LOCKING DEVICE FOR A BAND IN A SAFETY BELT OF A PASSIVE VEHICLE SAFETY BELT SYSTEM

Abstract: A locking device for a band in a safety belt of a passive vehicle safety belt system comprises at least one fastening means (10) for the band (11) and a lock casing (15) into which the fastening means can be inserted and retained. The fastening means is adapted to be moved along a guide rail (13) by a traction means (16), controlled by an electric motor, and is adapted to be released from the traction means, when it engages with the lock casing, so that the traction means and the motor are not exposed to shock loads, when the fastening means engages with the lock casing. The traction means can continue its movement, when the power supply to the motor has been interrupted, so that the kinetic energy accumulated in the motor and the traction means can decay gradually. A slider (19) is attached to the traction means (16), and the fastening means (10) is releasably attached to the slider and is retained to the slider by means of pins (25, 31) and a pawl (36). The pawl is adapted to be released from the slider, when the fastening means is moved into the lock casing.

Description: Locking device for a band in a safety belt of a passive vehicle safety belt system Technical Field The present invention is related to a locking device for a band in a safety belt of a passive vehicle safety belt system. A passive vehicle safety belt system comprises a movable fastening means for the band in the safety belt; a guide rail for the movable fastening means attached to the car body; a power transmission means attached to the fastening means for moving the fastening means; and rever¬ sible motor means for driving the power transmission means for moving the fastening means backward and forward between a neutral position and a locking position on the guide rail. The locking device comprises a lock casing attached to the car body adjacent the guide rail at the locking po¬ sition of the fastening means for keeping the fastening means. The purpose of a passive vehicle safety belt system is to automatically attach a person, e.g. the driver, who takes a seat in the car, before the car is started. Background Art Passive vehicle safety belt systems of the type set forth above are previously known, for example through US Patent Specifications 3 830 518, 4 256 331, 4 345 781 and 4 354 696. An essential problem in the design of passive systems is the braking of the driving motor, normally an electric motor, used for moving the fastening means between the - neutral position and the locking position, when the faste¬ ning means is moved into the lock casing and stopped in the casing. The fastening means is stopped very abruptly in the lock casing by striking a stop surface, and this causes a heavy shock load on the power transmission means and the reversible motor means due to the kinetic energy ackumula- ted in the reversible motor means. This shock load can cau¬ se damage to the reversible motor means and the power transmission means leading to functional disorder and need of repair, and thus reducing the reliability of the system. The main object of the invention is to provide a lock¬ ing device for passive vehicle safety belt systems in which the locking of the fastening means in the lock casing can occur without exposing the reversible motor means and the power transmission means for any shock loads, so that the reliability is improved * . According to the invention this is obtained by means of a locking device having the features set forth in the claims. By the disconnection of the fastening means from the power transmission means, when the fastening means is moved into the lock casing, the power transmission means can move on a bit, until the movement of the reversible motor means has decayed. The electric driving motor can then easily be stopped by means of a microswitch that ' is positioned in the lock casing and actuated by the fastening means when the fastening means is moved into the lock casing. The kinetic energy accumulated in the reversible motor means including possible gear changing devices, for example worm gear units, can then decay successively during the continuing movement of the power transmission means in its previous path of motion. This will completely avoid any form of shock load on the motor means. Brief Description of Drawings One embodiment of the locking device according to the invention will now be further described below with referen¬ ce to the accompanying- drawings. Fig. 1 is a schematic view of a passive vehicle safety belt system having a movable fastening means for the band " of the safety belt; a guide rail for the fastening means with a lock casing for the fastening means; and