GB2240706A

GB2240706A - Emergency locking seat belt reel with clamp

Info

Publication number: GB2240706A
Application number: GB9102040A
Authority: GB
Inventors: Yoshiichi Fujimura
Original assignee: Takata Corp
Current assignee: Takata Corp
Priority date: 1990-02-05
Filing date: 1991-01-30
Publication date: 1991-08-14
Anticipated expiration: 2011-01-30
Also published as: GB9102040D0; JPH03231055A; GB2240706B

Abstract

An emergency locking seat belt retractor reel is of the type in which the reel has an attached ratchet wheels 38, 94 which lock the reel in an emergency by means of pawl. Also provided is a belt clamp (Fig. 5 not shown) having a fixed part (124) and a pivoted pant (138). The pawl and ratchet mechanism is linked to this clamp so that in an emergency the belt is also clamped. The linking is via a rocker arm 146 having an engagement portion 148, the latter being engaged with a pin 140 on the pivoting part of the clamp. The device is characterised in that the pin 140 and/or the engagement part 148 of the rocker arm have the shape of a gear tooth or the inter-tooth space of gear teeth, see Fig. 2. <IMAGE>

Description

SEATBELT RETRACTOR Field of the Invention The present invention relates to retractors for use in a vehicular seatbelt system and in particular, to a seatbelt retractor designed to inhibit extraction of a seatbelt when vehicle collision or other accidents occur.

Related Art A conventional automotive vehicle includes a seatbelt system mounted to a passenger seat so as to protect a vehicle occupant during collision or other accidents. The seatbelt system typically includes a retractor mounted to a rigid member and designed to take up a seatbelt and operable to lock the seatbelt under an emergent circumstance.

The seatbelt is freely pulled out from the retractor so as to extend across the vehicle occupant. The seatbelt can also be extracted under a normal circumstance so as not to restrain the vehicle occupant. Once collision or other accidents occur, the resulting impact or sudden acceleration is sensed. A lock mechainsm is then active to lock a reel around which the seatbelt is wound. This allows the seatbelt to restrain the vehicle occupant so as to prevent him from being suddenly moved from the seat for protection purposes.

The reel lock mechanism is operable to positively lock the reel per se. However, the seatbelt may sometimes be extracted from the reel when the seatbelt is tightly wound around the reel even if the reel per se is locked. In order to prevent such extraction of the seatbelt when the seatbelt is tightly wound around, there has been proposed a seatbelt retractor as shown in Figs. 3 to 6.

As shown in Figs. 3 and 4, a frame 10 has a pair of parallel side walls 12 and 14 and a rear wall 16 extending between the side walls 12 and 14. A reel 20 occupies the lower half of the frame 10 to take up a seatbelt 18. A reel lock mechanism 22 also occupies the lower half of the frame 10 to lock the reel 20 in the event of an accident. A seatbelt lock mechanism 24 occupies the upper half of the frame 10 to inhibit extraction of the seatbelt 18 in the event of an accident.

The construction of the reel lock mechanism 22 will first be described with reference mainly to Fig. 4.

The side walls 12 and 14 have openings 26 and 28. A reel shaft 30 extends through the openings 26 and 28 and are rotatably supported through a bushing 32. The reel 20 has an opening into which the reel shaft 30 extends.

A return spring 34 has a central or inner end connected to one end of the shaft 30 and an outer end fixed to the side wall 12 through a cover 36. When the seatbelt 18 is extracted, the reel 20 is rotated in a direction to accumulate spring force in the return spring 34. When the seatbelt 18 is released, then the reel 20 is rotated under the action of the return spring 34 to automatically take up the seatbelt 18.

The reel 20 and the reel shaft 30 are rotated together in the direction of the arrow A, when the seatbelt 18 is extracted.

The reel lock mechanism 22 is attached to the outer side wall 14.

The reel lock mechanism 22 includes a ratchet wheel 38 unitarily connected to the outer end of the reel shaft 30.

