MECHANICAL PRE-TENSIONING DEVICE FOR A SEAT BELT

Abstract

The invention relates to a pre-tensioning device (27) for a seat belt comprising: - a carriage (28) intended to be mounted so as to be movable in translation relative to a structural element (15) between an inactive position and an active position, - a support (30) intended to be mechanically linked to a strap (23) of the seat belt (16) mounted on the carriage (28), said support (30) being movable between a locked position in which the support (30) blocks a translational movement of the carriage (28) relative to the structural element (15) and an unlocked position in which the support (30) allows a translational movement of the carriage (28) relative to the structural element (15), and - a first elastic member (31) mounted compressed between the structural element (15) and the carriage (28) when the support (30) is in the locked position.

Description

Title of the invention: MECHANICAL PRE-TENSIONING DEVICE FOR A SEAT BELT

[0001] The present invention relates to a mechanical pre-tensioning device for a seat belt. The invention finds a particularly advantageous application in the field of aeronautics, in particular with first class or business class type aircraft seats.

[0002] In a manner known per se, as illustrated in [Fig. 1a], an airplane seat 10 comprises a low structure 11 intended to be fixed in particular to rails of an airplane cabin by means of fasteners 12. The seat 10 also comprises a seat 13 carried by the low structure 11 as well as a backrest 15. In the case of a seat 10 of the first class or business class type, the seat 10 may comprise one or more actuators ensuring a pivoting of the backrest 15 around a horizontal axis towards the rear and, if necessary, a movement of the seat 13 towards the front so as to move the seat 10 from a seated position to a bed position in which the backrest 15 defines with the seat 13 a substantially horizontal lying surface so that a passenger 14 can lie down.

[0003] In order to ensure the safety of the passenger 14, the seat 10 may include a belt 16 called a "three-point belt" making it possible to ensure that the passenger 14 is restrained on the seat 10 in the event of an impact by means of three straps having three attachment points on the seat 10. More precisely, the three-point belt 16 includes a lap belt 17 formed by two straps 19 arranged on either side of the passenger 14. The straps 19 each have one end fixed to the lower structure 11 or to the seat 13 by means of a fastener 20. The two straps 19 are connected to each other by means of a belt buckle 21 so as to close the lap belt 17 around the body of the passenger 14.

[0004] The three-point belt 16 further comprises an upper strap 23 intended to hold the upper part of the body of the passenger 14. The upper strap 23 is wound around a locking reel 24 capable of locking the strap 23 when a force greater than a threshold is applied to the strap 23. The reel 24 is fixed on a rear face of the backrest 15. Alternatively, the reel 24 can be fixed on the lower structure 11 at the level of the rails of the aircraft cabin. The upper strap 23 coming from the reel 24 passes through a passage opening made in the upper part of the backrest 15, in particular at the level of the shoulder of the passenger 14. The upper strap 23 has at its end a fixing interface intended to cooperate with the belt buckle 21.

[0005] As illustrated in [Fig. 1b], during a significant impact, in particular during a crash, the head of the passenger 14 moves relative to the backrest 15, which results in a risk of injury in the event of contact with an obstacle 25 located in front of the seat 10 in the path of the head. The movement of the head is the result of several factors, namely: - the rigidity of the seat 10, mainly the low structure 11 and the backrest 15, - the elongation of the upper strap 23, - elongation of the ventral belt 17, - the locking time of the reel 24, and - the tension of the upper strap 23 inside the reel 24.

[0006] The invention aims to effectively remedy the aforementioned drawbacks by proposing a pre-tensioning device for a seat belt, comprising: - a carriage intended to be mounted mobile in translation relative to a structural element between an inactive position and an active position, - a support intended to be mechanically linked to a strap of the seat belt, said support mounted on the trolley being movable between a locked position in which the support blocks a translational movement of the trolley relative to the structural element and an unlocked position in which the support allows a translational movement of the trolley relative to the structural element, - a first elastic member mounted compressed between the structural element and the carriage when the support is in the locked position, - so that when a tensile force applied to the strap exceeds an activation threshold, the support moves into the unlocked position so as to allow decompression of the first elastic member providing a thrust on the carriage moving from the inactive position to the active position in order to apply a pretensioning force to the strap.

