GB2505771A

GB2505771A - Load-limiter for seat belt buckle

Info

Publication number: GB2505771A
Application number: GB201313447A
Authority: GB
Inventors: H N Naveen Kumar; Gopal Krishnan Chinnaswamy; Kalyan Cheruvu
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2013-07-29
Filing date: 2013-07-29
Publication date: 2014-03-12
Also published as: GB201313447D0

Abstract

A load limiting device 1 for a buckle 3 of a seat belt 2 of a motor vehicle comprises a connecting rod 9 connected to buckle 3 and having a head 8 guided in a block 10 having a track 12. Head 8 is movable along block 10 upon application of a drag force 15 to buckle 3, developing a direction-dependent variable retention force 16. Track 12 has at least one area 17 in which the retention force 16 is substantially cancelled upon movement of head 8 along block 10. Track 12 preferably has an undulating contour on the upper and lower sides of block 10, and may be deformable by head 8 sliding along track 12. Gaps (c, d, e, Figure 3) between areas 17 where the retention force is substantially cancelled may be variable to adjust the deceleration of head 8.

Description

Daimler AG Load limiting device for a seat belt of a motor vehicle The invention relates to a load limiting device for a seat belt of a motor vehicle according to the preamble of claim 1.

Such a load limiting device can for example already be taken as known from US 7784831 B2. The load limiting device there has two plates adjustable to each other in their mutual inclination by means of respective electric motors, wherein by means of these plates, a spherically formed retention element is clamped between these plates in case of an accident. Therein, the spherical retention element is connected to a buckle assembly of the load limiting device in force transmitting manner. In case of an accident of the vehicle, the fastened person seated in the vehicle is retained by the load limiting device, wherein a drag force is exerted on the retention device by means of the buckle assembly. As a result, the spherically formed retention element is pulled along between the two plates and exerts a force deforming these plates. The plates can be adjusted in their inclination to each other, wherefore the load limiting device is variably adjustable with respect to its retention force. Thus, for example, by means of decrease of the distance of the two plates, an enhanced retention effect of the load limiting device can be achieved, since the spherical retention element does higher work depending on the way traveled between these two plates due to a higher contact force of the retention element on the plates. As a result, the person seated in the vehicle is decelerated on a particularly short way and thereby in particularly strong manner in case of an accident.

However, if the two plates are further spaced from each other, thus, the retention element can travel a larger way with the same done work in case of an accident, whereby the person seated in the vehicle is decelerated in less strong manner, but in return over a longer way due to the lower contact force.

It is the object of the present invention to provide a load limiting device of the initially mentioned kind, by means of which the person seated in the vehicle is secured in case of an accident with application of a retention force dosed in particularly occupant sparing manner.

According to the invention, this object is solved by a load limiting device having the features of claim 1. Advantageous configurations with convenient developments of the invention are specified in the remaining claims.

In order to provide a load limiting device of the initially mentioned kind, in which the person seated in the vehicle is retained in particularly sparing manner in case of an accident, it is provided according to the invention that the leading outline of the load limiting block has at least one area, in which the retention force is at least substantially cancelled upon movement of the connecting rod head along the load limiting block. In case of severe traffic accidents, injuries of the cervical spine of the persons seated in the vehicle and retained by means of a load limiting device upon impact often occur. The cause of such cervical spine injuries is usually vigorous relative movements between head and torso by abrupt torso accelerations or decelerations. Thus, the torso of the occupants is decelerated by the cooperation of belt pretensioner, seat belt and the load limiting device, but the head of the occupants cannot be prevented from being subject to extreme acceleration and deceleration within the scope of a whiplash relative movement related to the torso. However, if the retention force is cancelled at least in one area upon movement of the connecting rod head of the load limiting device along the load limiting block, thus, a movement clearance for the torso in case of an accident is provided, whereby the relative movement between head and torso is less severely pronounced. By the cancellation of this retention force at least in certain areas, thus, injury of the cervical spine is particularly effectively prevented.

Further advantages, features and details of the invention are apparent from the following description of a preferred embodiment as well as based on the drawings.

They show in: Fig. 1 a schematic isometric view of a load limiting device according to the invention, wherein a connecting rod head of a connecting rod device is movable guided in a load limiting block; Fig. 2 a schematic section view of the load limiting device according to a section line A-A shown in Fig. 1; and in Fig. 3 a schematic plan view of the load limiting device! wherein a deceleration of the connecting rod head upon movement thereof in the load limiting block is adjustable by means of different lengths of respective length ranges.

Fig. 1 shows a schematic isometric view of a load limiting device 1 according to the invention. From the synopsis of Fig. 1 and the schematic section view of the load limiting device 1 shown in Fig. 2 according to a section line A-A shown in Fig. 1, it is recognizable that a seat belt 2 is coupled to a connecting rod head 8 of the load limiting device 1 for transmitting a drag force 15 corresponding to a drag force application. In order to now transmit the drag force 15, the seat belt 2 is fixed to a buckle assembly 3.

This is a fixation detachable by the vehicle occupant by means of operation of an operating element not illustrated here. This operating element can for example be formed as a press button disposed on the buckle assembly 3. The buckle assembly 3 is coupled to a cable 4 in force transmitting manner, wherein this cable 4 is deflected by means of a revolute joint 5. The cable 4 can be a cable formed of metal or a wire on the one hand, but the formation of the cable 4 of plastic or of textile-like fabric is also possible. By intervention of the revolute joint 5, the cable 4 is now deflected and finally enters a cable guide 6. As soon as the drag force 15 occurs for example in case of an accident, thus, the cable 4 is pulled along a pull direction 11 with intervention of the cable guide 6. The cable 4 is now coupled to a connecting rod device 9 in force transmitting manner, wherein this connecting rod device 9 includes a connecting rod 7, which is coupled to the cable 4 in force transmitting manner. Furthermore, the connecting rod device 9 includes the connecting rod head 8, which is coupled to the connecting rod 7 in force transmitting manner. However, alternatively, the connecting rod 7 could also be omitted and thus the cable 4 could be directly coupled to the connecting rod head 8 in force transmitting manner. Presently, the connecting rod head 8 of the connecting rod device 9 is now received by a load limiting block 10, wherein this load limiting block 10 has a leading outline 12 with a substantially undulated formed lower contour 19 and a substantially undulated formed upper contour 18. In other words, the leading outline 12 is thus formed of the upper contour 18 and the lower contour 19. In case of application of the drag force 15 to the cable 4, the connecting rod device 9 is moved along the pull direction 11 due to its fixation to the cable 4. Since the leading outline 12 of the load limiting block 10 has at least one area 17, in which a retention force 16 is at least substantially cancelled upon movement of the connecting rod head 8 of the connecting rod device 9 along the load limiting block 10. the retention force 16 opposing the drag force 15 is a force pulsing depending on movement. This is founded in that the connecting rod head 8 slides substantially without contact along the upper contour 18 and the lower contour 19 upon movement thereof through the respective areas 17 and the contact force between the upper area 18 and the lower area 19 and the connecting rod head 8 in the respective areas 17 has at least a smaller magnitude than in other narrower areas 20 of the leading outline 12 different from the areas 17, respectively.

Namely, if the connecting rod head 8 is moved through the areas 20 of the leading outline 12, thus, the connecting rod head 8 is particularly severely pressed to the upper contour 18 and the lower contour 19. As a result, the retention force 16 is particularly great upon movement of the connecting rod head 8 through the areas 20. Since the leading outline 12 presently has the respective areas 17 and the areas 20 each in alternating manner in pull direction 11, the retention force 16 is either particularly great or particularly small according to where the connecting rod head 8 is currently located, thus whether the connecting rod head 8 is currently in one of the respective areas 17 or in one of the respective areas 20. If the connecting rod head 8 is currently in one of the respective areas 17 upon movement thereof along the leading outline 12 of the load limiting block 10, thus, the retention force 16 is particularly small. However, it the connecting rod head 8 is currently in one of the respective areas 20, thus, the retention force 16 is particularly great. Thus, the retention force 16 is a pulsing force, the magnitude of which intermittently varies and depends on the respective position of the connecting rod head 8 relative to the load limiting block 10 upon movement thereof along the leading outline 12. In other words, since the retention force 16 thus occurs in pulsing manner, the buckle assembly 3 and thereby also the seat belt 2 are alternately accelerated and decelerated upon movement of the connecting rod head 8 along the leading outline 12. The leading outline 12 of the load limiting block 10 is furthermore deformable depending on the application of the drag force 15. The connecting rod head 8 does respective deformation work on the upper contour 18 and/or the lower contour 19 upon movement thereof along the leading outline 12. This deformation work primarily relates to the respective areas 20, but the respective areas 17 are also deformable, albeit not to such an extent as the areas 20. However, alternatively, both the leading outline 12 of the load limiting block 10 and the connecting rod head 8 can also be formed of a material deformable by deformation work. Alternatively, either the connecting rod head 8 or the load limiting block 10 can also be formed of a high-strength material, which is particularly resistant with respect to deformation work.