A projection 40 extends outwardly from the ratchet wheel 38 in coaxial relation to the shaft 30. A tie plate 42 has an opening 43 through which the projection 40 extends. A lock ring 44 has a central opening 48 through which the projection 40 also extends. 50 denotes an arcuate spring element. The tie plate 42 has a substantially central opening 52 (spring hanger) with which one end of the spring element 50 is engaged.

The other end of the spring element 50 is engaged with an opening 54 (spring hanger) of the lock ring 44. The lock ring 44 has inner teeth 56. The spring element extends between the spring hanger 54 of the lock ring 44 and the spring hanger 52 of the tie plate 42 and is active to urge the lock ring 44 to rotate in the direction of the arrow A2.

A brake lever 58 has a base end pivotally mounted to the side wall 14 of the frame 10 by a pivot pin 60. This lever 58 has a free end engageable with the ratchet wheel 38. A pin 62 extends from the lever 58. The tie plate 42 has an opening 64 at its front end, and the pivot pin 60 also extends through the opening 64.

The lock ring 44 has two diametrically opposite integral extensions 66 and 68. The extension 66 is used to rotate the lever 68. The extension 68 is used to operate the seatbelt lock mechanism 24. The extension of the lock ring 44 has an arcuate elongate hole 70 into which the pin 62 is inserted.

A hook retainer 72 is secured to the projection 40 of the shaft 30 which in turn, extends outwardly through the central opening 48 of the lock ring 44. The hook retainer 72 has two diametrically opposite projections 76 and 78 at its peripheral edge to support a hook 74. The hook 74 has two openings 80 and 82 into which the projections 76 and 78 are inserted. By this arrangement, the hook 74 can reciprocates relative to the hook retainer 72 along a line extending between the two projections 76 and 78 (in the direction of the arrows B1 and B2).

A compression coil spring 84 is disposed between the hook retainer 72 and the hook 74 so as to urge the hook 74 in the direction of the arrow B1. The lock ring 44 has a pawl 86 on its outer peripheral edge which is engageable with the inner teeth 56 of the lock ring 44. A connecting pin 88 also extends from the outer side of the hook 74.

The hook 74 is normally urged in the direction of the arrow B1 under the action of the compression spring 84, or shifted to the left in Fig. 4. Under the circumstances, the pawl 86 is separated from the inner teeth 56.

A frictional engagement member 90 has an opening 92 adjacent to its outer peripheral edge. The connecting pin 88 extends through the opening 92. A flywheel 96 has a ratchet 94.

The frictional engagement member 90 is fit in the flywheel 96.

The flywheel 96 has a central opening in which the projection 40 of the shaft 30 is loosely fit. The flywheel 96 is a very short cylinder, and the frictional engagement member 90 is located within the flywheel 96. An arcuate spring 98 is placed on the outer periphery of the frictional engagement member 90.

The arcuate spring 98 is pressed against the inner periphery of the flywheel 96 so that the flywheel can be slidably rotated relative to the frictional engagement member 90 while a frictional force is being applied to the flywheel 96. 99 denotes a rivet inserted into a hole 40A of the projection 40 to hold the flywheel 96 in place.

With reference to Fig. 3, an operating unit 100 is mounted to the side wall 14 of the frame 10. The operating unit 100 generally includes a casing 104 fixed to the side wall 14, a barrel-shaped operating element 106 loosely held within the casing 104, an operating lever 110 having a projection 108 in contact with the upper surface of the operating element 106 and a support 112 designed to pivotably support the base end of the operating lever 110.

A cover 114 surrounds the reel lock mechanism 22 assembled as shown in Figs. 3 and 4.

With the seatbelt retractor thus constructed, the reel 20 and the shaft 30 are freely rotated to extract the seatbelt 18 when the operating lever 110 is disengaged from the flywheel 96. When the vehicle occupant releases the seatbelt 18, then the shaft 30 is rotated in a direction to take up the seatbelt 18 under the action of the return spring 34 which is located within the cover 36.

