GB2236662A - Seat belt retractor with locking means - Google Patents

Abstract

A seat belt retractor and belt assembly includes an actuating member 28, 3a, 29 provided on the seat belt 3 for actuating seat belt locking means 20, 21 normally actuated by emergency rotation of the seat belt reel, when a seat belt 3 has been withdrawn fully or substantially fully from the reel on which it is wound. Load upon the seat belt reel is thus prevented when the seat belt is won fully extended from the reel eg due to a large occupant and the reel is unable to rotate enough to actuate the locking means (20, 21) in the normal manner. <IMAGE>

Description

- f SEAT BELT RETRACTOR This invention relates to a seat belt retractor

which locks a seat belt against extraction at prescribed times such as when the seat belt is pulled out suddenly or when sudden acceleration occurs.

In order to protect a passenger in an automotive vehicle in an emergency situation such as when the vehicle is involved in a collision, a seat belt apparatus is installed at the seat of the vehicle. It is so arranged that the seat belt in such a seat belt apparatus is taken up by an emergency locking-type retractor device attached to a reinforced member of the vehicle body- When the passenger has fastened the seat belt, ordinarily the seat belt can pulled out of the retractor device freely so that passenger movement will not be restrained. On the other hand, when an emergency situation such as a collision occurs, an impact force or sudden deceleration is sensed, thereby actuating reel shaft locking means to halt the rotation of the reel shaft about which the seat belt has been wound. By thus locking the reel shaft against rotation, the seat belt restrains the passenger to prevent sudden movement of the passenger and protect against injury.

Though the reel shaft locking means is capable of reliably halting rotation of the reel shaft upon which 2 the seat belt has been wound, there are occasions where an excess amount of the seat belt that has been taken up on the reel shaft is pulled out owing to tightening of the seat belt, despite the fact that rotation of the reel shaft has been halted. In order to prevent this extraction of the seat belt owing to the tightening thereof, a seat belt retractor of the kind shown in Fig. 8 has been proposed.

As shown in Fig. 8, the seat belt retractor, designated by numeral 101, comprises a pendulum 103 attached to a frame 102 and adapted to tilt when acted upon by an impact force in excess of a predetermined value, a ratchet 105 secured coaxially on a reel shaft (not shown) which takes up a seat belt 104, a link 106 actuated by tilting of the pendulum-103 to engage a pawl 106a with a tooth of the ratchet 105 so as to be moved uDward bv the turning force of the ratchet 105, and a stop member 108 turnably attached to the frame 102 and turned by upward movement of the link 106 to clamp the seat belt 104 between itself and a wall member 107.

In accordance with this seat belt apparatus 101, the stop member 108 clamps the seat belt 104 per se against the wall member 107 at the occurrence of an emergency, as a result of which extraction of the seat belt 104 due to tightening can be prevented.

Depending upon the body build of the passenger, there are cases where the seat belt 104 is fastened in the fully extracted state. When an emergency such as a 3 collision occurs under such a condition, the seat belt 104 is incapable of pulling out any further since it is already fully extracted. Consequently, since the reel shaft upon which the seat belt 104 has been wound and the ratchet 105 do not rotate, the stopper member 108 does not turn and the seat belt 104 is not clamped by the stop member 108. Accordingly, the force acting upon the seat belt 104 is transmitted directly to the reel shaft which, as a result, is subjected to a large load. This means that the reel shaft must be formed of a highly rigid material, such as steel. The result is that the seat belt retractor 101 is heavy and comparatively expensive to manufacture.

1 An object of the present invention is to reliably is prevent extraction of a seat belt at occurrence of sudden deceleration and when the seat belt is suddenly pulled in a case where the seat belt has-been fastened with a surplus amount thereof left wound upon a reel shaft.

Another object of the present invention is to prevent a large load from being applied to a reel shaft by movement of a passenger when the seat belt restraining the passenger has been pulled out fully or substantially fully.

According to the present invention, the foregoing objects are attained by providing a seat belt retractor comprising a seat belt wound upon a reel shaft so as to 4 be freely taken ui thereon or extracted therefrom, and seat belt locking means for locking the seat belt against extraction at a predetermined time, the seat belt being provided with an actuating member for the seat belt locking means for actuating the seat belt locking means when the seat belt has been extracted fully or substantially fully.

In the seat belt retractor of the invention constructed as set forth above, the actuating member actuates the seat belt locking means when the seat belt has been extracted fully or substantially fully, as a result of which the seat belt is locked against extraction. Accordingly, a large load from the seat belt will not act upon the reel shaft and therefore the 16 reel shaft need not exhibit that much rigidity. This makes it possible to form the reel shaft of a light weight, inexpensive material such as resin. In addition, forming the reel shaft of a light-weight material makes possible a reduction in the weight and manufacturing cost of the overall seat belt retractor.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the following descr.ption-and the accompanying cliims.

The invention is illustrated by way of example in the drawings, in which:

Fig. 1 illustrates an embodiment of a seat belt retractor according to the present invention, in which (a) is a front view of the embodiment, (b) a side view of the embodiment, and (c) a sectional view taken along line Ic-Ic in Fig. 1(a); Fig. 2 is an exploded perspective view of the embodiment, in which (a) is a view mainly showing the principal components of a retractor and (b) a view mainly showing seat belt locking means; Fig. 3 is shows a flywheel, a spring member and a frictional locking member in an assembled state, in which (a) is a front view and (b) a sectional view taken along line IIIb-IIIb in Fig. 3(a); Fig. 4 is a view showing, in enlarged form, a seat is belt placed in a locked state by actuating the seat belt locking means at a predetermined time; Fig. 5 illustrates the state of the seat belt locking means when the seat belt is fully extracted or substantially fully extracted, in which (a) is a view showing, in enlarged form, a seat belt placed in a locked state by actuating the seat belt locking means, and (b) is a view as seen from the direction of arrow A in Fig. 5(a); Fig. 6 illustrates another embodiment of the present invention, in which (a) is a view similar to that of Fig. 5(a), (b) is a sectional view of a sliding clamping member used in this embodiment, and (c) is a 6 view showing a through-hole in the seat belt; Fig. 7 is a view illustrating another embodiment of the present invention and is similar to Fig. 5(a); and Fig. 8 is a perspective view showing a seat belt retractor according to the prior art.

Embodiments of the present invention will now be described with reference to the drawings.

As shown in Figs. 1(a) through (c), a seat belt retractor 1 according to the present invention includes a case 2, a reel shaft 4, which is supported substantially at the central portion of the case 2, for freely paying out and taking up a seat belt 3, and seat belt locking means 5 provided above the reel shaft- 4 for locking the seat belt 3 against extraction from the reel is shaft 4.

A decelaration sensor 6 responsive to sudden deceleration is attached- to the lower part of the case 2 on one side face 2a thereof. The deceleration sensor 6 comprises a supporting case 6a, a cask-shaped inertial body 6b placed on the supporting case 6a and adapted to be tilted by the action of acceleration approximately in the horizontal direction, and an actuator 6c rotatively displaced in a vertical plane in response to tilting of the inertial body 6b. The actuator 6c has a free end 6d adapted to engage the ratchet 7a, which is formed on the outer periphery of a flywheel 7, when the actuator 6c has been rotatively displaced.

7 Connected to the other end of the reel shaft 4 is one end of a restoration spring 8, whose other end is fixed to another side face 2b of the case 2. Accordingly, the arrangement is such that the seat belt 3 is pulled off the reel shaft 4 against the biasing force and taken up on the reel shaft 4 by the biasing force of the restoration spring 19.

Fig. 2 is an exploded perspective view of the embodiment, in which (a) is a view mainly showing the principal components of a retractor main body and (b) a view mainly showing seat belt locking means 5.

As shown in Fig. 2, a ratchet wheel 9 is integrally attached to one end of the reel shaft 4 so as to be coaxial therewith.

A projection 9a coaxial with the reel shaft 4 is formed on the outer side of the ratchet wheel 9, which is secured to one end of the reel shaft 4. Loosely fitted on the projection 9 are a tie plate 10 via a through-hole 10a formed in one end portion thereof, and a locking ring 11, the inner circumferential surface of which is formed to have inner teeth 11b, via a through-hole lla formed in its central portion. A spring member 12 is interposed between a spring hanger 10b, which is provided on the approximate central portion of the tie plate 10, and a spring hanger llc provided on the locking ring 11. A biasing force for turning the locking ring 11 in the direction of arrow A1 is applied to the locking ring 11 at all times 8 by the spring member 12. The tie plate 10 is fixed by virtue of a pivot pin 13 passing through an insertion hole 10c formed in the other end portion of the tie plate 10. A substantially columnar reel member 14 upon which the seat belt 3 is wound is fitted over the reel shaft 4.

A hook retainer 15 is secured to the projection 9a of the ratchet wheel 9 situated on the outer-side of the locking ring 11. A support pin 15a extending parallel to the axis of rotation of reel shaft 4 is provided on the peripheral portion of the hook retainer 15, and a hook 16 is disposed on the hook retainer 15 by being pivotally supported on the support pin 15a so as to be capable of rocking back and forth. A compression coil spring 17 is interposed between the hook retainer 15 and the hook 16 and biases the hook 16 so as to turn about the support pin 15a in the direction of arrow Bl.

A pawl 16a capable of engaging the inner teeth 11b of locking ring 11 is formed on a portion of the outer periphery of hook 16, and a connecting pin 16b is formed on the hook 16 on the end thereof that rocks about the support pin 15a. Accordingly, owing to the biasing of hook 16 by the compression coil spring 17, the pawl 16a ordinarily is spaced away from the inner teeth llb.

The connecting pin 16b is fitted through a locking hole 18a provided in the outer periphery of a frictional locking member 18 formed to have a generally ring-shaped configuration. The inner periphery of the frictional 9 locking member 18 is provided with a cut-out portion 18b into which the support pin 15a protrudes upon being passed through the hook 16. The flywheel 7 formed to have the ratchet 7a on its outer circumferential surface is frictionally engaged with the outer periphery of the frictional locking member 18 via a spring member 19.

Figs. 3(a), (b) are views illustrating the spring member 19, the frictional locking member 18 and the flywheel 7 in the assembled state.

As shown in Figs. 3(a), (b), the inner side of the flywheel 7 is formed to have a plurality of spring member retainers 7b equidistantly spaced in the circumferential direction and projecting inwardly toward the center of the flywheel. Spacing H between the retainers 7b and a side wall 7c is set to be approximately the same as the combination of the thickness of frictional locking member 18 and the diameter of the wire material constituting the spring member 19, and the outer diameter of the ring of spring member 19 is set to be approximately the same as the inner diameter I of flywheel 7. As a result, these components can be assembled in the state shown in Figs. 3(a), (b). Further, one end 19a of spring member 19 is anchored in a spring member fastener 18c formed in one side face of the frictional locking member 18.

As shown in Figs. 1(c) and 2(b), the seat belt locking means 5 comprises a sliding clamp member 20 attached to the case 2 so as to be capable of sliding in - the directions in which the seat belt 3 is pulled out and taken up, and a turning clamp member 21 disposed opposite the sliding clamp member 20 for clamping and locking the seat belt 3 when actuated.

The sliding clamp member 20 comprises a clamping member 20a attached to the case 2 so as to be capable of sliding in the directions in which the seat belt 3 is pulled out and taken up (the Z direction), an abutting member 20c retained by the clamping member 20a and formed to have a corrugated portion 20b on a surface which contacts the seat belt 3, and biasing members 20d, 20d which bias the clamping member 20a downwardly in the Z direction at all times.

The turning clamp member 21 is turnably supported on a shaft 22 spanning both side faces 2a, 2b of case 2, and an end thereof which contacts the seat belt 3 is formed to have a corrugated portion 21a. When the turning clamp member 21 turns in the D1 direction, the seat belt 3 is strongly clamped between the clamp member 21 and the sliding clamp member 20. Further, a screw hole 21c is formed in one side face 21b of the turning clamD member 21.

