WO2009025594A1

WO2009025594A1 - Safety belt pillar loop height adjustment mechanism

Info

Publication number: WO2009025594A1
Application number: PCT/SE2007/000744
Authority: WO
Inventors: Dan BRÅSE; Erik Hjerpe
Original assignee: Autoliv Development Ab
Priority date: 2007-08-23
Filing date: 2007-08-23
Publication date: 2009-02-26

Abstract

A height-adjustment mechanism for adjusting the height of a safety belt loop (6) on a pillar (4) or other structure in a motor vehicle includes a moveable member (12, 12a) carrying the loop, the member (12,12a) being guided for vertical movement on the pillar (4) by pneumatic means for height adjustment. The mechanism includes means (15,26,47,49) for resisting or preventing alteration of the height of the pillar loop (6) on the pillar (4) in response to forces applied by the safety belt (8) in an accident situation. The pneumatic means may comprise a pneumatic piston and cylinder unit (18) or may comprise a rotary pneumatic motor (41 ) driving a screw (35) directly or via gearing.

Description

Title: Safety Belt Pillar Loop Height Adjustment Mechanism

THIS INVENTION relates to a height adjustment mechanism for a safety belt pillar loop in a motor vehicle.

In a conventional seat belt arrangement for the driver or front-seat passenger of a motor vehicle, the seat belt extends from a lower anchorage point secured to the vehicle frame at the side of the vehicle, passes through a loop in a buckle part and thence through an upper loop secured to the frame of the vehicle adjacent the seat concerned, at approximately the level of the occupant's head or shoulders, and thence passes to a reel with a locking mechanism. In the case of a motor car, the upper loop referred to is secured to the "B"-pillar of the vehicle adjacent the seat in question, i.e. the part of the vehicle frame which extends between the respective front door opening and the respective rear-door opening, or, where there is no rear door, between the front door opening and the adjoining rear side window. Accordingly, such upper loop is generally referred to, and is referred to herein, as a pillar loop.

It is well known to mount such a pillar loop to form an upper anchorage on a height adjustable mechanism on a vehicle B-pillar. It is also well-known to use a motorised height adjuster to adjust the height of the pillar loop for a seat occupant. Such a motorised height adjuster may either be manually operated by an occupant pressing an operating button, or automatically using in-car sensors for sensing the presence of an occupant in the seat concerned and for sensing the height of such occupant.

It is an object of the invention to provide an improved height adjustment mechanism for a vehicle pillar loop for a vehicle seat belt arrangement, which is simple in construction and reliable in operation and which, in particular, does not rely upon electricity to drive the adjustment mechanism.

According to the invention, there is provided a height adjustment mechanism for adjusting the height of a safety belt pillar loop on a pillar in a motor vehicle, the mechanism including a moveable member carrying the pillar loop, said member being guided for vertical movement in guiding means in or on said pillar, characterised by pneumatic means for moving said member in said guiding means to a desired position for height adjustment and means for resisting or preventing alteration of the height of the pillar loop on said pillar in response to forces applied thereto by the safety belt, in an adjusted, locked, state of the adjustment mechanism.

Thus, in embodiments of the present invention, the height adjustment mechanism basically consists of pneumatic driving arrangement for adjusting the height of a safety belt pillar loop on a B-pillar. The pneumatic arrangement may be operated manually by the occupant by pressing an operating button, or automatically by in-car sensors and an ECU. The main advantage of a pneumatic driver is its simplicity, as few parts are required. A further advantage is that no electricity is required to drive the mechanism, which is important, especially if pyrotechnics are involved in seat belt locking or tensioning mechanisms or in related safety devices, such as air-bags.

In one embodiment, the pneumatic means comprises a pneumatic piston and cylinder unit and said means for resisting includes releasable catch means.

In another embodiment, the pneumatic means comprises a rotary pneumatic motor driving, directly, or via reduction gearing a screw or ratchet and pinion arrangement. Embodiments of the invention are described below by way of example with reference to the accompanying drawings in which:-

Figure 1 is a schematic fragmentary side view from within a vehicle showing, in broken lines, a B-pillar of the vehicle and further showing a seat belt pillar loop, with part of a seatbelt passing therethrough and illustrating a pillar loop height adjustment mechanism in accordance with a first embodiment of the invention,

Figure 2 is a fragmentary side view corresponding to Figure 1, but with parts omitted to show a detail, Figure 3 is a fragmentary schematic view looking in the fore and aft direction of the vehicle, partly in vertical section and partly in elevation, of the arrangement of Figures 1 and 2 and with an outer part of the B-pillar omitted,

Figure 4 is a view similar to Figure 3 but showing a variant arrangement, Figure 5 is a view of part of the arrangement of Figure 4, partly in plain and partly in section on the line V-V in Figure 4,

Figure 6 is a view, partly in vertical section, of a detail of Figure 4 to an enlarged scale, and

Figure 7 is a plain view, from above, of the detail of Figure 6.