When a vehicle speed is substantially changed due, for example, to collision, the operating unit 100 is active to inhibit extraction of the seatbelt 18. In other words, if substantial acceleration is applied to the operating unit 100, operating element 106 is inclined to push up the operating lever 110 by the projection 108. This causes the front end of the operating lever 110 to engage with the ratchet 94 of the flywheel 96 so as to stop the flywheel 96.

The stoppage of the flywheel 96 results in corresponding stoppage of the frictional engagement member 90. When the vehicle collision occurs, the seatbelt 18 tends to be extracted to cause the reel shaft 30, together with the hook retainer 72 and the hook 74, to rotate in the direction of the arrow A1 (Fig. 1).

While the pin 88 is engaged with the frictional engagement member 90, the hook can not be rotated, but the hook retainer 72 is freely rotated in the direction of the arrow A1 so as to slide the hook 74 in the direction of the arrow B2. The pawl 86 then comes into engagement with one of the inner teeth 56 of the lock ring 44.

Under the circumstances, the lock ring 44 is rotated in the direction of the arrow Al. At this time, the extension 66 is rotated in the direction of the arrow A, to cause the lever 58 to rotate in the direction of the arrow C, since the pin 62 is in engagement with the elongate hole 70. This results in engagement of the front end of the lever 58 with the ratchet wheel 38 of the reel shaft 30. The reel shaft 30 and the frictional engagement member 90 are then positively locked.

The seatbelt lock mechanism 24 will next be described with reference to Figs. 3, 5 and 6.

A first grip 120 is attached to the upper half of the rear wall 16 of the frame 10. The first grip 120 includes a holder 123 vertically movable along the rear wall 16, a receiver 124 held by the holder 123, and a spring 126 disposed to urge the receiver 124 downwards. The receiver 124 has a corrugated front surface.

122 denotes a guide member for guiding the seatbelt 18.

As shown in Fig. 6, the guide member 122 is a frame and has upper and lower guide openings or slits 127 and 129 through which the seatbelt 18 passes. The guide member 122 is made of synthetic resin.

The side walls 12 and 14 of the frame 10 have openings 130 and 132, with a common central axis, through which a shaft 134 extends. A second grip 136 has support holes 139 in which the shaft 134 is fit to rotatably mount the second grip 136 to the frame 10.

As shown in Fig. 5, the second grip 136 is provided at its free end with a semicylindrical pusher 138. The pusher 138 has a corrugated surface which faces the receiver 124. The seatbelt 18 passes between the pusher 138 and the receiver 124.

A pin 140 (Fig. 3) has a circular section and extends from one side of the second grip 136. The pin 140 extends into an elengate hole 142 of the side wall 14 of the frame 10.

A rocker arm 146 is pivotably mounted to the side wall 14 of the frame 10 by a pivot pin 144. The rocker arm 146 is bent to provide a L-shaped configuration and has a recess 148 at its one end to engage with the pin 140. The rocker arm has a joint portion 152 at the other end which is pivotably coupled to a lever 150. The lever 150 is slightly augularly movable in the direction of the arrow E.

The lever 150 has a lower portion overlapped with the extension 68 of the lock ring 44. The lever 150 has a lower end 150a engageable with the ratchet wheel 38. A pin 154 extends from the lower portion of the lever 150 and is inserted into the elongate hole 156 of the extension 68.

A spring 158 extends around the pivot pin 144 and has one end engaged with an opening 160 which is formed in the side wall 14 of the frame 10, and the other end engaged with an opening 162 which is formed in the rocker arm 146. The spring 158 is disposed to urge the rocker arm 146 in the direction of the arrow G,.

Operation of the seatbelt lock mechanism 24 thus constructed will be described below.

Under a normal circumstance, the rocker arm 148 is urged in the direction of the arrow G1 under the action of the spring 158 so as to push the pin 140 in the same direction.

The pusher 138 of the second grip 136 is thus separated from the receiver 124 so as to allow the seatbelt 18 to freely pass between the pusher 138 and the receiver 124.

When a vehicle collision or other emergent accident occurs, the operating element 106 of the operating unit 100 is inclined to cause the operating lever 110 to engage with the ratchet 94 of the flywheel 96 as explained earlier. This results in rotation of the lock ring 44 in the direction of the arrow Al.

The seatbelt 18 is locked as follows: (1) The extension 68 of the lock ring is then rotated in the direction of the arrow A, to cause the pin 154 to move toward the lower end of the elongate hole 156.

Accordingly, the lever 150 is rotated in the direction of the arrow E; (2) The front end 150a of the lever 150 then comes into engagement with the ratchet wheel 38; (3) The ratchet wheel 38 is correspondingly rotated to push up the lever 150. This causes the rocker arm 146 to rotate about the pivot pin 144 in the direction of the arrow Gz (The elongate hole 70 is formed so that at this point of time, the brake lever 58 is not engaged with the ratchet wheel 38); (4) As a result, the pusher 138 of the second grip 136 is moved toward the receiver 124 of the first grip 120 so as to sandwich the seatbelt 18 therebetween; and (5) If the seatbelt 18 is pulled out under the circumstances, the pusher 138 and the receiver are move toward each other to more firmly sandwich or lock the seatbelt 18.

In such a conventional seatbelt retractor, friction may be developed between the rocker arm 146 and the pin 140 since the rocker arm 146 is in sliding engagement with the pin 140.

Due to such friction, a substantial force is required to rotate the second grip 136.

That is, the rocker arm 146 is rotated about the pivot pin 144, and the pin 140 is rotated about the shaft 134 when the seatbelt 18 is locked. At this time, sliding movement between the pin 140 and the inner surface of the recess 148 takes place within a range shown in Fig. 7.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the present invention to completely or substantially eliminate sliding movement between the recess of the rocker arm and the pin.

It is another object of the present invention to reduce friction between the rocker arm and the pin.

It is a further object of the present invention to reduce a force necessary to rotate the second grip so as to allow the second grip to smoothly rotate.

According to the present invention, there is provided a seatbelt retractor which comprises a frame including a pair of side walls and a rear wall extending between the side walls, a take-up reel extending between the side walls of the frame to take up a seatbelt, a first grip mounted to the rear wall of the frame to sandwich the seatbelt, a shaft extending between the side walls of the frame, a second grip having a support hole at its one end through which the shaft extends to pivotably support the second grip by the frame, the other or free end of the second grip being engaged with and disengaged from the frist grip, and an operating unit designed to move the second grip into engagement with the first grip under an emergent circumstance and including a pin extending from one side of the second grip and a rocker arm having at its front a recess in engagement with the pin, at least one of the pin and the recess being identical in shape to gear teeth.

Most preferably, the recess and the pin are both identical in shape to the teeth of gears. Alternatively, the recess and the pin may be similar in shape to the gear teeth.

Also, one of the recess and the pin may be identical in shape to the gear teeth.

With the seatbelt retractor of the present invention, the recess and the pin are engaged in the same manner as teeth of a pair of gears. In this way, sliding movement of the recess and the pin is completely or almost prevented. This arrangement prevents a friction which may occur when the pin is slid within the recess and also, allows the second grip to smoothly rotate.

