GB2514913A - Restraint system for a vehicle - Google Patents

Abstract

A vehicle seat restraint system comprises a seatbelt spool 12 with a toothed pinion 20 arranged to tighten a seatbelt 14 when pretensioner device 18 is triggered. The pretensioner device 18 has pretensioner balls 22 which travel within a guide element tube 24 to engage with the toothed pinion 20. Protrusions 36a-c on the guide surface allow the balls 22 to pass toward the pinion 20 but restrict movement in the balls 22 away from the pinion 20 temporarily, at least. The protrusions 36a-c can be in the form of fins arranged diagonally to chock the balls when the seatbelt is extended; if sufficient force is applied the fins 36a-c will deform to allow the balls 22 to pass back past and so limit the load on the passenger. A pyrotechnic actuator 30 triggers the movement of the balls 22 along the guide tube 24 toward the toothed pinion 20.

Description

Restraint System for a Vehicle The invention relates to a restraint system according to the preamble of patent claim 1.

Such a restraint system for a vehicle is known from US 2010/0084906 Al. The restraint system comprises a spool for receiving at least a portion of a seat belt. This means at least a portion of the seat belt can be wound onto the spool and unwound from the spool.

The spool is rotatable about a rotation axis due to unwinding the seat belt from the spool.

Furthermore, the restraint system comprises a pretensioner device having a pinion rotatable about the rotation axis and capable of driving the spool about the rotation axis.

This means the pinion is connected or connectable to the spool so that the spool can be rotated about the rotation axis by rotating the pinion about the rotation axis.

The pretensioner device further comprises pretensioner balls configured to engage the pinion. Moreover, the pretensioner device comprises at least one guide element having a guide surface configured to guide the pretensioner balls along a path in such a way that the pretensioner balls engage the pinion thereby driving the pinion and the spool about the rotation axis. In other words, the spool can be driven about the rotation axis via the pinion by moving the pretensioner balls along the path in such a way that the pretensioner balls engage the pinion and, thus, rotate the pinion about the rotation axis. For example, the pretensioner balls are driven along the path by means of at least one pyrotechnic actuator.

It is an object of the present invention to provide a restraint system of the aforementioned kind, by means of which loads exerted on a seat passenger by the seat belt can be limited particularly advantageously.

This object is solved by a restraint system having the features of patent claim 1.

Advantageous embodiments with expedient and non-trivial developments of the invention are indicated in the other patent claims.

In order to provide a restraint system of the kind indicated in the preamble of patent claim 1, by means of which restraint system the load exerted on a seat passenger by a seat belt in the case of an accident can be limited particularly advantageously, according to the present invention, the pretensioner device comprises at least one load limiting element protruding from the guide surface into the path in such a way that the load limiting element allows the movement of the pretensioner balls along the path towards the pinion but restricts the movement of the pretensioner balls along the path away from the pinion at least temporarily. This means, during an accident, the pretensioner balls are restricted or blocked at least temporarily in such a way that the pretensioner balls cannot move back along the path away from the pinion. Thus, the movement of the spool can be blocked or at least restricted so that the load exerted on a seat passenger by the seat belt during an accident can be limited.

The load limiting effect provided by the pretensioner device works for both directions of rotation about the rotation axis. This means the load can be limited if, for example, the seat belt is unwound from the spool thereby driving the spool in a first direction of rotation about the rotation axis. Moreover, the load can be limited if the seat belt is wound onto the spool, wherein the spool rotates in a second direction of rotation about the rotation axis, the second direction of rotation being opposite of the first direction of rotation. Moreover, the load exerted on a seat passenger by the seat belt during a crash can be limited by means of the restraint system according to the present invention without using a torsion bar. In other words, there is no need for a torsion bar for limiting the load acting upon the seat passenger. By limiting or lowering the forces exerted by the seat belt on a seat passenger during a crash, injuries of the seat passenger or an occupant can be kept particularly low.

Further advantages, features, and details of the invention derive from the following description of a preferred embodiment as well as from the drawing. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respective indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

The drawing shows in: Fig. 1 a schematic sectional view of a restraint system for a vehicle, the restraint system comprising load limiting elements protruding from a guide surface configured to guide pretensioner balls; Fig. 2 a further schematic and sectional view of the restraint system; Fig. 3 part of a schematic sectional view of the restraint system according to Fig. 2; Fig. 4 a further schematic sectional view of the restraint system; Fig. 5 a further schematic sectional view of the restraint system; and Fig. 6 part of a schematic sectional view of the restraint system according to Fig. 5.

