GB2334920A - Two part vehicle knee bolster - Google Patents

Abstract

A motor vehicle knee bolster comprises two spaced bolster panels 11, 12, one each side of a steering column 13 assembly, the two panels being substantially isolated and decoupled. The two panels may provide the same deformation response or they may provide a lateral variation in deformation response to applied force. Together with the steering column assembly the two panels may present a constant profile within the vehicle. A gap of 1-2 mm may be left between the panels and the steering column assembly or the panels may be attached to the steering column assembly by an easily frangible seal 14.

Description

A BOLSTER ARRANGEMENT The present invention relates to a bolster arrangement and more particularly to a bolster arrangement used within a motor vehicle in order to provide for safe occupant collision energy dissipation.

Provision of deformable or collapsible elements within a motor vehicle in order to reduce injury to an occupant of such a vehicle is now commonplace and indeed mandatory in some countries. The present invention relates principally to bolster arrangements about the motor vehicle driver's area.

Typically, as indicated schematically in the drawing and marked Prior Art, a bolster panel 1 is located adjacent a steering column assembly 2.

Thus, in a collision a driver's knees are presented to respective surfaces 3, 4 of the bolster panel 1 and the steering column assembly rides down in the direction of arrowhead A in contact with the driver's torso. The occupant's torso loading the column pushes the column down. The panel 1 is typically mounted upon crushable brackets or foam sections to achieve the necessary deformation in contact with an occupant's knees during a collision whilst the steering column assembly 2 typically rides down upon a telescopic type arrangement.

As depicted in the prior art drawing, it will be seen that the steering column assembly 2 generally protrudes through an aperture or channel 5 of the panel 1. Thus, during collision deformation the panel 1 eventually comes into contact with the assembly 2 whereupon further deformation is inhibited, ie. the bolster and/or column cannot achieve the required travel.

The objective of the collision deformation of panel 1 and displacement of assembly 2 is to absorb driver energy during the violent deceleration associated with a motor vehicle collision. In such circumstances it will be appreciated that the speed and range of panel 1 deformation and assembly 2 displacement are tuned to a particular motor vehicle configuration. If the energy dissipation achieved by panel 1 deformation and assembly 2 displacement is too severe, ie. static whilst the driver still presents significant collision force, it will be appreciated that that driver may be injured. Alternatively, the range and speed of panel 1 deformation and assembly 2 displacement must be controlled within acceptable motor vehicle packaging constraints, ie. long range of deformation and displacement may in theory be ideal but within a motor vehicle sufficient space for such deformation/displacement is not available. A practical range of deformation for panel 1 is normally 100 mm.

It will be noted the range of deformation in the panel 1 is generally displaced in line with the percussive force applied by the driver's knees whilst the assembly 2 is displaced at an angle. Thus, for the same range of deformation/displacement the assembly 2 will normally require a great distance of travel. Such differentiation between the panel 1 and the assembly 2 may create accommodation problems within a motor vehicle and precipitate transient orientation problems due to differences in displacement/deformation speed. Such problems can precipitate the collision contact problem described above with its potential for panel 1 diminution in displacement range and abrupt termination in bolster panel deformation.

The above-mentioned problems are particularly prominent within small motor vehicles where the degree of latitude with regard to component accommodation is limited by the inherent reduction in dimensions. It will be noted that typically in such small vehicles the steering column assembly 2 will be presented at a steep angle relative to the panel 1 compounding the deformation range and speed disparities between the bolster panel 1 and that assembly 2.

It is an object of the present invention to provide a bolster arrangement for a motor vehicle which substantially relieves the above-mentioned problems.

In accordance with the present invention there is provided a bolster arrangement for a motor vehicle, the arrangement comprising a first bolster panel and a second bolster panel arranged either side of a steering column assembly, said first and said second bolster panels, along with said steering column assembly, being laterally spaced to present substantially isolated and decoupled deformation therebetween when subjected to an applied percussive force.

The bolster panels and the steering column assembly may be arranged stylistically and in juxtaposed position to provide a desired consistent profile.

The bolster panels and the steering column assembly may be independently mounted within the motor vehicle.

The first and second bolster panels may have substantially the same deformation response to an equivalent applied percussive force.

The first and the second bolster panels may have a lateral variation in deformation in order to partially deflect any percussive force applied thereto.

The first and the second bolster panels may include an appropriate deformation response in order to deflect any applied percussive thereto downwards whilst said steering column assembly is arranged to relatively deflect any presented percussive force upwards relative to said panels.