One corner of a triangularly shaped link member 24 is rotatably connected by a screw 25 to the screw hole 21c via a spacing member 23 passed through an arcuate slot 2c formed in one side face 2a of case 2. One of the other two corner portions of link member 24 is turnably attached to the side face 2a of case 2 by a pin 26. The link member 24 is provided with a projecting pin 24a in the proximity of its remaining corner portion, and one end of a locking member 27 is turnably attached to the pin 24a. 5 A guide pin 27a projects from the other end of the locking member 27 and is inserted into a guide hole 11d of the locking ring 11. Since the locking ring 11 is biased in the A1 direction by the spring member 12 at all times, a distal end 27b of the locking member 27 ordinarily is in a position where it is spaced away from the ratchet wheel 9. When the locking ring 11 is turned in the A2 direction against the biasing force of the spring member 12, the distal end 27b of the locking member 27 is in a position where it engages the ratchet wheel 9.

The operational relationship among the flywheel 7, locking ring 11, hook retainer 15, hook 16 and frictional locking member 18 will now be described. The arrangement is such that when the seat belt 3 wound upon the reel shaft 4 is pulled, the ratchet wheel 9, hook retainer 15, hook 16, frictional locking member 18 and flywheel 7 turn together in the A2 direction about the rotational axis of reel shaft 4.

Further, the arrangement is such that when the seat belt 3 is pulled at ordinary speed, the hook 16, frictional locking member 18 and flywheel 7 turn together at the same speed, though the hook 16 does not turn about the pin 15a of hook retainer 15. In other 12 - words, it is so arranged that the pawl 16a of hook 16 will not engage the inner teeth llb of locking ring 11 and so that the locking ring 11 will not turn in the A2 direction, as a result of which the locking member 27 5 will not engage the ratchet wheel 9.

In a case where the acceleration sensor 6 is actuated to cause the free end of the actuator 6c to engage the ratchet 7a of flywheel 7, the flywheel 7 and the frictional locking member 18 no longer turn.

Therefore, the hook 16 turns in the B2 direction about the pin 15a and the pawl 16a engages the inner teeth lib of the locking ring 11, whereby the locking ring 11 turns in the A2 direction. As a result, the locking member 27 engages the ratchet wheel 9. Accordingly, the rotation of the reel shaft 4 is transmitted to the link member 24 via the ratchet wheel 9 and locking member 27, thereby turning the link member 24 about the pin 26. owing to this turning motion of the link member 24, the turning clamp member 21 turns in the D1 direction to strongly clamp the seat belt 3 between itself and the sliding clamp member 20. As a result, the seat belt 3 cannot be pulled out.

In a case where the seat belt 3 is pulled suddenly, relative rotation develops between the frictional locking member 18 and the hook retainer 15 owing to the inertia delay of the flywheel 7 and frictional locking member 18, as a result the hook 16 which is connected to the frictional locking member 18 and also supported on the pin 15a so as to be capable of locking back and forth turns in the direction of B2 about the pin 15a against bias force of the spring 17. When this takes place, the hook 16, locking ring 11 and locking member 27 behave in exactly the same manner as when the acceleration sensor 6 was actuated.

As shown in Figs. 1(c) and 2(a), a through-hole 14a of a predetermined size is formed in the portion of the reel member 14 upon which the seat belt 3 is wound. As depicted in Figs. 1(c) and 5(b), the seat belt locking means 5 has an actuating button 28, which projects to a predetermined height, secured to a portion at which the seat belt 3 starts to be wound. The button 28 is situated centrally of the seat belt in the width direction thereof. The arrangement is such that the actuating button 28 just fits into the through-hole 14a when the seat belt is taken up on the reel member 14.