Referring to Figure 1 , there is indicated at 4 a B-pillar of a motor car, the B-pillar being indicated schematically only in broken lines. Secured to the pillar is a pillar loop 6 for a seat belt shown partially at 8 passing through the loop 6. The seat belt pillar loop 6 and its general location are conventional. Thus the pillar loop 6 is of the conventional triangular form pivotally secured to the vehicle structure by a bolt 10 passing through an aperture provided in the region of the apex of the triangular belt loop 6. In this embodiment, however, the bolt 10 is not fixedly secured to the B-pillar 4 but is secured to a block 12 which is guided for vertical sliding movement in a channel 14 secured by its base to the B-pillar 4, the channel 14 having its longitudinal axis extending generally vertically and parallel with the B-pillar 4. The block 12 is carried at the upper end of a piston rod 16 of a double-acting piston and cylinder unit 18, the cylinder 20 of which is likewise secured to the B-pillar, the longitudinal axis of the piston and cylinder unit being parallel with or coincidental with that of channel 14, and the piston rod extending upwardly from the cylinder. Pneumatic conduits 22 and 24 for compressed air or other gas connect with the upper and lower ends of the cylinder 20. Means, such as valves (not shown) are, of course, provided whereby gas can be discharged from the chamber in the cylinder above the piston when pressurised gas is being supplied to the chamber below the piston to raise the piston and piston rod, and whereby gas can be discharged from the chamber below the piston when the upper chamber is being pressurised by gas to lower the piston and piston rod. The channel 14 has, at intervals along one side-wall thereof, openings or cut-outs 15 for engagement by a spring-biased detent or pawl 26 pivotally mounted in the block 12. The detent or pawl 26 has an upper cam surface which is inclined with respect to the longitudinal axis of the channel 14 so that the detent 26 is cammed inwardly, towards block 12, by the upper edges of successive openings 15 as the block 12 is moved upwards. The spring- biasing of the detent 26 urges the detent 26 outwardly in such a way that it automatically engages in successive openings 15 as the block 12 is moved upwardly relative to the channel 14, i.e. the detent is urged by it spring bias into each opening 15 into which it comes into register. The detent 26 has a lower abutment face 30 extending generally perpendicular to the longitudinal axis of the channel 14 in the projected portion of the detent, for engagement with the lower edge of whichever opening 15 it is engaged in when the block 12 is pulled downwards by forces exerted thereon, via the loop 6, by the belt 8. Accordingly, the detent 26 will effectively resist forcible downward movement of the block 12 in the channel 14 in response to forces acting on the seat belt 8 which would be encountered in a crash situation. The upper end of the piston rod may be connected with the block 12 and the detent 26 in such a way, for example by a lost-motion mechanism, that when the upper end of the piston rod is drawn downwardly during height adjustment, the detent 26 is withdrawn from the openings 15 before it abuts against the lower edge of an opening 15.

A spring 40 may be provided acting between channel 14 and the block 12 so as to pull the block 12 into an uppermost position in the channel 14 whenever the vehicle is vacated and the engine etc turned off. Alternatively a compression spring may be provided acting between cylinder 20 and the block 12, biasing the block 12 upwardly for the same purpose.

It will be appreciated, of course, that in practice the piston and cylinder unit 18, channel 14 and block 12 will be contained within a suitable housing (not shown) secured to the B-pillar 4 and provided with a slot to allow vertical adjusting movement of the bolt 10 carrying the belt loop 6.

It will also be appreciated that, whilst, in the above, reference has been made to the B-pillar of the vehicle, to which the upper belt loops for the front seats of the vehicle will typically be secured, a similar arrangement may be secured to the vehicle frame at a corresponding position adjacent the backs of the rear seats of the vehicle (where such rear seats are present).