An embodiment of the present invention will now be described by way of example only with reference to Figure 1 of the drawings, in which a schematic representation of a bolster arrangement is depicted.

In Figure 1 a bolster arrangement is depicted in schematic form. The arrangement comprises separate bolster panels 11, 12 either side of a steering column assembly 13. The panels 11, 12 are mounted independently using crushable brackets whilst the assembly 13 is typical and includes a telescopic displacement arrangement. Thus, when subjected to percussive forces as a result of collision with a driver or vehicle occupant, the panels 11, 12 are displaced or deformed in the direction of arrowheads X and Y whilst the steering column assembly 13 is displaced in the direction of arrow head Z.

The panels 11, 12 along with the steering column assembly 13 are laterally spaced within a motor vehicle to provide a desired consistent profile for styling purposes. However, in accordance with the present invention, the panels 11, 12 and assembly 13 are not laterally coupled and so present isolated deformation structures to applied percussive forces.

Thus, the depth or range of displacement or deformation along with the speed of such action with regard to each panel 11, 12 and assembly 13 is not influenced by the other panel and/or assembly.

With the bolster arrangement of the present invention, it will be appreciated that there is no lateral profile connection between the panels 11, 12 and the assembly 13 thus the range and speed of deformation as a result of percussive force applied by an occupant during collision can be accurately determined by a designer. In such circumstances appropriate materials and configurations can be determined in order to achieve the necessary deformation response. Thus, inconsistency of panel and steering column deformation fouling limiting the deformation range is eliminated.

Furthermore, within the assembly 13 isolated in terms of deformation from the panels 11, 12 , the angle of that assembly 13 does not effect deformation range of these panels 11, 12. It will be appreciated that the steering column assembly height is commonly adjustable within a motor vehicle to accommodate different driver's height and driving position. Such steer column height variations in the assembly 13 angle in accordance with previous prior art bolster assemblies described above inevitably alters the degree of deformation fouling between the steering column assembly and the bolster panel giving a variable operational performance.

The objective of bolster arrangement is to absorb driver energy during collision thus, as the range of displacement or deformation for each of the spaced sections 11, 12, 13 acceptable within a particular motor vehicle can be determined or allocated, it will be appreciated that the material and construction of the panels 11, 12 and the steering column assembly 13 can be specified within that acceptable displacement range without consideration of deformation/displacement fouling. A further advantage is that the panels 11, 12 along with assembly 13 can be independently specified for deformation response. Thus, the deformation range acceptable for each panel 11, 12 may be different and thus different materials or configurations in terms of brackets, ribbing material thickness and shaping may be specified for each panel 11, 12 reducing any compromise conditions necessary with regard to a single panel as depicted in the prior art.

As indicated above, the present invention has particular application in small motor vehicles where dimensions limit the range available for appropriate occupant energy absorption by deformation/displacement of panels 11, 12 and assembly 13. Furthermore, as indicated above, the steering column assembly 13 in such small vehicles is generally configured at a more acute steep angle such that lateral displacement equivalent to that of the panel 11, 12 is difficult to achieve in terms of range and speed of displacement. Such differentials between the panel and the steering column assembly displacement ranges and speeds of displacement /deformation leads to the prior art fouling problems, at least transiently, during occupant energy dissipation upon collision. Isolating deformation between the panels 11, 12 and the assembly 13 eliminates such fouling problems and so more accurate prediction of occupant energy dissipation as an applied percussive force on the panels 11, 12 and assembly 13 can be determined.

Typically, it may be that the panels 11, 12 along with the assembly 13 are arranged to deflect applied percussive force as a result of occupant collision. Thus, the assembly 13 could be arranged to have a more substantial upward displacement away from the occupant whilst the panels 11, 12 have a more substantial downward component in their deformation.

In order to maximise effective longitudinal displacement range of the bolster arrangement comprising the panels 11, 12 and assembly 13.

Furthermore, the panels 11, 12 could be provided with a lateral variation in deformation response in order to deflect outwards any applied percussive force upon the panels 11, 12 through an occupant's knees in order to spread such applied force into compartments of the motor vehicle where further deformation range may be achieved. However, energy dissipation may be more conveniently achieved by a more perpendicular application of the percussive force as a result of occupant collision with the panels 11, 12 and assembly 13.

The panels 11, 12 and assembly 13, as indicated above, provide a consistent profile for the motor vehicle in order to achieve desired styling.

However, as the panels 11, 12 and assembly 13 are substantially independent, it will be appreciated that an easily frangible seal may be desirable along proposed edges 14 in order to limit drumming, vibration noise and other detrimental features of independent juxtaposed components.

