Vehicle seat assembly

A vehicle seat assembly comprises a vehicle seat comprising a rigid frame, one or more resilient portions and a covering material, wherein an openable deployment seam is provided at a portion of the covering material, and wherein the vehicle seat defines a recess. An airbag module is provided within the recess and comprises a housing, an airbag and an inflator system. Also provided is gripping means which is movable between a first position and a second position in which the portion of the covering material is restrained to assist deployment of the airbag through the deployment seam.

TECHNICAL FIELD

The present invention relates to a vehicle seat assembly including an airbag. In particular, but not exclusively, the invention relates to a vehicle seat assembly including a side airbag module having means for improved deployment of the airbag.

BACKGROUND OF THE INVENTION

It is known to mount an inflatable side airbag module to a vehicle seat. In the event of an impact, the airbag can be rapidly deployed to a position between the occupant and the adjacent vehicle door or body structure. The side airbag functions to dampen and distribute the impact load to reduce injuries. It is desirable that the airbag is fully deployed within around 20 milliseconds from impact.

The vehicle seat comprises a rigid frame to which foam pads are attached. The seat is covered by a layer of material made of vinyl, cloth or leather. The airbag module is connected to the seat frame and comprises a housing, the airbag and an inflator system.

Typically, the deploying airbag is channelled so that it deploys through a tearable seam in the covering material. However, the elasticity of both the covering material and the foam padding can reduce the rate of airbag deployment. Valuable deployment time is lost as the expanding airbag compresses the foam and stretches the covering material. This may also cause the airbag to deploy to a different location from the desired location.

It is known to use a force concentrator that partially surrounds the folded airbag and directs the force of the inflating airbag towards the deployment seam of the seat. Such a system is disclosed in US 2006/0113766. The force concentrator comprises one or more rigid panels. However, the size and position of the panels complicates assembly and locating the device within the seat.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a vehicle seat assembly comprising:

a vehicle seat comprising a rigid frame, one or more resilient portions and a covering material, wherein an openable deployment seam is provided at a portion of the covering material, and wherein the vehicle seat defines a recess;

an airbag module provided within the recess and comprising a housing, an airbag and an inflator system; and

gripping means which is movable between a first position and a second position in which the portion of the covering material is restrained to assist deployment of the airbag through the deployment seam.

The gripping means may be movable from the first position to the second position by deployment of the airbag.

The housing may be adapted to expand during deployment of the airbag. A portion of the housing may be adapted to move towards the covering material during deployment of the airbag.

An opening, weakening feature, abutting edges or the like may be provided at the housing such that two portions of the housing move apart during deployment of the airbag. The housing may include a hinge member to assist the two portions moving apart. The hinge member may be provided at an opposite end of the housing to the opening, weakening feature, abutting edges or the like.

The airbag module may be adapted such that the two portions of the housing moving apart during deployment of the airbag causes the gripping means to move from the first position to the second position.

The gripping means may be provided at, or coupled to, an exterior surface of the housing. The gripping means may be provided adjacent to, but spaced apart from, the covering material.

Alternatively or in addition, the gripping means may include a pressure receiving surface provided within the housing. The gripping means may include one or more protrusions extending from the pressure receiving surface, through apertures provided at the exterior surface of the housing and towards the covering material. The airbag module may be adapted such that the pressure receiving surface receives a pressure caused by the inflator system during deployment of the airbag which causes the protrusions to move towards and at least contact the covering material.

The gripping means may include biasing means for biasing the pressure receiving surface towards the first position.

The gripping means may comprise one or more teeth, barbs or hooks. A plurality of teeth, barbs or hooks may be provided, arranged in an array. The number of teeth, barbs or hooks and/or the array configuration may be adapted to spread the gripping force to inhibit tearing of the covering material.

Alternatively, the gripping means may comprise one or more covering material contacting surfaces. Each contacting surface may be adapted to provide frictional contact with the covering material to inhibit relative movement between the contacting surface and the covering material.

The gripping means may be integral with the housing. The housing may be a plastic moulding. The housing may be formed by injection moulding.

Alternatively or in addition, the gripping means may be formed by working of the housing. The gripping means may be formed by deforming one or more portions of the housing to create one or more protrusions.

The gripping means may be adapted to grip the covering material at at least one location adjacent to the deployment seam to reduce elastic stretching of the covering material.

The recess may be provided at a side portion of the vehicle seat to provide a side airbag.

According to a second aspect of the present invention there is provided a method of forming a vehicle seat assembly comprising:

providing a vehicle seat comprising a rigid frame, one or more resilient portions and a covering material;

providing an openable deployment seam at a portion of the covering material;

providing a recess in the vehicle seat;

locating an airbag module within the recess, the module comprising a housing, an airbag and an inflator system; and

providing gripping means which is movable between a first position and a second position in which the portion of the covering material is restrained to assist deployment of the airbag through the deployment seam.

The method may include moving the gripping means from the first position to the second position during deployment of the airbag.

The method may include expanding the housing during deployment of the airbag such that a portion of the housing moves towards the covering material.

The method may include providing an opening, weakening feature, abutting edges or the like at the housing such that two portions of the housing move apart during deployment of the airbag.

The method may include providing a pressure receiving surface within the housing. The method may include providing one or more protrusions extending from the pressure receiving surface, through apertures provided at the exterior surface of the housing and towards the covering material. The method may include adapting the pressure receiving surface to receives a pressure caused by the inflator system during deployment of the airbag and to move towards and at least contact the covering material.

The method may include biasing the pressure receiving surface towards the first position.

The gripping means may comprise a plurality of teeth, barbs or hooks and the method may include arranging the plurality of teeth, barbs or hooks in an array so as to spread the gripping force to inhibit tearing of the covering material.