[0007] The invention thus makes it possible to reduce or even cancel out the effects of the aforementioned factors, namely the elongation of the upper strap, the elongation of the lap belt, the locking time of the reel, and the tension of the upper strap inside the reel (with the exception of the rigidity of the seat) in order to significantly limit the length of movement of the head during a crash. The invention further provides a simple solution with reduced development and production costs.

[0008] According to one embodiment of the invention, the support carries a winder around which the strap is wound.

[0009] According to one embodiment of the invention, the support is mounted to be movable in rotation relative to the carriage around a hinge between the locked position in which a protuberance of the support cooperates with a housing made in the structural element and the unlocked position in which the protrusion of the support is released from the housing made in the structural element.

[0010] According to one embodiment of the invention, a second elastic member urges the support into the locked position.

[0011] According to one embodiment of the invention, a calibration of the second elastic member defines an activation threshold of the pre-tensioning device.

[0012] According to one embodiment of the invention, a locking finger is capable of being stressed by an elastic member so as to extend projecting relative to a face of the structural element, said locking finger being intended to cooperate with a housing made in the carriage to block the carriage in the active position.

[0013] According to one embodiment of the invention, the locking finger comprises a beveled head.

[0014] According to one embodiment of the invention, said pre-tensioning device comprises a stop provided in the structural element to limit movement of the carriage in the active position.

[0015] According to one embodiment of the invention, said pre-tensioning device comprises a resetting screw cooperating with a threaded opening made in the stop.

[0016] According to one embodiment of the invention, the structural element is a seat back.

[0017] The invention also relates to a seat comprising a safety belt and a pre-tensioning device as previously defined.

[0018] The present invention will be better understood and other characteristics and advantages will become apparent upon reading the detailed description which follows, comprising embodiments given for illustrative purposes with reference to the appended figures, presented as non-limiting examples, which may serve to complete the understanding of the present invention and the description of its embodiment and, where appropriate, contribute to its definition, in which:

[0019] [Fig. la] [Fig. la], already described, is a schematic representation of an airplane seat equipped with a three-point belt according to the state of the art;

[0020] [Fig.lb] [Fig.lb], already described, is a schematic representation illustrating a displacement of the head of a passenger during a crash;

[0021] [Fig.2] [Fig.2] is a schematic representation of an airplane seat provided with a three-point belt equipped with a pre-tensioning device according to the invention;

[0022] [Fig.3a][Fig.3b][Fig.3c] Figures 3a, 3b and 3c are schematic side views illustrating the operation of a seat belt pre-tensioning device according to the present invention;

[0023] [Fig.4] [Fig.4] is a graphical representation of an evolution over time of a traction in a strap mechanically linked to the pre-tensioning device according to the invention observable during a crash.

[0024] It should be noted that the structural and / or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0025] [Fig. 2] shows an airplane seat 10 comprising a low structure 11 intended to be fixed in particular on rails of an airplane cabin by means of fasteners 12. The seat 10 also comprises a seat 13 carried by the low structure 11 as well as a backrest 15. In the case of a seat 10 of the first class or business class type, the seat 10 may comprise one or more actuators ensuring a pivoting of the backrest 15 around a horizontal axis towards the rear and, if necessary, a movement of the seat 13 towards the front so as to move the seat 10 from a seated position to a bed position in which the backrest 15 defines with the seat 13 a substantially horizontal lying surface so that a passenger 14 can lie down.

[0026] In order to ensure the safety of the passenger 14, the seat 10 may include a belt 16 called a "three-point belt" making it possible to ensure that the passenger 14 is restrained on the seat 10 in the event of an impact by means of three straps having three attachment points on the seat 10. More precisely, the three-point belt 16 includes a lap belt 17 formed by two straps 19 arranged on either side of the passenger 14. The straps 19 each have one end fixed to the lower structure 11 or to the seat 13 by means of a fastener 20. The two straps 19 are connected to each other by means of a belt buckle 21 so as to close the lap belt 17 around the body of the passenger 14.