In the figures the same elements or elements having the same function are indicated with the same reference sign.

Fig. 1 shows a restraint system 10 for a vehicle. The restraint system 10 comprises a spool 12 for receiving at least a portion of a seat belt 14. The seat belt 14 is configured to restrain a seat passenger in the case of an accident, for example, a frontal impact. The spool 12 is rotatable about a rotation axis 16. With respect to the image pane of Fig. 1, at least a portion of the seat belt 14 can be wound onto the spool 12 by rotating the spool 12 about the rotation axis 16 in a clockwise direction. By unwinding the portion from the spool 12, the spool 12 can be rotated about the rotation axis 16 a counter-clockwise direction.

The restraint system 10 further comprises a pretensioner device 18 having a pinion 20.

The pinion 20 is rotatable about the rotation axis 16 and capable of driving the spool 12 about the rotation axis 16. In the present case, the pinion 20 is connected to the spool 12 in a rotationally fixed manner. This means the spool 12 can be rotated about the rotation axis 16 via the pinion 20 in a first direction of rotation and a second direction of rotation being opposite of the first direction of rotation.

The pretensioner device 18 comprises pretensioner balls 22 configured to engage the pinion 20. For example, the pretensioner balls 22 are spheres. Furthermore, the pretensioner device 18 comprises a guide element in the form of a duct element 24 having a guide surface 26 configured to guide the pretensioner balls 22 along a path through a duct 28 bounded by the guide surface 26. For example, the duct element 24 is designed as a tube. The guide surface 26 is configured to guide the pretensioner balls 22 in such a way that the pretensioner balls 22 engage the pinion 20 thereby driving the pinion 20 and the spool 12 about the rotation axis 16 clockwise thereby winding at least a portion of the seat belt 14 onto the spool 12. Thereby, any slack between the seat belt 14 and the seat passenger which is also referred to as "occupant" can be removed.

The pretensioner device 18 further comprises an actuator which is designed as a pyrotechnic actuator 30. The pyrotechnic actuator 30 comprises a spark ignition device 32 and a propellant 34, the spark ignition device 32 being capable of triggering the propellant 34.

The pretensioner device 18 also comprises load limiting elements in the form of load limiting fins 36a-c. The load limiting fins 36a-c protrude from the guide surface 26 into the path and the duct 28 in such a way that the load limiting fins 36a-c allow the movement of the pretensioner balls 22 along the path through the duct 28 towards the pinion 20 but restrict the movement of the pretensioner balls 22 along the path away from the pinion 20 at least temporarily during an accident. As can be seen in Fig. 1, the load limiting fins 36a-c protrude diagonally in relation to the direction of movement of the pretensioner balls 22 from the guide surface 26 towards the pinion 20. If an accident, for example, a frontal impact is detected by at least one sensor, the propellant 34 is triggered by means of the spark ignition device 32. Thereby, the pretensioner balls 22 are propelled by the triggered propellant 34 along the path towards the pinion 20 so that at least some of the pretensioner balls 22 engage the pinion 20.

As can be seen from Fig. 2, the pinion 20 and, thus, the spool 12 are rotated about the rotation axis 16 clockwise by the propelled pretensioner balls 22 so that at least a portion of the seat belt 14 is wound onto the spool 12. Thereby, in early stages of a crash any slack between the seat belt 14 and the occupant can be removed.

By triggering the propellant 34, a gas and, thus, gas pressure is generated in the duct element 24. Said gas expands thereby pushing the pretensioner balls 22 along the path towards the pinion 20 so that the pinions 20 and, thus, the spooi 12 are rotated by the rotation axis 16.

As can be seen from Fig. 3, the load limiting fins 36a-c bend as shown due to forces exerted on the load limiting fins 36a-c by the pretensioner balls 22 when the pretensioner balls 22 are propelled by the triggered propellant 34 along the path towards the pinion 20.

For example, the pretensioner balls 22 are made of steel. Since the load limiting fins 36a-c bend towards the guide surface 26, the pretensioner balls 22 can move past the load limiting fins 36a-c towards the pinion 20. In other words, the pretensioner balls 22 can slip between the load limiting fins 36a-c and the guide surface 26 towards the pinion 20.

Hence, the pretensioner balls 22 can engage the pinion 20 as shown in Fig. 4. The pretensioner balls 22 engaging the pinion 20 rotate the spool 12 to wind the seat belt 14 or at least a portion of the seat belt 14 up to the spool 12.

