Protractive force responsive safety belt locking apparatus

A locking apparatus for use with safety belts of the type protracted and retracted on a spool which is locked by inertia forces in an emergency. The safety belt passes through a clamping assembly which is activated upon sliding movement of the retractor reel from protraction forces in the locked state greater than a pre-established threshold amount.

BACKGROUND OF THE INVENTION 
The present invention relates to safety belt systems employed in 
automobiles and the like for restraining passengers in their seats during 
emergency conditions and, more particularly, to safety belt restraint 
devices employed for restraining a single safety belt and employing a reel 
from which the safety belt is protracted and retracted. 
The use of safety belts for occupant restraint in vehicles has been known 
for many years. In an effort to secure the benefits of such systems, there 
has been a constant effort in the industry to improve the systems in order 
to make them better in operation while, at the same time, of minimal 
interference to the occupant so as to promote their increased use. 
Many such safety belt systems in present used employ a spring-wound reel at 
one end of the safety belt around which the safety belt is wound for 
protraction and retraction. Such systems offer relatively unconfined 
freedom of movement for the occupant during normal conditions. In an 
emergency condition, the reel is locked by an appropiate mechanism to 
prevent protraction of the belt and thereby restrain the occupant for the 
duration of the emergency. The primary locking of the reel is often 
accomplished by an inertia responsive device such that the occupant is 
restrained during periods of excessive acceleration and deceleration, as 
well as upon a striking force against the vehicle from the side. 
In studying such systems, it has been found that upon the locking of the 
reel itself, a certain amount of protraction of the safety belt can still 
occur depending on the manner in which the belt is wound about the reel 
and its relative compactness. That is, the belt may slide along itself, 
compacting the layers on the reel, for a given amount of time. In 
co-pending application Ser. No. 227,275 filed Jan. 28, 1981, by 
co-inventor Avraham Ziv herein and entitled SAFETY BELT WEBBING EMERGENCY 
LOCKING APATUS, an improvement to such devices was shown for preventing 
such continued protraction following lockup of the reel. In the apparatus 
of that invention, a clamping wedge is disposed in front of the reel, 
having the seat belt pass therethrough. A second inertia responsive device 
is connected to activate the clamping wedge so as to directly clamp the 
belt upon a second level of inertia being encountered greater than that 
necessary to primarily lockup the reel. 
Heavier individuals tend to compact the layers of seat belt upon the reel 
and achieve protraction after lockup to a greater degree than lighter 
individuals. This weight or force responsive protraction is independent of 
the degree of inertia involved. Wherefore, it is the object of the present 
invention to provide an alternate embodiment to the invention of the 
aforementioned application which alternate embodiment is responsive 
protraction forces on the seat belt webbing itself following primary 
lockup rather than inertia forces on the vehicle. 
SUMMARY 
The foregoing objectives have been met in an inertia responsive locking 
seat belt retractor for a vehicle having a frame mounted to the vehicle, a 
toothed retractor reel having a safety belt webbing wound thereon for 
protraction and retraction mounted to the frame and an inertia-activated 
pawl mounted to the frame for engaging the reel to prevent protraction of 
the safety belt in an emergency by the improvement comprising clamping 
means carried by the frame and having the safety belt passing operably 
therethrough for selectively clamping the safety belt against further 
movement relative to the clamping means; and, means operably connected to 
said clamping means for operating said clamping means to clamp the safety 
belt against further relative movement in response to a protraction force 
on the safety belt which exceeds a predetermined threshhold amount. 
More specifically, a wedge-shaped clamp member is mounted in front of the 
retractor reel and has the seat belt passing therethrough. The retractor 
reel is slide-mounted and spring-biased to a deactivated position. Upon 
lockup due to the primary inertia-responsive mechanism, the protraction 
force on the seat belt tends to pull the reel assembly towards the 
wedge-shaped clamp member against the force of the bias spring. Upon the 
protracting force exceeding the bias force of the spring, the retractor 
moves forward to cause the wedge-shaped clamp member to clamp and hold the 
seat belt. In one embodiment, a separate spring-loaded locking mechanism 
is tripped by the movement of the retractor reel requiring it to be reset.