[0027] The three-point belt 16 further comprises an upper strap 23 intended to hold the upper part of the body of the passenger 14. The upper strap 23 is wound around a locking reel 24 capable of locking the strap 23 when a tensile force greater than an activation threshold SI is applied to the strap 23. The upper strap 23 coming from the reel 24 passes through a passage opening made in the upper part of the backrest 15, in particular at the level of the shoulder of the passenger 14. The upper strap 23 has at its end a fixing interface intended to cooperate with the belt buckle 21.

[0028] The seat 10 is also provided with a pre-tensioning device 27 for the seat belt 16. As can be seen in [Fig.3a], the pre-tensioning device 27 comprises a carriage 28 intended to be mounted movable in translation relative to a structural element, in this case the backrest 15, between an inactive position and an active position. A first elastic member 31 is mounted compressed between the structural element 15 and the carriage 28 when the support 30 is in the locked position.

[0029] A support 30 carrying the reel 24 is mounted on the carriage 28. The support 30 is movable between a locked position in which the support 30 blocks a die translational placement of the carriage 28 relative to the structural element 15 and an unlocked position in which the support 30 allows translational movement of the carriage 28 relative to the structural element 15. For this purpose, the support 30 is mounted to be movable in rotation relative to the carriage 28 around a hinge 33 between the locked position in which a protuberance 34 of the support 30 cooperates with a housing 35 made in the structural element 35 and the unlocked position in which the protuberance 34 of the support 30 is released from the housing 35. In order to cooperate with the housing 35, the protuberance 34 passes through an opening made inside the carriage 28. An axis of the hinge 33 is parallel to an axis of the winder 24.

[0030] An elastic member 37, such as a spring, biases the support 30 into the locked position. The elastic member 37 is mounted inside a housing provided in the carriage 28 and pushes the protuberance 34 towards the housing 35. A calibration of the elastic member 37 defines the activation threshold S1 of the pre-tensioning device 27. The activation threshold S1 is high enough to avoid untimely triggering and low enough to avoid oversizing the elastic member 37. Alternatively, the support 30 may be movable following a translational movement or a combined rotational and translational movement to move from the locked position to the unlocked position, and vice versa.

[0031] A locking finger 38 is biased by an elastic member 42 so as to extend projecting relative to a face of the structural element 15. The locking finger 38 is intended to cooperate with a housing 39 made in the carriage 28 to block the carriage 28 in the active position.

[0032] In order to facilitate the insertion of the locking finger 38 inside the housing 39 when moving the carriage 28, the locking finger 38 has a beveled head 4L

[0033] A stop 46 may be provided in the structural element 15 to limit movement of the carriage 28 in the active position. The distance between one end of the carriage 28 and the stop 46 located opposite this end corresponds to the movement of the carriage 28.

[0034] The pre-tensioning device 27 may comprise a resetting screw 47 cooperating with a threaded opening 48 made in the stop 46.

[0035] The operation of the pre-tensioning device 27 according to the invention is described below, with reference to FIGS. 3a, 3b and 3c.

[0036] As illustrated in [Fig.3a], the carriage 28 is initially in the inactive position.

[0037] As illustrated in [Fig.3b], when the tensile force T applied to the strap 23 exceeds the activation threshold SI, the support 30 pivots around the hinge 33 so as to move from the locked position to the unlocked position in which the protrusion 34 of the support 30 is released from the housing 35 of the backrest 15.

[0038] As illustrated in [Fig.3c], this causes a decompression of the elastic member 31 providing a thrust on the carriage 28 to move it from the inactive position to the active position in which the carriage 28 comes into abutment against the stop 46.

[0039] When the carriage 28 moves towards the active position and passes over the locking finger 38, the beveled head 41 moves initially towards the inside of a cavity of the support 30 due to the compression of the elastic member 42 then in a second time the elastic member 42 decompresses, so that the locking finger 38 cooperates with the housing 39 to hold the carriage 28 in the active position.

[0040] During its movement, the carriage 28 drives the reel 24 via the support 30 so as to apply a pre-tension force Fp on the strap 23.