As is apparent from the synopsis of Fig. 1 as well as a schematic plan view of the load limiting device 1 in Fig. 3, the respective areas 20 have respective latitude ranges 13 as well as respective length ranges 14. Therein, in Fig. 1, the respective latitude ranges 13 have a respective latitude a, whereas the respective length ranges 14 have a length b. In other words, the respective areas 20 shown in Fig. 1 have the respectively identical latitude ranges 13 as well as the respectively identical length ranges 14. By means of length variation of the respective length ranges 14 and/or a latitude variation of the respective latitude ranges 1301 the leading outline 12, a deceleration of the connecting rod head 8 constant on average upon movement thereof in the load limiting block 10 is adjustable on the one hand, or a progressive deceleration of the connecting rod head 8 or degressive deceleration of the connecting rod head 8.

Fig. 3 contains essential components already described in the context of Fig. 1 and Fig. 2, respectively, wherefore only the differences are dealt with in the following. Thus, in Fig. 3, it is shown how by means of respectively different respective lengths c, d, e of the respective length ranges 14 of the respective areas 20, a deceleration of the connecting rod head 8 varying upon movement of the connecting rod head 8 in the load limiting block 10 is adjustable. For example, if the length c has the largest magnitude of these lengths c, d, e and the length e has the smallest magnitude, thus, a deceleration of the connecting rod head 8 progressive on average is achieved upon movement thereof along the leading outline 12. The occupants retained by the load limiting device 1 in case of an accident are therefore first particularly severely decelerated during the movement of the connecting rod head 8 along the length range 14 with the length c, wherein the retention force 16 accordingly opposes the drag force 15 along a particularly long way.

Upon movement of the connecting rod head 8 along the length range 14 with the length e, the occupant is particularly little decelerated. Accordingly, the retention force 15 opposes the drag force 15 along a particularly short way.

Claims

Daimler AG Claims 1. Load limiting device (1) for a seat belt (2) of a motor vehicle, including a connecting rod device (9) connected to a buckle assembly (3), including a connecting rod head (8), which is guided in a load limiting block (10) having a leading outline (12) and is movable along the load limiting block (10) upon application of a drag force (15)to the buckle assembly (3) with development of a way-dependent variable retention force (16), characterized in that the leading outline (12) of the load limiting block (10) has at least one area (17), in which the letention foice (16) is at least substantially canceled upon movement of the connecting rod head (8) along the load limiting block (10).
2. Load limiting device (1) according to claim 1, characterized in that the leading outline (12) has at least one substantially undulated formed upper contour (18).
3. Load limiting device (1) according to claim 1 or 2, characterized in that the leading outline (12) has at least one substantially undulated formed lower contour (19).
4. Load limiting device (1) according to any one of claims ito 3, characterized in that the leading outline (12) of the load limiting block (10) is defoimable depending on the application of the drag force (15).
5. Load limiting device (1) according to any one of claims ito 4, characterized in that by means of a length variation of respective length ranges (14) and/or a latitude variation of respective latitude ranges (13) of the leading outline (12), a deceleration of the connecting rod head (8) constant on average upon movement thereof in the load limiting block (10) is adjustable.
6. Load limiting device (1) according to any one of claims ito 4, characterized in that by means of a length variation of respective length ranges (14) and/or a latitude variation of respective latitude ranges (13) of the leading outline (12), a deceleration of the connecting rod head (8) progressive on average upon movement thereof in the load limiting block (10) is adjustable.
7. Load limiting device (1) according to any one of claims ito 4, characterized in that by means of a length variation of respective length ranges (14) and/or a latitude variation of respective latitude ranges (13) of the leading outline (12), a deceleration of the connecting rod head (8) degressive on average upon movement thereof in the load limiting block (10) is adjustable.