As a result, owing to the actuating button 28, the portion of the seat belt 3 taken up will not protrude indiscriminately and the seat belt takeup operation can proceed smoothly. When the seat belt 3 has been pulled out fully or substantially fully, the actuating button 28 abuts against the tip of the turning clamp member 21 and causes the latter to turn, thereby clamping the seat belt 3. The operation of the seat belt retractor 1 in this embodiment thus constructed will now be described. 25 First, under ordinary conditions, the seat belt 3 is wound up upon the reel shaft 4 owing to the biasing force of the restoration spring 8. When the seat belt 3 is pulled at usual speed in order to fasten the seat 14 - belt, the hook 16, frictional locking member 18 and flywheel 7 turn together at the same speed in the A2 direction. Consequently, the hook 16 turns about the pin 15a of hook retainer 15 so that the pawl 16a of hook 5 16 does not engage the inner teeth lla of locking ring 11. Accordingly, the locking ring 11 does not turn in the A2 direction and the locking member 27 does not engage the ratchet wheel 9. As a result, the seat belt 3can be pulled out freely at ordinary speed.

When a large deceleration is produced by an emergency situation such as a collision, the deceleration sensor responds to this deceleration and causes the free end 6d of actuator 6c to engage the ratchet 7a of flywheel 7. Consequently, the fly%,fneel 7 and frictional locking member 18 can no longer turn and therefore relative rotation occurs between the hook 16 and frictional locking member 18, the hook 16 turns in the B2 direction about the pin 15a, and the pawl 16a engages with inner teeth llb of the locking ring 11. As a result, the locking ring 11 turns in the A2 direction and therefore the locking member 27 turns and engages the ratchet wheel 9. Owing to the engagement between the locking member 27 and the ratchet wheel 9, the turning force of the ratchet wheel 9 is transmitted to the turning clamp member 21 via the locking member 27 and link member 24. Consequently, the turning clamp member 21 turns in the D1 direction so that the corrugated portion 21a at the end thereof engages the seat belt 3 to clamp the seat belt between itself and the sliding clamp member 20. Though the seat belt 3 attempts to pull out owing to the inertia of the passenger wearing the seat belt, the clamping force of the turning clamp member 21 is increased by the force attempting to pull out the seat belt 3, as a result of which the seat belt 3 is clamped more strongly. Accordingly, the seat belt 3 is locked against any further extraction. Thus, pull-out of the seat belt 3 is prevented with certainty and the passenger is restrained in reliable fashion. Moreover, since the force acting upon the seat belt 3 owing to the inertia of the passenger is not transmitted to the reel shaft 4, tightening of the seat belt 3 on the take-up portion of the reel shaft is reliably prevented.

In a case where the seat belt 3 is pulled out suddenly by sudden movement of the passenger, the ratchet wheel 9 turns abruptly. Owing to an inertial delay of the flywheel 7 and frictional locking member 18, a rotational delay develops between the frictional locking member 18 and hook 16, and relative rotation occurs between the flywheel 7 and the frictional locking member 18 and hook 16. As a consequence, the hook 16 turns in the B2 direction about the pin 15a. When the hook 16 turns in the B2 direction, the hook 16, locking ring 11 and locking member 17 behave in exactly the same manner as when the acceleration sensor 6 was actuated.

Accordingly, the turning clamp member 21 locks the seat 16 - belt 3 between itself and the sliding clamp member 20 so that the seat belt 3 can no longer be pulled out. As a result, the passenger is restrained with certainty and tightening of the seat belt 3 can be prevented in a 5 reliable manner.

In a case where the seat belt 3 is fastened by a passenger in a state where the seat belt is fully or substantially fully extracted owing to the large body build of the passenger, the actuating button 28 secured to the seat belt 3 abuts against the tip of the turning clamp member 21, as shown in Figs. 5(a), (b), thereby turning the clamp member 21 in the D1 direction. Accordingly, the seat belt 3 is strongly clamped between the turning clamp member 21 and the sliding clamp member 20 and will be pulled out no further.

As a result of the foregoing, the force applied to the seat belt 3 is not transmitted to the reel shaft 4, and therefore the reel shaft is not subjected to a large load. This means that the reel shaft 4 need not have that much rigidity. Accordingly, heavy steel employed in the conventional arrangement need not be used for the reel shaft 4. Instead, a lightweight, inexpensive material such as resin can be used.

Fig. 6 illustrates another embodiment of the present invention, in which structural elements identical with those of the foregoing embodiment are designated by like reference characters and need not be described again.