Typically, there will be a gap of 1-2 mm between the panels 11, 12 and the adjacent assembly 13 surface.

Although the panels 11, 12 along with the assembly 13 are isolated with respect to each other in terms of deformation and displacement response, it will be appreciated that the panels 11, 12 and assembly 13 are mounted within a motor vehicle to appropriate structural components such as the facia or bulkhead or cross car beam, etc. Thus, these panels 11, 12 and assembly 13 are integral within the vehicle in terms of positional stability during normal operation of the motor vehicle and only provide isolated potentially differential deformation/displacement response when subjected to an applied percussive force from an occupant during a motor vehicle accident.

The brackets used to mount the panels 11, 12 within the dashboard/bulkhead of a motor vehicle are those normally used with regard to prior art bolster panels. However, spacing and strength of the crushable brackets etc, will be determined in accordance with desired deformation/displacement response within a particular motor vehicle. Such spacing and deformation response of the brackets will be different to that of prior art bolster panels due to different loadings applied to smaller isolated panels 11, 12 in comparison with a single unitary panel used in previous bolster configurations. In addition, it will be appreciated that generally there will be different shaping and configuration between present panels 11, 12 and so differences in bracket mounting configuration and spacing between these panels 11, 12 to achieve the desired deformation response.

Normally, the panels 11,12 will be made from a plastics material which may be moulded as required to include features such as recesses, scoring or ribs in order to achieve the desired deformation response for each panel 11, 12.

The steering column assembly 13 will typically displace and deform using a telescopic mechanism. Thus, there will be no lateral bulging of the assembly 13 which may interfere with the panels 11, 12. Furthermore, the steering wheel of the steering column assembly 13 may be designed to deform to the most desirable configuration for energy dissipation of an occupant in collision therewith and in order to reduce penetrative injury of that occupant. In addition to telescopic deformation for the assembly 13, it will be appreciated that the assembly 13 could be designed to arc upwards in the direction of arrowhead B about a pivot point located internally behind the bolster arrangement. Such arcuate displacement again increasing the deformation range during occupant collision and, with appropriate resistance or drag to such arcuate deformation in the direction of arrowhead B, further occupant energy may be absorbed.

Those skilled in the art will appreciate that the objective of bolster arrangement deformation and displacement is to provide for gradual vehicle occupant energy dissipation upon collision and so reduce potential injury to that occupant. Within a motor vehicle normally there are several safety features including seatbelts in order to restrain that motor vehicle occupant.

These safety systems act in concert to provide for motor vehicle user safety.

However, it is necessary to test these safety systems independent to ensure occupant safety. Thus, in the present case the bolster arrangement must be adequate to achieve the desired level of occupant energy absorption. The increased predictability of deformation range and response provided by isolated panels 11, 12 and assembly 13 allows the motor vehicle designer to more consistently achieve the desired and required level of energy absorption through such panels 11, 12 and assembly 13. Thus, the designer is left with achieving the required energy absorption response through deformation/displacement through choice of material, configuration and crushable bracket mountings, etc, rather than over specification to account for unpredictable or variable inter-component fouling.

Claims (8)

1. CLAIMS 1. A bolster arrangement for a motor vehicle, the arrangement comprising a first bolster panel and a second bolster panel arranged either side of a steering column assembly, said first and said second bolster panels along with the steering column assembly being laterally spaced to present substantially isolated and decoupled deformation therebetween to an applied percussive force.
2. 2. An arrangement as claimed in Claim 1, wherein said first and said second bolster panel along with said steering column assembly are juxtaposed to provide a desired constant profile within a motor vehicle.
3. 3. An arrangement as claimed in Claim 1 or Claim 2, wherein said first and said second bolster panels along with said steering column assembly are independently mounted within a motor vehicle structure.
4. 4. An arrangement as claimed in Claim 1, 2 or 3, wherein said first and said second bolster panels have substantially the same deformation response through appropriate choice of material, configuration and mounting within a motor vehicle.
5. 5. An arrangement as claimed in any preceding claim, wherein said first and/or said second bolster panels are arranged to provide, in use, a lateral variation in deformation response to said applied percussive force.
6. 6. A bolster arrangement as claimed in any preceding claim, wherein said first and said second bolster panels are arranged to have a substantial downward deformation response to said applied percussive force whilst said steering column assembly is arranged to have a substantial upward deformation component to an applied percussive force.
7. 7. A bolster arrangement substantially as hereinbefore described with reference to the accompanying drawing.
8. 8. A motor vehicle including a bolster arrangement as claimed in any preceding claim.