driving means for the fastening means. Figs. 2-5 are longitudinal cross sections in a larger scale through the movable fastening means and its lock casing during the insertion of the fastening means in the lock casing. Fig. 6 is an end view of the lock casing with the fastening means inserted. Best Mode for Carrying Out the Invention The passive safety belt system shown in Fig. 1 compri- ses a movable fastening means 10 for a band 11 in a safety belt intended to be applied on a person sitting in the chair 12 in the car. Apart from the shown band 11, the safety belt comprises a support having a rotatable shaft for coiling the portion of the band not used. This support is positioned on the car floor adjacent the chair and attached to the car body. The support is provided with a band or vehicle sensitive locking device for automatical locking of the shaft. The support and the locking device can be of any type and have not been shown on the drawing for that reason. The fastening means 10 is movable along a guide rail 13 running substantially from the front pillar, the so called A-pillar, of the car body about horizontally backward to the rear pillar, the so called B-pillar, where it turns about 90* and runs downwards along the B-pillar to a position just above the head portion of the chair. At this position a lock casing 15 is provided to hold the fas¬ tening means 10. The lock casing surrounds the guide rail 13 and is rigidly attached to the pillar 14. The locking means and the lock casing will be described more in detail below with reference to Figs. 2-6. The fastening means 10 is attached to a power trans- misson means, designed as a punched ribbon 16 of well known type. The ribbon, -is driven by a reversible electric motor 17 over a cog wheel 18 for moving the fastening means along the guide rail between its end points 13A and 13B. The punched ribbon 16 runs in a guard rail, not shown, and can pull the fastening means from the end 13A to the end 13B of the guide rail and then push the fastening means back to the end 13A. The guide rail 13 has a substantially U-shaped cross section having leg flanges extending towards each other,, so that the guide rail has a substantially T-shaped channel, as shown in Fig. 6. The guide rail can preferably consist of an aluminium section. The fastening means 10 is attached to the punched rib¬ bon 16 by means of a slider 19, as shown in Fig. 2. The slider 19 is designed with a guide portion 20 that is sha- ped after the T-channel of the guide rail and movable in the guide rail in its longitudinal direction. The guide portion 20 is provided with a pivot 21 for engagement in a • hole 22 in the punched ribbon 16, so that the slider is moved when the punched ribbon is moved in the guide rail, and with a connection portion 23 projecting through a long¬ itudinal slot 24 of the guide rail 13. The connection por¬ tion 23, shown in Fig. 2 in front of the lock casing 15, is designed as a thin plate and is provided with a coupling pin 25, projecting on either side of the connection por- tion, at the edge 23A facing the lock casing. The connec¬ tion portion 23 is provided with a recess 26 in the edge 23B turned away from the lock casing. Furthermore, the con¬ nection portion is provided with a recess 27 in the edge 23C turned away from the guide rail. The recess 27 has a wall 28 forming a somewhat acute angle with the edge 23C. The fastening means 10 is designed as a loop having two parallel legs 29,30, as more clearly shown in Fig. 6, and is adapted to be connected to the connection portion 23 of the slider 19. The fastening means is for this purpose at the edge 10B which is turned away from the lock casing 15 provided with a projecting coupling pin 31 running bet¬ ween the legs 29,30 of the loop and adapted to engage with the recess 26 in the connection portion 23. The legs 29,30 of the loop are in its edges facing the lock casing provi-- ded with recesses 32 adapted to engage with the coupling pin 25 of the connection portion 23, and with slots 33 adapted to engage with a stationary edge 15A of the lock casing 15, when the fastening means is in its locking posi¬ tion. Furthermore, the fastening means 10 is at its edge 10B provided with a bent tap 34 adapted to engage with a wall 35 of the lock casing 15, so that the fastening means in the locking position is held at both edges 10A,10B in the lock casing. The fastening, means 10 is further provided with a pawl 36 movably mounted between the legs 29,30 of the fastening means substantially in the same plane as the plate-shaped connection portion 23 of the slider 19. The pawl is mounted by means of two projecting pivots 37,38. The first pivot 37 is adapted to engage with recesses 39 in the legs 29,30 of the