Novel locking mechanism and reel for retractor

An automobile retractor comprising: (a) a base (6); (b) a winding reel mounted for rotation on said base (6), said winding reel comprising a cylindrical hollow tube (12) having a slot (36) extending substantially along the length thereof, said slot having a first edge (34) and a second edge (35); (c) a locking dog (23) having teeth (39) and being mounted on the external peripheral surface of tube (12) for rotation relative thereto; (d) a locking ring (21) on base (6) disposed in potential mating relationship with locking dog (23); (e) locking dog (23) having an opening (28) therein and a projection (29) into opening (28), opening (28) fitting over one end of tube (12) with the projection (29) fitting into mating relationship with slot (36); (f) at least a significant portion (37) of the inner surface of said opening having a configuration that conforms with the outer peripheral surface of tube (12); (g) actuating ratchet wheel (43) rotatably mounted concentrically with respect to tube (12) and being connected to said locking dog via pin (45) and slot (49) whereby movement of said tube relative to said wheel causes the locking dog to rotate relative to said connection point and into locking engagement with said locking ring.

FIELD OF THE INVENTION 
This invention relates to a novel locking mechanism for a retractor, more 
particularly an emergency locking retractor for seat belts. 
DESCRIPTION OF THE PRIOR ART 
Reel type seat belt retractors, which allow extension of the belt in 
response to a pull under normal operating conditions, but which sense a 
sudden pull on the belt or deceleration of the vehicle as may occur in an 
accident to lock the reel against further belt extension, provide a number 
of advantages over alternate forms of retractors. They allow the belt 
system to be used by occupants of different size without adjustment, and 
allow the occupant to move freely in his seat without releasing the belt 
or causing the belt to tighten on the occupant as automatic locking 
systems do. Several factors tend to complicate the retractors of this type 
and/or reduce their reliability. There is the antithetical design 
requirement that a relatively small force actuate the locking mechanism 
which must withstand the very high forces generated by the impact of the 
moving occupant's body in a sudden vehicle deceleration. Another design 
problem relates to the fact that the reel must be stopped while it is 
moving relatively rapidly and locking parts do not always meet in the same 
position. 
One known type of emergency locking retractor employs a rotatable flywheel 
supported on the reel urged by a spring to move with the reel in a web 
extending direction. If the reel accelerates relatively slowly, as it does 
in normal usage, the forces required to overcome the inertia of the 
flywheel will not be sufficient to compress the spring and the flywheel 
will rotate with the reel; however, when the reel is rapidly accelerated 
as by the occupant's body moving forward rapidly in the seat, the inertia 
forces cause the flywheel to slip relative to the reel, comressing the 
spring. A locking dog is supported on the reel and articulated to the 
flywheel so that the locking dog moves outward radially in response to 
relative motion between the two and engages an internal circular ratchet 
surface formed on a member which is fixed to the reel base side wall. This 
engagement locks the reel against further rotation. In retractors of this 
design, the dog must be relatively lightweight so the flywheel is well 
balanced, yet the dog must withstand the impact of its engagement with the 
stationary ratchet and absorb the forces which restrain the occupant's 
body against forward motion. Since the dog may move outwardly at any 
angular position of the reel, difficulty is encountered in designing the 
dog and ratchet to withstand the large impact forces. This type of 
retractor is exemplified in U.S. Pat. Nos. 3,416,747 and 3,955,774, and 
French Pat. No. 2,279,430, filed July 25, 1975. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a simple, strong and reliable 
reel shaft locking mechanism combination for retractors, which is 
economical and easy to fabricate and assemble. 
In summary, the invention comprises a device comprising: 
(a) a base; 
(b) a winding reel comprising a generally cylindrical hollow tube mounted 
for rotation on said base and having a slot extending substantially along 
the length thereof, said slot having a first edge and a second edge; 
(c) a locking dog having teeth and being mounted adjacent the external 
peripheral surface of said tube for rotation relative thereto; 
(d) a locking ring on said base disposed in potential mating relationship 
with said locking dog; 
(e) said locking dog having an opening therein and a projection into said 
opening, said opening fitting over one end of said tube with the 
projection fitting into mating relationship with said slot; 
(f) at least a significant portion of the inner surface of said opening 
having a configuration that conforms with the outer surface of said tube; 
(g) actuating means rotatably mounted with respect to said tube and being 
connected to said locking dog at a point radially spaced from the axis of 
the reel and remote from said projection whereby movement of said tube 
relative to said wheel causes the locking dog to rotate relative to said 
locking ring. 
A presently preferred embodiment comprises an emergency locking seat belt 
retractor comprising: 
(a) a base including upstanding side walls having plastic bearings mounted 
thereon to provide bearing surfaces; 
(b) a winding reel comprising a cylindrical hollow tube mounted for 
rotation on said bearings having a slot extending substantially along the 
length thereof, said slot having a first edge and a second edge; 
(c) a shaft extending through the center of said tube, and secured against 
rotation relative to said reel; 
(d) a spring and cover mounted on one of said side walls; said spring being 
articulated to said shaft to urge the shaft, reel and belt into the 
retracted rolled up condition; 
(e) a locking dog having a plurality of teeth on the external surface 
thereof and having an opening therein, said opening being defined by a 
generally arcuate surface, interrupted by: (i) a projection having concave 
sides and rounded edges at the top thereof and its juncture with said 
arcuate surfaces, and (ii) a bearing surface remote from said projection 
and of essentially the same radius as the peripheral surface of said tube; 
(f) a locking ring mounted on the second of said side walls and having 
teeth on the internal surface thereof for mating relationship with said 
teeth of said locking dog; 
(g) said locking dog being mounted adjacent the peripheral surface of one 
end of the tube with the projection fitting into mating relationship to 
said slot; 
(h) an actuating ratchet wheel rotatably mounted on said shaft for rotating 
movement relative to said locking dog; a pivotal connection between said 
locking dog and said actuating ratchet wheel; the pivotal connection on 
the locking dog being at a point radially external to the outer peripheral 
surface of the tube and remote from the projection, whereby rotating 
movement of the tube relative to said actuating ratchet wheel causes one 
edge of said slot to engage the projection and move said locking dog about 
said pivotal connection into locking relationship with the locking ring; 
and at the point of locking, the peripheral surface of the tube comes into 
mating relationship with said bearing surface to provide additional force 
against said locking dog to maintain it in locked relationship with said 
locking ring, 
said relative movement being caused by a retarded movement of said 
actuating means caused by the inertia thereof relative to reel tube 
accelerations and/or by an inertial sensor being actuated by deceleration 
of the vehicle to lock said actuating means against further rotational 
movement. 
The hollow tube is simple and easy to fabricate by stamping or rolling from 
flat sheet steel. The locking dog of the invention may be stamped out from 
flat sheet stock also and the whole retractor is easily assembled from one 
side in a stacking type of assembly that is susceptible of automated 
assembly.

DETAILED DESCRIPTION 
Referring to FIG. 1, the retractor 5 comprises a base 6, including 
upstanding side walls 7, 8. On the exterior of the side walls are mounted 
spacer bearings 9 and 11 designed to provide bearing surfaces for the 
winding reel tube 12. On retractor side wall 7, there is secured a spring 
and lever assembly 13 adjacent bearing 9. Arbor 14 is secured inside the 
end of tube 12 against rotation relative thereto and onto shaft 15. Arbor 
14 has a slot 17 adapted to receive the inner end 18 of spring 19, thereby 
always urging the reel tube 12 in the belt rewind direction. 
The side walls 7, 8 are secured in rigid spaced relationship by tie bar 20. 
A locking ring 21 having internal teeth 22 is secured to side wall 8 
adjacent bearing 11. The locking dog 23 is mounted adjacent the peripheral 
surface on tube reel 12. Locking dog 23 is actually supported by the 
interaction of the slot 36, projection 29, pin 45, slot 49 and spring 67. 