Fig. 8 is a plan view of a pair of spur gears 501 and 502 rotatable about their respective centers 0i and 02. The spur gears have respective teeth 510 and 520. The teeth 510 and 520 have involute or cycloid surfaces 511 and 521 so that the both surfaces 511 and 521 may not be slid during rotation of the spur gears 5t1 and 502. This concept is applied to the recess of the rocker arm and the pin of the second grip in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing the principal part of a seatbelt retractor according to one embodiment of the present invention; Fig. 2 is a view showing the manner in which a pin is received in an elongate hole; Fig. 3 is a perspective view of a conventional seatbelt retractor; Fig. 4 is an exploded view of a reel lock mechanism; Fig. 5 is a vertical sectional view of the seatbelt retractor taken along the line m - m in Fig. 3; Fig. 6 is a perspective view of a guide and a first grip member; Fig. 7 is a sectional view showing the manner in which a rocker arm is engaged with a pin in the conventional seatbelt retractor; Fig. 8 is a plan view showing the manner in which spur gears are meshed with one another; and Figs. 9 and 10 are views of alternative embodiments of the present invention, showing the manner in which pins are received in recesses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With now reference to Figs. 1 and 2, the recess 148 has an involute inner peripheral surface 148N. Also, the pin 140 has involute opposite sides 140L received in the recess 148.

The pin 140 and the recess 148 are identical in contour to teeth 510 and 520 of gears 501 and 502 shown in Fig. 8 and are engaged with one another in the same manner as the gears 510 and 520. By this arrangement, when the rocker ann 146 is rotated about the pivot pin 144, and the second grip 136 is correspondingly rotated about the shaft 134, the inner surface 148N of the recess 148 and the sides 140L of the pin 140 are no longer slid relative to one another.

This eliminates friction which may occur when the pin 140 is slid within the recess 148 and also, allows the second grip 136 to very smoothly rotate.

In this embodiment, the pin 140 and the recess 148 are both involute in shape. Alternatively, they may have any shape, for example, cycloid, as far as they are identical in shape to the teeth of the gears. Still alternatively, they not necessarily have a curvature exactly identical to that of each gear, but may have a curvature similar to that of each gear.

In the present invention, the pin 140 may have a circular section whereas the inner surface 142N of the recess 148 have the same shape as shown in Fig. 9. As shown in Fig.

10, the inner surface 148N of the recess 148 may be flat, and the outer surface 140L of the pin 140 may be rounded.

In all of the foregoing embodiments, the pins 140 are in engagement with the recesses 148. Instead, an opening may be provided to receive the pin.

It will be noted that those like reference numerals used in Figs. 1, 2, 9 and 10 which are not described designate like elements used in Figs. 3 to 7.

Claims

What is claimed is:

1. A seatbelt retractor comprising: a frame including a pair of opposite side walls and a rear wall extending between said side walls; a reel shaft extending between said side walls of said frame and including an integral ratchet wheel; a take-up reel fit around said reel shaft to take up a seatbelt; a first grip mounted to said rear wall of said frame; a shaft extending between said side walls of said frame; a second grip having a support hole at its one end, said shaft being inserted into said support hole, whereby said second grip is pivotably supported by said frame, the other or free end of said second grip being engaged with and disengaged from said first grip; operating means for moving said second grip into engagement with said first grip under an emergent circumstance; and means for causing a brake lever to engage with said ratchet wheel under the emergent circumstance so as to lock said reel shaft; said operating means including a pin extending from one side of said second grip, and a rocker arm pivotably supported at its middle portion by said frame, said rocker arm having a front engagement portion engaged with said pin and a rear end movable by said ratchet wheel; at least one of said pin and said engagement portion being identical in shape to gear teeth.

2. A seatbelt retractor according to claim 1, wherein said gear teeth have involute surfaces.

3. A seatbelt retractor according to claim 1, wherein said gear teeth have cycloid surfaces.

4. A seatbelt retractor according to claim 1, wherein said rocker arm is pivotally connected at its rear end with one end of a lever, the other end of said lever is engageable with said ratchet wheel, whereby when the other end of said lever is brought into engagement with said ratchet wheel, said lever is pushed up to rotate said rocker arm so that said engagement portion of said rocker arm may push said pin to cause said second grip to move toward said first grip.