5 is also pivot mounted to the upper body. 
Rotation of the lead screw by drive cable 9 and remote motor 10 causes the 
pinion nut 5 to travel axially along the lead screw length and along the 
path of the slot to move the upper body relative to the lower body, 
creating rotation (reclining) of the seat back 14 around pivot shaft 32. 
Also shown in FIGS. 1 and 2 is the option of a manual recliner where the 
same or similar lead screw mechanism is driven by a hand wheel 12 that 
turns a bevel gear 11 mounted so as to rotate the lead screw. The upper 
body comprises a hollow, closed section beam that increases in 
cross-sectional area as the body extends downwardly to a position 
approaching the lower end of the body, where the bending moment is 
greatest. 
The lower body 2 is attached to the seat track 13 by sleeved attachment 
holes 16 to improve structure. The seat track is mounted to the vehicle 
structure by a floor-mounted pedestal or the like. 
During a frontal vehicle crash, the seat back upper shoulder belt bending 
moment load 18 is reacted at 19 through the upper body and moving pinion. 
The screw thread prevents axial movement of nut pinion 5 and transfers the 
load to the stationary pinion 6 and through the lower recliner body 
directly to the seat tracks. 
The end view of the recliner in FIG. 1B shows the relative in-line center 
axis of the recliner, seat track, and back structure to provide an 
efficient structural system with minimum eccentric loading and minimum 
mass. 
A partial perspective view of the restraint load carrying recliner is shown 
in FIG. 2. The mechanism is packaged in between spaced plates defining the 
upper 1 and lower body 2 housings. The upper and lower body both have a 
pivot hole 3 through which the pivot shaft 32 extends to connect the two 
bodies and create a pivot location for the recliner. The lower body has a 
slot 7 for the traveling pinion guide and the upper body has a round hole 
10 for the pin mounted to the traveling pinion 5, such that movement of 
the traveling pinion nut 5 creates rotation (reclining) of the upper body 
relative to the lower body. 
The traveling pinion nut is moved linearly or axially by rotation of the 
lead screw 4 that is threaded for part of its length. The smooth shaft 
portion of the lead screw rotates in the stationary pinion 6 that is 
connected by pin 38 to a hole in the lower body. 
A drive shaft connection 8 with appropriate keyed end is employed to 
connect a drive cable and the cable is turned either by a remote motor or 
a manual handle wheel 12. 
Arrow 17 (FIG. 2) represents near linear movement of the travel pinion nut 
along the lead screw and arrows 23 and 24 represents rotational movement 
of the screw and upper body respectively. The design end slot has unique 
lance opening tapper slot 25 designed to deform at crash threshold levels 
and provide additional controlled travel and energy absorption of the 
occupant by virtue of a restraint seat loading the recliner end slot. 
A two door vehicle recliner 40 is shown in FIGS. 3A-3C, which represent a 
scaled side view, an end view, and a partial side view of the mechanism 
after crash load displacement. 
Similar to FIG. 1, the upper body 41 is connected to the die cast magnesium 
lower body 42 at the recliner pivot 43. A lead screw 44 has a moving 
pinion traveling nut 45 at intermediate double plates 57, also pivotally 
mounted on pivot 43, are positioned between upper body 41 and lower body 
42. Intermediate double plates 57 are attached to each side of the 
travelling pinion nut of the screw drive mechanism in the same manner as 
the travelling pinion nut is attached to the upper body of FIG. 1. A metal 
double hook 54 is employed to selectively block pivotal movement of upper 
body 41 with respect to intermediate plates 57. One end and a stationary 
pinion 46 at the other end. The moving pinion rides in a guide slot 47 in 
the lower body and the end of the guide slot48 has a unique stop tap and 
tapping end to resist pinion movement at a controlled collapse rate. 
While die cast magnesium is a preferred construction of the lower body in 
all embodiments, the lower body as well as the upper body also could be 
formed of other high strength material such as martensitic steel, high 
strength steel, or aluminum. A composite plastic also could be employed. 