The locking dog 23 has an opening 28 therein and a projection 29 into said 
opening. The projection 29 has a configuration including concave side 
surfaces 30, 31 and rounded edges joining said side surfaces with a top 
surface 32 and the internal surfaces 33 of the opening 28. The side 
surfaces 30, 31 mate with edges 34, 35 of tube slot 36. A significant 
portion (e.g. 10.degree.-60.degree.) of the internal surface 33 comprises 
a bearing surface 37 having an arcuate configuration with a radius 
substantially equal to the radius of the outer peripheral surface 38 of 
tube reel 12. In addition, the locking dog 23 has teeth 39 designed to 
mate in locking relationship with teeth 22 when the locking dog 23 is in 
its activated locking position as shown in FIG. 4. Preferably, there is an 
equal number and configuration of teeth 22 and 39, and lock dog 23 may be 
cut from the same blank as ring 21 to conserve material. 
An inertial deceleration sensing device 40 with locking pawl 41 is also 
mounted on side wall 8. Presently preferred is the device disclosed in 
U.S. Pat. application Ser. No. 915,695, filed June 15, 1978. 
Retainer mechanism 42 is secured to end of tube 12 to retain locking dog 23 
in axial position on tube reel 12, and serves as a bearing surface for 
shaft 15. Actuating ratchet wheel 43 is freely rotatably mounted on end 
portion 44 of shaft 15. Wheel 43 is connected to locking dog 23 through 
outwardly projecting pin 45 mounted on locking dog 23 and mating in slot 
49 in wheel 43. 
Actuating ratchet wheel 43 has teeth 46 adapted to be engaged by pawl 41. 
Clutch spring 67 is fixed at one end at hole 50 and at its other end to 
pin 45 to continually urge pin 45 against end 47 of slot 49. This 
connection allows for absorption of any shock due to mismating of teeth 
22, 39. 
Web sensing spring 52 is fixed at one end to slot 53 in retainer 42 and at 
its other end to one of four holes 54. Depending on the hole into which 
the spring end is inserted, the responsiveness to locking upon reel 
acceleration can be varied. 
Screw 55 secured retainer 42 onto end 44 of shaft 15 and flanges 56 retain 
wheel 43 in axial position on shaft end 44. A housing member 57 via its 
snap in attachments 58 aids in securing the assembly in position. Cover 59 
is secured to wall 8 with rivets 60. 
Webbing spool 61 surrounds tube 12 to provide a spool for webbing 62. 
Washer 64 fits over end 65 of shaft 15 and inside tube 12 as an aid 
against deformation of tube 12. 
Belt 62 is secured to reel tube 12 by inserting the belt into slot 36 
around shaft 15 where it is trapped against withdrawal by wedge bar 63. 
To assemble the seat belt retractor of the present invention, the operative 
parts can be generally assembled by a stacking action, sliding one into 
position next to the other. This feature and the simplicity of the 
retractor itself provides a low cost but reliable, dual sensitive 
automatic locking retractor. 
In operation, the locking means is activated in either of two ways. If the 
reel tube 12 is accelerated by a sudden pull on the belt 62, the heavier 
inertial moment of actuating wheel 43 causes it to resist movement and 
thereby apply force "F.sub.1 " against the pin 45 (via end 47 of slot 49) 
as shown in FIG. 3, thereby causing the locking dog 23 to rotate relative 
to tube 12 by reason of the force "F.sub.2 " on the locking dog through 
edge 34 of reel tube 12. The motion of the locking dog 23 into engagement 
with the teeth 22 of locking ring 21 can be seen by reference to FIGS. 
2-4. 
The other way of locking the reel so as to prevent further extraction of 
the belt is initiated by sudden deceleration or acceleration of the 
vehicle to actuate sensor 40, thereby moving pawl 41 into engagement with 
ratchet teeth 46 which will lock the wheel 43 and pin 45 against further 
movement thereby causing the locking dog 23 to move into locking 
engagement with ring 21 upon the slightest withdrawal of belt 62 and 
consequent movement of reel 12. Either or both (preferably both) of these 
mechanisms can be built into the invention. 
The device of the invention provides a device which is economical, yet 
effective. The tubular slotted configuration of reel tube 12 allows it to 
be easily formed from sheet stock and at the same time provides a slot to 
allow easy assembly of the belt to the reel and provides a bearing surface 
and actuating mechanism for locking dog 23 adjacent the outer edge of the 
reel, so as to get improved leverage acting on locking dog 23 to improve 
the realiability of the locking mechanism. In addition, the forces acting 
to maintain the locking dog in locked position are spread over a 
substantial portion of the surface of the tube reel via bearing surface 37 
.