17 In this embodiment, as shown in Fig. 6, an end 3a of the seat belt obtained by folding the seat belt over on itself is utilized as an actuating member which actuates the turning clamp member 21 when the seat belt 3 is pulled out fully or substantially fully. More specifically, in order to anchor the seat belt 3 to the reel shaft 4, as shown in Fig. 1(c), the end portion of the seat belt 3 is folded over on itself as in the prior art but, by extending the folded portion, the end 3a of the seat belt 3 is made to actuate the sliding -clamp member 20 when the seat belt 3 is pulled out fully or substantially fully. In other words, a flange 20e on the lower end of clamping member 20a of sliding clamp member 20 is made to project by a large amount, and the flange 20e is formed to have a slot 20f through which the seat belt 3 is passed, as shown in Figs. 6(b) and (c). The slot 20f is designed to have dimension a somewhat larger by an amount a than the thickness of the seat belt 3 so that the seat belt is capable of sliding freely in the slot 20f. When the seat belt 3 is pulled out fully or substantially fully, the end 3a of the seat belt abuts against the flange 20e so that the sliding clamp member 20 is slid upwardly in the Z direction from the position of the two-dot chain line to the position of the solid line. Owing to this upward movement of the sliding clamp member 20, the flange 20e abuts against the tip of the turning clamp member 21, whereby the latter is turned in the D1 direction. As a result, the 18 - seat belt 3 is clamped and locked between the sliding clamp member 20 and the turning clamp member 21. In this case, it is required that the size of slot 20f be.suitably designed in conformity with the seat belt 3 in order to assure the engagement between the edge 3a of seat belt 3 and the sliding clamp member 20. In this embodiment, the actuating button 2 of the foregoing embodiment is not required.

Fig. 7 is a view illustrating yet another embodiment of the present invention, in which structural elements identical with those of the foregoing embodiment are designated by like reference characters and need not be described again.

In this embodiment, as shown in Fig. 7, a comparatively large thread stitched into seat belt 3 is utilized as an actuating member which actuates the turning clamp member 21 when the seat belt 3 is pulled out fully or substantially fully. ^With this arrangement, the seat belt 3 need not be folded upon itself, and therefore less material for the seat belt suffices. In this case, it is required that the size of the slot 20f be appropriately designed in order to assure engagement between the sliding clamp member 20 and the thread 29.

Thus, in accordance with the seat belt retractor of the present invention as described above, when the seat belt is pulled out fully or substantially fully, the seal belt locking means actuating member provided on the 19 - seat belt actuating the seat belt locking means. Therefore, when the seat belt is pulled out fully or substantially fully, the seat belt is reliably locked against extraction. Accordingly, a large load from the seat belt will not act upon the reel shaft and therefore the reel shaft need not exhibit that much rigidity. This makes it possible to form the reel shaft of a light-weight, inexpensive material such as resin. In addition, forming the reel shaft of a light-weight material makes possible a reduction in the weight and manufacturing cost of the overall seat belt retractor.

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Claims (6)

1. A seat belt retractor comprising: a seat belt wound upon a reel so as to be freely taken up thereon or withdrawn therefrom; and seat belt locking means for locking said seat belt against withdrawal; said seat belt being provided with an actuating member for engaging and actuating said seat belt locking means when said seat belt has been fully or substantially fully withdrawn from said reel.

2. A seat belt retractor according to claim 1, wherein said actuating member is an actuating button attached to said seat belt.

3. A seat belt retractor according to claim 1, wherein said actuating member is an edge of said seat belt on an end thereof attached to.said reel.

4. A seat belt retractor according to claim 1, wherein said actuating member is a thread stitched into said seat belt.

5. A seat belt retractor according to claim 1 substantially as described herein with reference to the accompanying drawings.

Published 1991 at The Patent office, Statel-i.use. 66171 High Holborn. London WC I R 47P. Further copies may be obtained from Sales Branch. UTIAL

6. Nine Mile Point, Cu-rnfelinfch, Cross Keys. Nckport. NPI 7HZ. Printed by Multiplex techniques lid. St Mary Cray. Kent-