fastening means, the areas of the recesses being sub¬ stantially larger than the cross section area of the.pivot, so that the pivot can be moved in the recesses. The second pivot 38 is adapted to engage with slots 40 in the legs 29,30. The slots 40 run substantially perpendicularly to the guide rail 13 and have a width corresponding to the thickness of the pivot projecting into the slots, so that the pivot can be guided in the slots. Due to the shape of the recesses 39 and the slots 40, the_ pawl 36 can be moved between the legs 29,30 towards and away from the connection portion 23 of the slider. The pawl is loaded by a leaf spring 41, attached between two pins 42,43, towards the connection portion 23 of the slider 19, so that the pawl normally abuts the connection portion. The pawl is provided with a projecting tooth 44, adapted to engage with the recess 27 of the connection portion 23, and with a projec¬ ting rear portion 45. Furthermore, the pawl has inclined guide surfaces 36A,36B facing the guide rail 13. The opera¬ tion of the guide surfaces will be described below. The loop forming the fastening means 10 is provided- with a recess 46 in its base portion. An eye 47 of the band 11 penetrates into the loop and is kept .in the loop by means of a shaft 48 attached to the loop and passing through the eye. The eye 45 is made by folding the end of the band and attaching the end to the band by means of seams 49. The lock casing 15 is provided with a slot-shaped recess 50 at the end facing the fastening means 10. The recess 50 is terminated by the crossing edge 15A and is for the rest limited by longitudinal edges 51 having indenta- tions 52 for engagement with the ends of the pivot 38 of the pawl 36, as will be further explained below. The recess 50 has a width so that the fastening means 10 can be moved into the recess, until the fastening means engages with the edge 15A. The lock casing 15 has a height so that the sli¬ der can be moved through the lock casing after having been released from the fastening means. The operation of the locking device described with reference particularly to Figs. 2 and 6 will now be explai- ned with reference to Figs. 1-5. In Fig. 2 the fastening means 10 and the slider 19 are shown outside the lock casing 15. If the punched ribbon 16 is moved to the left in the figure, the slider 19 will be moved towards the neutral position for the fastening means 10. The slider 19 drives the fastening means 10 by means of the coupling pin 25 and the recess 26 cooperating with the recess 32 and the coupling pin 31, respectively, of the fastening means. If the punched ribbon 16 is moved to the right in the figure, the slider 19 will be moved into the lock casing. The pawl 36 of the fastening means engages with the recess 27 of the slider 19 and drives the faste¬ ning means 10. During these movements of the slider 19 the fastening means is kept on the slider by means of the coup¬ ling pins 25,31 engaging with the recesses 32 and 26, re- spectively. When the slider 19 is pulled into the lock casing 15, the fastening means 10 will be moved into the recess 50. The pawl 36 will then abut the edge 15A of the lock casing with, its guide- surface 36A, as. shown in Fig. 3. When the slider and the fastening means are further pulled into the lock casing, the pawl will be lifted, the pivot 37 of the pawl being moved in the recess 39 in the fastening means and the rear portion 45 of the pawl being forced to abut the edge 23C of the connection portion of the slider, as shown in Fig. 4. Thus, the slider 19 is released from the fastening means 10 and can continue its movement through the lock casing 15. When the slider has been pulled away, the rear portion 45 of the pawl will fall down behind the slider. The pivot 38 of the pawl 36 is then moved in the slot 40 in the fastening means 10 and is moved into the recesses 52 in the lock casing by the action of the spring 41, as shown in Fig. 5. This will prevent unintentional withdrawal of the fastening means from the lock casing. The fastening means is now kept in the lock casing by the edge 15A of the lock casing engaging with the slot 33 of the fastening means, as shown in Figs. 4 and 5, and by the tap 34 of the fastening means.engaging under a wall 35 of the lock casing 15, as shown in Fig. 6. Thus, the lock casing will take up the possible stresses appearing in the band 11 of the safety belt. When the slider 19 is moved in opposite direction, the slider will first abut against the guide surface 36B of the rear portion 45 of the pawl. The rear portion 45 of the pawl is then lifted, so that the ends of the pivot 38 will be moved out of the recesses 52 in the lock casing and the fastening means can be moved out of the lock casing 15 