MECHANICAL PRE-TENSIONING DEVICE FOR A SEAT BELT

Abstract

The invention relates to a pretensioning device (27) for a seat belt comprising: - a carriage (28) intended to be mounted movably 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 translational movement 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), and - a first elastic element (31) mounted in compression between the structural element (15) and the carriage (28) when the support (30) is in the locked position. Figure 3a

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 particularly advantageous application in the field of aeronautics, especially with first-class or business-class aircraft seats.

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

[0003] To ensure the safety of passenger 14, the seat 10 may include a three-point seat belt 16, which restrains passenger 14 in the seat 10 in the event of a collision by means of three straps having three attachment points on the seat 10. More specifically, the three-point seat belt 16 includes a lap belt 17 formed by two straps 19 arranged on either side of passenger 14. Each strap 19 has one end attached 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 passenger 14.

[0004] The three-point seat belt 16 further includes an upper strap 23 for securing the upper body of the passenger 14. The upper strap 23 is wound around a locking retractor 24 capable of locking the strap 23 when a force exceeding a certain threshold is applied to the strap 23. The retractor 24 is fixed to the rear face of the seat back 15. Alternatively, the retractor 24 can be fixed to the lower structure 11 at the level of the aircraft cabin rails. The upper strap 23 from the retractor 24 passes through an opening in the upper part of the seat back 15, specifically at the shoulder of the passenger 14. The upper strap 23 has at its end a fastening interface for engaging with the seat belt buckle. 21.

[0005] As illustrated in [Fig. 1b], during a significant impact, particularly during a crash, the passenger's head 14 moves relative to the seat back 15, which creates 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. This head movement results from several factors, namely: - the rigidity of the seat 10, mainly the lower structure 11 and the backrest 15, - the elongation of the upper strap 23, - elongation of the ventral girdle 17, - the reel locking time is 24, and - the tension of the upper strap 23 inside the winder 24.

[0006] The invention aims to effectively remedy the aforementioned drawbacks by proposing a pre-tensioning device for a seat belt, comprising: - a trolley designed to be mounted to move in translation relative to a structural element between an inactive position and an active position - a support intended to be mechanically linked to a seat belt strap, said support mounted on the trolley being movable between a locked position in which the support blocks translational movement of the trolley relative to the structural element and an unlocked position in which the support allows translational movement of the trolley relative to the structural element, - a first elastic element mounted in compression 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 to allow decompression of the first elastic element ensuring a push on the carriage moving from the inactive position to the active position in order to apply a pretension force on the strap.

[0007] The invention thus makes it possible to reduce or even eliminate the effects of the aforementioned factors, namely the elongation of the upper strap, the elongation of the lap belt, the locking time of the retractor, and the tension of the upper strap inside the retractor (with the exception of the rigidity of the seat), in order to significantly limit the displacement of a passenger's head during a crash. The invention also offers 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 rotate movably relative to the carriage around a hinge between the locked position in which a protrusion of the support cooperates with a housing made in the structural element and the unlocked position in which the protrusion of the support is free from the housing made in the structural element.

[0010] According to one embodiment of the invention, a second elastic element stresses the support in the locked position.

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

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

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

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

[0015] According to one embodiment of the invention, said pre-tensioning device comprises a reset 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-tension device as previously defined.

[0018] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures, presented by way of non-limiting examples, which may serve to complete the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

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

[0020] [Fig.lb] The [Fig.lb], already described, is a schematic representation illustrating a movement of a passenger's head during a crash;

[0021] [Fig.2] The [Fig.2] is a schematic representation of an aircraft seat equipped with a three-point belt fitted 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 pretensioning device according to the present invention;

[0023] [Fig.4] The [Fig.4] is a graphic representation of an evolution as a function of 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 reference numerals. Thus, unless otherwise specified, such elements have identical structural, dimensional and material properties.

[0025] Figure 2 shows an aircraft seat 10 comprising a lower structure 11 intended to be fixed in particular to rails of an aircraft cabin by means of fasteners 12. The seat 10 also comprises a seat 13 supported by the lower structure 11 and a backrest 15. In the case of a first-class or business-class seat 10, the seat 10 may include one or more actuators ensuring a pivoting of the backrest 15 around a horizontal axis towards the rear and, where applicable, a movement of the seat 13 towards the front so as to move the seat 10 from a sitting position to a bed position in which the backrest 15 defines with the seat 13 a substantially horizontal sleeping surface so that a passenger 14 can lie down.

[0026] To ensure the safety of passenger 14, the seat 10 may include a three-point seat belt 16, which restrains passenger 14 in the seat 10 in the event of a collision by means of three straps having three attachment points on the seat 10. More specifically, the three-point seat belt 16 includes a lap belt 17 formed by two straps 19 arranged on either side of passenger 14. Each strap 19 has one end attached 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 passenger 14.

[0027] The three-point seat belt 16 further comprises an upper strap 23 intended to restrain the upper body of the passenger 14. The upper strap 23 is wound around a locking retractor 24 capable of locking the strap 23 when a tensile force exceeding an activation threshold SI is applied to the strap 23. The upper strap 23 from the retractor 24 passes through an opening in the upper part of the seat back 15, specifically at the shoulder of the passenger 14. The upper strap 23 has at its end a fastening interface intended to cooperate with the seat belt buckle 21.

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

[0029] A support 30 carrying the winder 24 is mounted on the carriage 28. The support 30 is movable between a locked position in which the support 30 blocks a de The support 30 is positioned in translation relative to the structural element 15 and in 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 rotate relative to the carriage 28 around a hinge 33 between the locked position, in which a protrusion 34 of the support 30 cooperates with a recess 35 in the structural element 35, and the unlocked position, in which the protrusion 34 of the support 30 is disengaged from the recess 35. In order to cooperate with the recess 35, the protrusion 34 passes through an opening in the carriage 28. An axis of the hinge 33 is parallel to an axis of the winder 24.

[0030] An elastic element 37, such as a spring, forces the support 30 into the locked position. The elastic element 37 is mounted inside a housing provided in the carriage 28 and pushes the protrusion 34 towards the housing 35. A calibration of the elastic element 37 defines the activation threshold SI of the pre-tensioning device 27. The activation threshold S1 is high enough to prevent unwanted triggering and low enough to avoid oversizing the elastic element 37. Alternatively, the support 30 can be movable by 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 induced by an elastic member 42 so as to extend in projection 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 lock the carriage 28 in the active position.

[0032] To facilitate the insertion of the locking finger 38 into the housing 39 when moving the carriage 28, the locking finger 38 has a beveled head 4L

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

[0034] The pre-tensioning device 27 may include a reset 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 Figures 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 clear of the housing 35 of the backrest 15.

[0038] As illustrated in [Fig.3c], this generates a decompression of the elastic member 31 ensuring a push on the carriage 28 to move it from the inactive position to the active position in which the carriage 28 comes to rest 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 firstly towards the inside of a cavity in the support 30 due to the compression of the elastic element 42 and then in a second step the elastic element 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 trolley 28 drives the winder 24 via the support 30 so as to apply a pre-tension force Fp on the strap 23.

[0041] Figure 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 element 37. At time t2, the pretensioning device 27 applies a pretension force Fp to the strap 23 defined by the force of the elastic element 31. The pretension duration D extends between times t1 and t2. The pretension force Fp has a sufficient value to compensate for the elongation of the strap 23. The tensile force T follows a bell-shaped curve, increasing from the beginning of the crash until time t3, at which point the tensile force T reaches its maximum, and then gradually decreasing to zero at the end of the crash.

[0042] To reset the pre-tensioning device 27, the operator can pull the locking pin 38 so as to retract the head 41 into the housing 39 and allow the carriage 28 to move. The operator can then tighten the reset screw 47, which pushes the carriage 28 in a translational movement to the inactive position. When the protrusion 34 of the support 30 is aligned with the housing 35, the elastic element 37 pushes the support 30 so that the protrusion 34 engages with the housing 35, thus immobilizing the carriage 28 in the inactive position. The operator can then release the locking pin 38.

[0043] Alternatively, the structural element consists of 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 the implementation of the invention.

[0045] Alternatively, the strap 23 is connected directly to the support 30 without an inter- winder 24 median.

[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 different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as 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 a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Demands

1. A pretensioning device (27) for a seat belt (16), characterized in that it comprises: - a carriage (28) intended to be mounted movably 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 in compression 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) moves to the unlocked position to allow decompression of the first elastic element (31) which provides a push on the carriage (28) moving from the inactive position to the active position in order to apply a pre-tension 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 movable in rotation relative to the carriage (28) about a hinge (33) between the locked position in which a protrusion (34) of the support (30) cooperates with a housing (35) made in the structural element (15) and the unlocked position in which the protrusion (34) of the support (30) is clear of the housing made in the structural element (15).

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

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

6. Pre-tensioning device according to any one of claims 1 to 5, characterized in that a locking finger (38) is induced by an elastic member (42) so as to extend in projection 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 lock the carriage (28) in 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 a movement of the carriage (28) in the active position.

8. Pre-tensioning device according to claim 7, characterized in that it comprises a reset 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 seat back (15) (10).

10. Seat (10) comprising a safety belt (16) and a pretensioning device (27) as defined in any one of the preceding claims.

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