In a variant arrangement shown in Figure 4, the upper belt loop 6 is secured by its pivot bolt 10 to a block 12a which is in the form of a screw threaded nut in screw threaded engagement with a screw 35 rotatable in lower and upper brackets 37, 39 secured to the B-pillar or, in a practical embodiment, forming part of an integral bracket 38 secured to the B-pillar, the screw 35 being rotatable, through appropriate gearing, (e.g. reduction gearing), by a rotary pneumatic motor 41 , likewise secured to the B-pillar 4 or to such integral bracket, whereby the screw 35 can be rotated in one direction or the other to raise or lower the block 12a and hence the upper belt loop 6. The direction of rotation of the screw 35 may be changed either by reversing the rotational direction of the motor itself, or by operation of a reversing arrangement in the gearing connecting the motor with the screw 35. The bracket 38 referred to, of course, also incorporates guide means (not shown) co-operating with means on the block 12a restraining rotational movement of the block 12a as the screw 35 rotates whilst permitting vertical movement of the block 12a along the screw 35.

The nature of the screw threaded engagement between the screw 35 and the block 12a and the limited pitch of the screw thread is preferably sufficient to prevent a force applied by the seat belt to the block 12a from moving the block 12a downwards, (or upwards), but for added security, or where the pitch of the screw-thread of screw 35 is made large for rapid adjustment, a locking feature such as described below with reference to Figures 6 and 7 may be utilised. Thus, the screw 35 may be moveable longitudinally to a limited extent in the plain bearings 37 and 39 in which it is rotatable, (the parts of the screw pressing through these bearings being in the form of plain cylindrical journals), and a head portion 45 of the screw may have recesses 47 around its periphery capable of receiving complementary teeth or dogs 49 at the upper end of a cylindrical or annular, for example, element 51 fixed to or integral with the upper bracket 39 and extending upwardly from the latter, the screw being biased upwardly by a compression spring 53 surrounding the upper end of the screw, above the bracket 39 and acting between the screw head 45 and the bracket 39. The spring 53 thus urges the screw 35 into a position in which the head 45 is above the level of the teeth or dogs 49, so that the screw is free to be rotated by the motor 41. However, a downward force applied to the screw 35 from the seat belt in an accident situation will move the head 45 into engagement with element 51 so that even if the screw is caused to rotate slightly, such rotation will be limited to, at most, the pitch between adjacent recesses 47 in the screw head 45, the screw 35 being pulled downwardly as the dogs 49 enter the recesses 47, preventing further rotation of the screw until the downward force on the belt loop 6 is removed.

Means may again be provided to ensure that the upper belt loop 6 is returned to an uppermost position on the screw 39 when the corresponding seat in the vehicle is vacated, and the man in the art will be aware of suitable mechanisms to achieve this end. For example, a torsion spring might be provided at one end of the screw 35, so arranged as to be progressively wound up as the block 12a is lowered from its uppermost position and to rotate the screw 35 in the opposite direction to return the block 12a to its uppermost position once the motor 41 is fully deactivated.

A rotary pneumatic motor might, of course, be arranged to raise or lower the block carrying the belt pillar loop in some other way, for example via a rack and pinion arrangement (not shown) directly or via reduction gearing.

The supply of compressed air or other gas to the piston and cylinder unit 18 or the motor 41 in the embodiments described above may be controlled automatically by operation of a sensor or sensors sensing the presence and height of an occupant of the seat to which the height adjustment mechanism belongs. Alternatively, such supply may be controlled by manual control means operable by the seat occupant, such as a push button or lever, to adjust the pillar loop 6 to a desired height.

Claims

1. A height-adjustment mechanism for adjusting the height of a safety belt pillar loop (6) on a pillar (4) in a motor vehicle, the mechanism including a moveable member (12) carrying the pillar loop, said member (12) being guided for vertical movement in guiding means (14) in or on said pillar, characterised by pneumatic means (18,41) for moving said member in said guiding means (14) to a desired position for height adjustment and means (15,26, 47,49) for resisting or preventing alteration of the height of the pillar loop (6) on said pillar in response to forces applied thereto by the safety belt, in an adjusted, locked, state of the adjustment mechanism.

2. A mechanism according to Claim 1 wherein said pneumatic means comprises a pneumatic piston and cylinder unit (18) and said means for resisting includes releasable catch means (26).

3. A mechanism according to Claim 1 wherein said pneumatic means comprises a rotary pneumatic motor (41) driving directly, or via gearing a screw (35) or rack and pinion arrangement.

4. Apparatus according to Claim 1 which is operated automatically by operation of a sensor or sensor sensing the presence of an occupant of the associated seat and the height of the occupant.

5. Apparatus according to Claim 1 which is operated manually by manual activation of a manual control element.

6. Apparatus according to Claim 5 wherein said control element is a push button or lever.