The lead screw mechanism is case hardened. 
A press-on bushing 49 is located next to the lead screw shaft to resist 
pinion shaft movement. However, the bushing 49 is designed to break loose 
from the shaft and slide at a threshold crash load such as 10,000 pounds 
axially. The lead screw shaft, which is smooth at this end, will slide 
through the stationary pinion, resisted by slot end 48, and crushable 
sleeve member 50 thereby permitting forward displacment of the recliner, 
seat back, and occupant shoulder belt at a controlled rate to absorb 
occupant impact energy. FIG. 3C shows the displaced lead screw 44, pinion 
45, crushed sleeve 50 and displacement 58 of the shaft assembly end points 
under a vehicle crash load. 
A nut 51 is at the end of the lead screw shaft to limit shaft travel, and a 
key 52 is at the shaft end center used to drive and rotate the lead screw 
to create normal recliner movement. 
A metal double hook 54 is utilized to latch to the intermediate double 
plate 57. They are connected with a circular return spring 61 mounted 
around pivot axis 63. Occupant release of hook 54 allows dumping of the 
recliner upper body forward. An inertia latch consisting of a pivoting 
metal bar 59 having a weighted lower end pinned to the lower body and a 
set of metal teeth 68 spaced around the pivot axis of the upper body. In 
the event of a forward designated g-level, such as three g's (deceleration 
three times the force of gravity), the weighted lower end of bar 59 will 
swing forward as shown by arrow 60 to engage teeth 68 and lock-up and or 
resist forward recliner rotation. Therefore the inertia latch serves as a 
secondary recliner safety lock. Bar 59 will swing back to unlock position 
at normal one g gravity. Item 53 is the seat track, shown for reference. 
FIGS. 4A and 4B show a side view and end view of a four door metal 
fabricated recliner 70 with an internal lead screw 74 and traveling nut 
pinion 75 pinned to the upper body 71 and riding in a slot 77 in the lower 
body 72. 
A right angle gear set is contained in housing 81 and pin-mounted to the 
lower body at 76. An extension drive shaft 80 exits the lower body through 
a round hole with a unique end slot treatment 79, which is similar to the 
energy absorbing end slot 78 at the traveling nut pinion. When a forward 
occupant upper shoulder belt load is applied, as shown by arrow 84 on the 
recliner body, it is reacted by the traveling nut pinion 75, as shown by 
arrow 85. The nut transfers the load to pivot mounting end of the lead 
screw mechanism at 76 and is resisted as shown by arrow 87. 
At a prescribed threshold force level, pinion mount 76 can elongate and/or 
fracture causing the lead screw to displace in the direction of arrow 85. 
This displacement is resisted by narrowing end slots 78 and 79 against the 
pinion and right angle drive shaft respectively. The continued 
displacement along the slot at a designated resistance force generate 
energy absorption and promotes occupant torso safe deceleration. 
Similar to other figures, a drive key shaft 82 is at the end of extension 
drive shaft 80. The upper recliner body is mounted to the seat back at 
fastener openings 95, and lower recliner body is mounted to the seat track 
fastener openings at 96. Stand-off rivets 93 are utilized in the 
construction of the double wall recliner bodies to join the wall and help 
create an improved structure. 
A displaced partial side view of an alternative mechanism is shown in FIG. 
4C, with the same mechanism components having the same numbers as in FIG. 
4a, i.e., energy absorber end slots 78, a front pivot mount 76 for the 
mechanism assembly, and guide slot 77. New is a split lead screw 104 
having an energy absorbing elongation sleeve 90 shown crimped over the 
split ends of the lead screw, such that at threshold axial force levels, 
the sleeve will elongate by virtue of its hump-back design, thereby 
causing controlled, limited displacement with additional resistance. 
Further resistance is created at gear housing mounting end slot 108.