For example, said gas pressure can be decreased by guiding the gas out of the duct 28 via, for example, at least one exhaust hole. The pretensioner balls 22 can be moved through the duct 28. The load limiting fins 38a-c are configured as flexible ribs which allow the pretensioner balls 22 to move past the load limiting fins 36a-c towards the pinion 20.

In the further process of the frontal impact, the occupant starts to move forward. Thus, a load is exerted on the seat belt 14 by the occupant, the load being transferred from the seat belt 1410 the spool 12. Said load is illustrated in Fig. S by a directional arrow 38.

Thereby, the spool 12 and, thus, the pinion 20 are moved counter clockwise about the rotation axis 16 by means of the seat belt 14. Hence, the pretensioner balls 22 are moved along the path away from the pinion 20. However, at least some of the pretensioner balls 22 come into contact with the load limiting fins 36a-c so that the movement of the pretensioner balls 22 along the path back away from the pinion 20 is blocked or restricted at least temporarily.

The load limiting fins 36a-c are configured to allow the movement of the pretensioner balls 22 along the path away from the pinion 20 due to deformations of the respective load limiting fins 36a-c, the deformations being caused by a load exerted on the load limiting element by the pretensioner balls 22 moving away from the pinion 20, the load exceeding a predeterminable threshold. In other words, if the load exerted on the pinion by the seat belt 14 and, thus, if the load exerted on the load limiting fins 36a-c by the pretensioner balls 22 exceeds a predeterminable threshold, the load limiting fins 36a-c are deformed in such a way that the pretensioner balls 22 can be moved back along the path away from the pinion 20 and past the load limiting tins 36a-c. For example, the load limiting tins 36a-c break if the load exceeds the predeterminable threshold. This means the load limiting tins 36a-c can withstand a predeterminable load betore deforming and breaking which results in a resistance blocking or limiting the unwinding trom the seat belt 14 from the spool 12 and, thus, the load acting upon the occupant via the seat belt 14.

Limiting the load helps keep the injuries of the occupant particularly low.

By means ot the pretensioner device 18, the loads exerted on the occupant by the seat belt 14 can be limited particularly advantageously without using a torsion bar. Thus, the number of parts, the weight and the cost ot the restraint system 10 can be kept particularly low.

List of reference signs restraint system 12 spool 14 seat belt 16 rotation axis 18 pretensioner device pinion 22 pretensioner balls 24 duct element 26 guide surface 28 duct pyrotechnic actuator 32 spark ignition device 34 propellant 36a-c load limiting fin 36 directional arrow

Claims (4)

1. Claims A restraint system (10) for a vehicle, the restraint system (10) comprising: -a spool (1 2) for receiving atleasta portion of a seat belt (14), the spool (12) being rotatable about a rotation axis (16) due to unwinding the seat belt (14) from the spool (12); and -a pretensioner device (18) having: o a pinion (20) rotatable about the rotation axis (16) and capable of driving the spool (12) about the rotation axis (16); o pretensioner balls (22) configured to engage the pinion (20); o at least one guide element (24) having a guide surface (26) configured to guide the pretensioner balls (22) along a path (28) in such a way that the pretensioner balls (22) engage the pinion (20) thereby driving the pinion (20) and the spool (12) about the rotation axis (16); characterised in that the pretensioner device (18) comprises at least one load limiting element (36a) protruding from the guide surface (26) into the path (28) in such a way that the load limiting element (36a) allows the movement of the pretensioner balls (22) along the path (28) towards the pinion (20) but restricts the movement of the pretensioner balls (22) along the path (28) away from the pinion (20) at least temporarily.
2. 2. The restraint system (10) according to claim 1.characterised in that the load limiting element (36a) protrudes from the guide surface (26) towards the pinion (20) diagonally in relation to the direction of movement of the pretensioner balls (22).
3. 3. The restraint system (10) according to any one of claims 1 or 2, characterised in that the load limiting element (36a) is configured to allow the movement of the pretensioner balls (22) along the path (28) away from the pinion (20) due to a deformation of the load limiting element (36a), the deformation being caused by a load exerted on the load limiting element (36a) by the pretensioner balls (22). the load exceeding a predeterminable threshold.
4. 4. The restraint system (10) according to any one of the preceding claims, characterised in that the pretensioner device (18) comprises at least one second load limiting element (36b) being arranged at a distance from the first load limiting element (36a) with respect to the direction of movement of the pretensioner balls (22) along the path (28).