[0041] [Fig. 4] shows a curve representing the evolution, as a function of time t, of the tensile force T in the strap 23 during a crash. At time t1, the tensile force T applied to the strap 23 exceeds the activation threshold SI defined by the elastic member 37. At time t2, the pre-tensioning device 27 applies a pre-tensioning force Fp to the strap 23 defined by the force of the elastic member 31. The pre-tensioning duration D extends between times t1 and t2. The pre-tensioning force Fp has a value sufficient to compensate for an elongation of the strap 23. The tensile force T follows a bell-shaped curve so as to increase from the start of the crash until time t3 at which the tensile force T reaches its maximum and then gradually decreases to a zero value at the end of the crash.

[0042] In order to reset the pre-tensioning device 27, the operator can pull the locking finger 38 so as to make the head 41 retract inside the housing 39 and allow movement of the carriage 28. The operator can then screw the resetting screw 47 which pushes the carriage 28 in a translational movement towards the inactive position. When the protrusion 34 of the support 30 is opposite the housing 35, the elastic member 37 pushes the support 30 so that the protrusion 34 cooperates with the housing 35 so as to immobilize the carriage 28 in the inactive position. The operator can then release the locking finger 38.

[0043] Alternatively, the structural element is constituted by the seat 13, a piece of furniture located around the seat 10 or even the floor of an aircraft cabin.

[0044] Alternatively, the pre-tensioning device 27 may be devoid of the locking finger 38 and / or the stop 46 which are not essential elements for implementing the invention.

[0045] Alternatively, the strap 23 is connected directly to the support 30 without an intervening winder 24. mediator.

[0046] Alternatively, the strap mechanically linked to the support 30 is a strap other than the upper strap 23 of the three-point belt 16, in particular a strap of the lap belt.

[0047] Of course, the various features, variants and / or embodiments of the present invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0048] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that may be envisaged by those skilled in the art within the scope of the present invention and in particular all combinations of the different operating modes described above, which may be taken separately or in association.

Claims

Claims

1. Pre-tensioning device (27) for a seat belt (16), characterized in that it comprises: - a carriage (28) intended to be mounted movable in translation relative to a structural element (15) between an inactive position and an active position, - a support (30) intended to be mechanically linked to a strap (23) of the seat belt (16), said support (30) mounted on the carriage (28) being movable between a locked position in which the support (30) blocks a translational movement of the carriage (28) relative to the structural element (15) and an unlocked position in which the support (30) allows a translational movement of the carriage (28) relative to the structural element (15), - a first elastic member (31) mounted compressed between the structural element (15) and the carriage (28) when the support (30) is in the locked position,- so that when a tensile force applied to the strap (23) exceeds an activation threshold (SI), the support (30) passes into the unlocked position so as to allow decompression of the first elastic member (31) providing a thrust on the carriage (28) moving from the inactive position to the active position in order to apply a pre-tensioning force to the strap (23).,

2. Pre-tensioning device according to claim 1, characterized in that the support (30) carries a winder (24) around which the strap (23) is wound.

3. Pre-tensioning device according to claim 1 or 2, characterized in that the support (30) is mounted to be movable in rotation relative to the carriage (28) around a hinge (33) between the locked position in which a protuberance (34) of the support (30) cooperates with a housing (35) made in the structural element (15) and the unlocked position in which the protuberance (34) of the support (30) is released from the housing made in the structural element (15).

4. Pre-tensioning device according to claim 3, characterized in that a second elastic member (37) urges the support (30) into the locked position.

5. Pre-tensioning device according to claim 4, characterized in that a calibration of the second elastic member (37) defines the threshold activation (SI) of the pre-tensioning device.

6. Pre-tensioning device according to any one of claims 1 to 5, characterized in that a locking finger (38) is biased by an elastic member (42) so as to extend projecting relative to a face of the structural element (15), said locking finger (38) being intended to cooperate with a housing (39) made in the carriage (28) to block the carriage (28) in the active position.

7. Pre-tensioning device according to any one of claims 1 to 6, characterized in that it comprises a stop (46) provided in the structural element (15) to limit movement of the carriage (28) in the active position.

8. Pre-tensioning device according to claim 7, characterized in that it comprises a resetting screw (47) cooperating with a threaded opening (48) made in the stop (46).

9. Pre-tensioning device according to any one of claims 1 to 8, characterized in that the structural element is a backrest (15) of a seat (10).

10. A seat (10) comprising a safety belt (16) and a pre-tensioning device (27) defined according to any one of the preceding claims.

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