by the slider 19. The pawl 36 will then again engage with the recess 27 in the slider. The fastening means 10 can preferably be provided with means for manual lifting of the pawl 36, so that the fas¬ tening means can be released from the slider, in case the automatic movement of the slider 19 is out of order for one reason or another. The fastening means can then be released from the slider 19 and manually inserted into the lock casing, so that the safety belt can be used, or manually withdrawn from the lock casing, so that a person embraced by the safety belt can be released. The locking device according; to the invention has been described above in connection w-i^th -a passive system of two-point-type. However, the locking device can as well be used in passive systems of three-point-type, for example in systems having two movable fastening means of the type shown in the U S Patent Specification 3 830 518 mentioned in the introductory portion. According to the invention, in such systems both fastening means must be released from the power transmission means, when they have been moved into their respective lock casings. The power transmission means must also after the insertion of the last fastening means in its lock casing continue its movement, so that the kine¬ tic energy ackumulated in the reversible motor means can decay gradually during the continued movement of the power transmission means, when the power supply to the driving motor has been interrupted. In such systems one fastening means can be driven and guided by the other fastening means. Thus, one fastening means is connected to the power transmission means over the other fastening means. While only one embodiment of the locking device accor¬ ding to the invention has been described and shown, it is evident that many variations and modifications are possible within the scope of the invention. The slider and the fas- tening.means can for example be designed in many different ways, and the coupling between these means can also be modified in many ways. For example, it is not necessary that the slider is completely released from the fastening means. In many cases it may be sufficient that the slider can be displaced slightly in relation to the fastening means, when this has been placed in its locking position. This can be accomplished by making the projections provi¬ ding the coupling on the fastening means and the slider, respectively, engage with elongated slots in the opposite means, so that a certain relative movement can occur. This may be an advantage, when it is not desirable to make the fastening means disconnectable, e.g. to ensure that the safety belt is used in a proper way.

Claims: Claims 1. Locking device for a band in a safety belt of a passive vehicle safety belt system which comprises at least one movable fastening means (10) for the band (11); a guide rail (13) attached to the car body for guiding each movable fastening means; a power transmission means (16) for moving each movable fastening means; and reversible motor means (17,18) for driving the power transmission means for moving each fastening means forward and backward between a neutral position (13A) and a locking position (13B); comprising a lock casing (15) for each fastening means which is attached to the car body adjacent the guide rail (13) at the locking position (13B) of the respective fastening means and into which the fastening means can be inserted and kept, charac¬ terized in that each fastening means (10) is adapted to be released from the power transmission means (16) when inser¬ ted into its lock casing (15) and in that the power trans¬ mission means (16) can continue its movement after the release of the last fastening means and interruption of the power supply to the motor means (17,18), so that the kine- tic energy ackumulated in the reversible motor means can decay gradually during the continued movement of the pover transmission means. 2. Locking device according to cairn 1, characterized in that a slider (19) is attached to the power transmission means (16) and adapted to be moved in the guide rail (13) and in that each fastening means (10) is adapted to be releasably connected to the slider (19). 3. Locking device according to claim 2, characterized in that the slider (19) has a connection portion (23) projec- ting from the guide rail (13) through a longitudinal slot (24) in the rail and in that at least one fastening means (10) is adapted to be attached to this connection portion (23) and to be moved along the guide rail (13) at the out¬ side of the rail. 4. Locking device according to claim 3, characterized in that the fastening means (10) is attached to the connection portion (23) of the slider (19) by means of two projections (25,31), one of which (25) being provided on the connection portion (23) of the slider and adapted to engage with a recess (32) in the edge (10A) on the fastening means (10) facing the lock casing when the fastening means is moved towards the lock casing (15), and the other (31) being pro¬ vided on the fastening means (10) and adapted to engage with a recess (26) in the edge (23B) on the connection por¬ tion (23) of the slider turned away from the lock casing when the slider is moved towards the lock casing (15), so that the slider (19) and the fastening means (10) can be brought into and out of engagement with each other by rela- tive movement in the longitudinal direction of the guide rail (13) and so that the slider (19) when moved towards the neutral position (13A) of the fastening means (10) dri¬ ves the fastening means and when moved away from the neut¬ ral position of the fastening means may be released from the fastening means, and in that a movable pawl (36) is provided to keep the fastening means (10) at the connection portion (23) of the slider, when the slider (19) is moved away from the neutral position (13A) of the fastening means, and to release the connection portion (23) of the slider, when the fastening means (10) has been inserted into the lock casing (15). 5. Locking device according to claim 4, characterized in that the pawl (36) is movably mounted on the fastening means (10) in the same plane as the connection portion (23) of the slider (19) and is provided with a projecting tooth (44) adapted to engage with a recess (27) in the connection portion (23) of the slider to keep the fastening means (10) at the connection portion (23) of the slider during the movement of the slider (19) towards the lock casing (15), and a projection (38) adapted to engage with a stationary portion (51) of the lock casing to prevent withdrawal of the fastening means from the lock casing, when the connec- tion portion (23) of the slider has been released from the fastening means (10). 6. Locking device according to claim 5, characterized in that the pawl (36) is provided with two projecting pivots (37,38) and the fastening means (10) is 5 provided with two recesses (39,40) with which the pivots of the pawl can engage, one recess (39) having an area sub¬ stantially larger than the cross section area of the pivot (37) penetrating the recess, so that the pivot (37) can be moved in the recess (39), and the other recess (40) forming a slot running substantially perpendicularly to the guide rail (13) and having a width corresponding to the thickness of the pivot (38) penetrating the recess, so that the pivot (38) is guided in the slot during the movement of the pawl (36). 7. Locking device according to claim 6, characterized in that the fastening means (10) is provided with a spring (41) adapted to force the pawl (36) in a direction towards the guide rail (13). 8. Locking device according to claim 7, characterized in that the fastening means (10) is provided with a recess (33) in the edge (10A) facing the lock casing when the fas¬ tening means is moved into the lock casing, the recess (33) being adapted to cooperate with a stationary portion (15A) of the lock casing (15), so that the fastening means (10) is hold at the lock casing at this edge (10A), and that the fastening means (10) at its opposite edge (10B) is provided with a projection (34) adapted to be moved into the lock casing (15) and retained by a rigid portion (35) of the lock casing (15), so that, the fastening means (10) is held in the lock casing also at this edge (10B).. 9. Locking device according to claim 8, characterized in that the lock casing (15) is provided with a control surfa¬ ce (15A) for the pawl (36), so that when the fastening means (10) is moved into the lock casing (15) the pawl is moved away and releases the connection portion (23) of the " slider, so that the slider (19) may be pulled away from the fastening means by the power transmission means (16), and with a recess (52) for the pivot (38) positioned in the the slot-shaped recess (40) in the fastening means, the pivot (38) being adapted to be moved into the recess (52) to retain the fastening means (10) in the lock casing (15), when the slider has been released from the fastening means (10). 10. Locking device according to any of the preceding claims, characterized in that each fastening means (10) and its lock casing (15) are so designed that each fastening means can be inserted manually into its lock casing to be retai- ned in the casing.

Inventors: MOERNER BENGT OLOF JOHAN STELL, MOERNER, BENGT, OLOF, JOHAN, STELLAN
Applicants: AUTOLIV DEV, AUTOLIV DEVELOPMENT AKTIEBOLAG
Application year: 1985
Main classification: B60R22
IPC codes: B60R22