DESCRIPTION OF THE PRESENT INVENTION IN TWO EMBODIMENTS 
Referring first to FIGS. 1-3, a seat belt retractor 10 is shown 
incorporating the present invention in a first embodiment. Retractor 10 
comprises a frame 12 adapted to be mounted vertically to the vehicle as at 
a door post or the like. An inertia-activated retractor reel assembly, 
generally indicated as 14, is slidably mounted to the frame 12. Reel 
assembly 14 is, itself, of a generally known variety wherein a toothed 
reel 16 is journal-mounted on shaft 18 between the parallel side members 
20 of a generally U-shaped mounted member 22. A spring (not shown) is 
contained within housing 24 to spring-bias the reel 16 towards the 
protracted position. The seat belt webbing 26 is attached to and wound 
about the toothed reel 16 such that as the seat belt webbing 26 is 
protracted, the spring within spring housing 24 is wound tighter to 
retract the seat belt webbing 26 onto toothed reel 16 by revolving it in 
the opposite direction as the protracting force thereon is released. A 
pawl member 28 is disposed against the teeth 30 on reel 16 to be forced 
into engagement therewith to, thereby, lock the toothed reel 16 against 
further protraction by pendulum 32 during a state of inertial force above 
a preselected amount. According to the present invention, however, rather 
than the mounting member 22 being firmly and fixedly attached to the frame 
12, mounting member 22 is mounted by attaching rivets 34 through elongated 
slots 36 in the backplate 38 of mounting member 22. The elongated slots 
have sufficient clearance around rivets 34 to allow the mounting member 22 
and, thereby, the entire inertia-activated retractor reel assembly 14, to 
slide vertically up and down over a distance of about 3/8 of an inch. A 
spring 40 is attached between a first post 42 on the frame 12 and a second 
post 44 on the backplate 38 to, thereby, bias the retractor reel assembly 
14 in the down or disengaged position with respect to the clamp assembly 
to be described hereinafter. 
A clamp block assembly 46 is disposed above the inertial-activated 
retractor reel assembly 14. Clamp block assembly 46 comprises a backblock 
48 attached to the frame 12 and having a front bearing surface 50 of a 
non-chafing material at the level of the seat belt webbing 26 and parallel 
thereto over which the seat belt webbing 26 passes during protraction and 
retraction thereof. A pair of parallel spaced side members 52 are attached 
to the backblock 48 on either side of the seat belt webbing 26 extending 
thereabove. A fixed wedging block is connected to the two side members 
spaced from the seat belt webbing 26. Fixed wedging block 54 has a wedging 
surface 56 sloping towards the seat belt webbing 26 is the upward 
direction. A movable wedge 58 is disposed between the wedging surface 56, 
the side members 52, and the top of the seat belt webbing 26. Movable 
wedge 58 has a first outer surface 60 parallel to the seat belt webbing 26 
and a second outer surface 62 parallel to the wedging surface 56 of fixed 
wedging block 54. So constructed, it will be understood that as the 
movable wedge 58 is moved upward, the spacing between the first outer 
surface 60 and the seat belt webbing 26 will be increasingly diminished 
until the seat belt webbing 26 is firmly gripped between the front surface 
50 of backblock 48 and the first outer surface 60 of movable wedge 58. 
Surfaces 50 and 60 are preferably of a high-strength, resilient material 
having a high coefficient of friction. 
An activator bar 64 is disposed below the movable wedge 58. Activator bar 
64 is rotatably mounted to frame 12 at pivot point 66. A projection 68 is 
disposed to contact the lower surface of movable wedge 58. At the side 
opposite pivot point 66, an L-shaped mounted member 70 is attached to side 
member 52. The end of actuator bar 64 passes through a slot 72 in the 
mounting member 70. A spring 74 is connected between a first post 76 on 
mounting member 70 and a second post 78 on the end of actuator bar 64 
opposite the pivot point 66. Spring 74 thus tends to bias the actuator bar 
64 and pivot point 66, in particular, against the movable wedge 58, 
tending to force it into clamping juxtaposition with the seat belt webbing 
26. Bell crank 80 is disposed to pivot around pivot point 82 adjacent the 
end of actuator bar 64 and to be movable to a position as shown in FIG. 2 
wherein actuator bar 64 is held in a cocked position against the bias of 
spring 74 with the movable wedge 58 in a clearance position with respect 
to the seat belt webbing 26 as shown in FIG. 3. 
The details of clamp block assembly 46 shown heretofore are substantially 
identical to that portion of the invention shown in the above-mentioned 
co-pending application of Avraham Ziv, The co-inventor herein. That 
portion of the apparatus per se, therefore, forms no part of the present 
invention in and of itself. The point of novelty of the present invention 
resides in the apparatus to be described hereinafter which causes the 
activating force of the clamp block assembly 46 to be entirely different. 
Whereas in the above-mentioned co-pending patent application, the bell 
crank 80 was moved by inertial forces, in the present application, the 
bell crank is moved as a result of the protractional forces on the seat 
belt webbing 26 and, in particular, as a result of the movement of the 
inertia-actuated retractor reel assembly 14 in the manner previously 
described as a result of tension in the seat belt webbing 26 following 
lockup of the reel 16. 
To effect this operation, an actuator arm 84 is connected to the mounting 
member 22 of reel assembly 14 on one end and extends to contact the end of 
the bell crank 80 which is not in locked engagement with the actuator bar 
64. The actual operaton of the apparatus under emergency conditions can 
been seen with reference to FIGS. 4 and 5. In an emergency situation, 
inertial force on the pendulum 32 rotates the pawl member 28 into 
engagement with the teeth 30 of the toothed reel 16 preventing further 
rotation thereof. Upon the application of a further protracting force on 
the seat belt webbing 26 as indicated by the arrow 86, the mounting member 
22 is pulled upward against the force of spring 40 by virtue of the 
slidable mounting of the attaching rivets 34 in the elongated slots 36. As 
the mounting member 22 moves upward, so also does the actuator arm 84 as 
indicated by the arrow 88. In so doing, the bell crank 80 is rotated 
clockwise as indicated by the arrow 90. In rotating, the opposite end of 
the bell crank 80 comes out of engagement with the end of actuator bar 64 
allowing spring 74 to move actuator bar 64 upward, pivoting clockwise 
about the pivot point 66, and thereby allowing the projection 68 to push 
the movable wedge 58 into clamped arrangement with respect to the seat 
belt webbing 26 as shown in FIG. 5. 
As will be understood, in the foregoing embodiment, once the bell crank 80 
has been released from its engagement with the end of actuator arm 64, 
spring 74 forces the movable wedge 58 into its clamped position with 
respect to the seat belt webbing 26. Accordingly, the mechanism must be 
reset before the seat belt webbing 26 can be moved in either direction.