The method may include forming the gripping means as integral with the housing. The housing may be formed by injection moulding.

Alternatively or in addition, the method may include forming the gripping means by working the housing. The method may include deforming one or more portions of the housing to create one or more protrusions.

The method may include providing the recess at a side portion of the vehicle seat to provide a side airbag.

The above advantages and other advantages and features will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the attached figures the same reference numerals will be used to refer to the same components. In the following description various operating parameters and components are described for different constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting.

FIGS. 1 and 2show a vehicle seat assembly10which includes a vehicle seat12. The seat12comprises a rigid frame13(a portion of which is shown inFIGS. 2 to 5), resilient portions or foam padding14and a covering material16.

As shown inFIGS. 3 to 5, the seat12includes a side recess and an airbag module20is located within this recess. The airbag module20comprises a housing22, an airbag24and an inflator system26. The airbag module20is operable to deploy the airbag24to a location between an occupant sitting in the seat12and the adjacent body structure100of the vehicle102, as shown inFIGS. 1 and 2.

The covering material16includes a deployment seam18provided at a portion of the covering material16, this portion being near to the housing22. The deployment seam18is adapted to predictably tear open when under pressure from the expanding airbag24. Adjacent to the deployment seam18and bonded to the internal surface of the covering material16is a piece of foam19.

The housing22comprises an upper portion30and a lower portion32which move apart during deployment of the airbag24. The upper portion30is fixed to the frame13. An edge of each portion abut together at one side of the housing At the opposite side, the two portioned are connected by a hinge34. When the inflator system26is initiated, the expanding airbag24creates a pressure which forces the two portions apart, allowing the airbag24to continue to expand out of the housing22. The upper portion30does not move due to its attachment to the frame13but the lower portion32pivots outwards about the hinge34and therefore towards the covering material16.

The vehicle seat assembly10also includes gripping means. In this embodiment, the gripping means comprises a number of downwardly projecting teeth40which are linearly arranged at the housing22(only one tooth can be seen inFIG. 3). The housing22is a plastic injection moulding and the teeth40are formed during the moulding process.

The teeth40are provided at the lower portion32of the housing22. Therefore, deployment of the airbag24causes the teeth40to move from a first position to a second position in which the teeth40have moved closer to the covering material16.

The foam piece19is located at the covering material16at a position corresponding to the teeth40when they have moved closer to the covering material16.

In use, deployment of the airbag24causes the lower portion32to pivot outwards as previously described until the teeth40pierce into the foam piece19. This causes the teeth40, and therefore the housing22, and the foam piece19, and therefore the covering material16, to be attached at this location. Meanwhile, the airbag24has expanded out of the housing22and is acting on the deployment seam18. Initially (before a tear stress of the deployment seam18is reached), the covering material16around the deployment seam18responds elastically to this force.

In a conventional arrangement, a substantial amount of covering material16would be stretched, elastically absorbing the energy of the airbag24for a longer period and delaying the stress at the deployment seam18reaching the tear stress. The greater the area of the covering material16being stretched, the more elastic absorbing of the energy.

The invention, specifically the attachment of the teeth40and foam piece19, mitigates this. The covering material16is restrained at the attachment location which is near the deployment seam18. Therefore, less covering material16is stretched. The tear stress is therefore reached sooner, resulting in the opening of the deployment seam18to allow the airbag24to exit the seat12through the deployment seam18.

FIG. 4shows a second embodiment of the invention. Like features are provided with like reference numbers.

This embodiment is similar to the first except that the teeth40are arranged in an array comprising two dimensions (only the first row is visible inFIG. 4) at the exterior under-surface of the housing22. Also, the size and location of the foam piece19has been adapted to suit the array of teeth40.

The greater number of teeth40in this embodiment helps to spread the gripping force to inhibit tearing of the covering material16.

FIG. 5shows a third embodiment of the invention. Like features are provided with like reference numbers.

In this embodiment, the gripping means comprises a plate50having a pressure receiving surface52. The plate50is provided within the housing and so the pressure receiving surface52receives a pressure caused by the inflator system during deployment of the airbag24.

A number of protrusions or pins54extend from the plate50, through apertures provided at the housing22and towards the covering material16. The plate50is connected to the housing by springs56which bias the plate50towards the first position in which the pins54are still spaced from the covering material16.

In use, deployment of the airbag24again causes the lower portion32to pivot outwards. In addition to this, the plate50is moved outwards due to pressure. This combination causes the pins54to pierce and attach to the foam piece19. It is to be appreciated that, in alternative embodiments, only the outwards movement of the plate50could be used to cause the pins54to pierce and attach to the foam piece19. For instance, the lower portion32of the housing22could be attached to the frame13and restrained from moving (and the upper portion30could move upwards to allow the airbag24to exit the housing22).

FIG. 6shows a fourth embodiment of the invention. Like features are provided with like reference numbers.

FIG. 6(a) shows the airbag module20attached to the frame13of the seat12. In the figure, the most visible part of the airbag module20is the lower portion32of the housing22. In this embodiment, the housing22is formed from sheet steel.

The gripping means is formed by working the lower portion32of the housing22. The plane of the sheet steel is cut, for instance using a C cut. Then the material62within the cut is deformed out of plane to create a downwardly projecting hook60, as shown inFIG. 6(b). The end of the hook60may be filed to create a sharper profile. This is done at multiple locations to create a row or an array of hooks60.

The device of this embodiment works similarly to the first and second embodiments. Deployment of the airbag24causes the lower portion32to pivot outwards. This causes the hooks60to pierce and attach to the foam piece19. This limits stretching of the covering material16when acted upon by the expanding the airbag24.

Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention.