GB2335631A

GB2335631A - Sensor arrangement

Info

Publication number: GB2335631A
Application number: GB9806621A
Authority: GB
Inventors: David Roy Saville; Timothy Scott
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1998-03-27
Filing date: 1998-03-27
Publication date: 1999-09-29
Also published as: GB9806621D0

Abstract

A collision sensor arrangement for a motor vehicle comprises a collision sensor 2 for operative connection to an airbag in a side of the vehicle. The sensor 2 is secured to a structural element 6 of a side of the vehicle by means of a substantially rigid spacing member 4 whereby the sensor 2 is less likely to be damaged in the event of a side collision. The sensor 2 is substantially prevented from vertical movement relative to the floor 16 of the vehicle, e.g. by locating a tab 10 of the spacing member 4 in a recess 12 in a cross member 14, whereby the risk of accidental triggering of a side airbag in the event of a vertical impact is reduced.

Description

2335631 SENSOR ARRANGEMENT The present invention relates to a sensor

arrangement for use in triggering the deployment of an airbag in a motor vehicle in the event of an impact, notably a side impact, and to a motor vehicle which includes such a sensor arrangement.

There are particular problems associated with the triggering of "side impact" airbags, in contrast to "front impact" airbags. In the event of a frontal collision there is a lot of metal between the driver and the point of impact, which provides a crumple zone. The crumple zone helps reduce the effect of an impact on a driver or passenger, and increases the time available for deployment of an airbag. In the case of a side impact there may be much less space between the point of impact and an occupan t of the vehicle, and little or no crumple zone. There is therefore very little time for a collision sensor to decide whether or not to deploy an airbag.

The sensor used must react very quickly in response to lateral impact, but it must not trigger unnecessarily, for example in response to vertical impact such as may occur when a vehicle hits a bump or a pot-hole, or when a stone hits the underside of the vehicle.

It is known to secure a side impact sensor to a side panel of a door (see for example European Patent publication number 0 616 926) or on a cross member in the floor of a vehicle (see for example European Patent publication number 0 536 624). Securing the sensor to the side of the vehicle renders it liable to be damaged by a side impact, and securing the sensor to the floor makes it particularly sensitive to vertical impacts such as stones hitting the underside of the vehicle, or to vehicle grounding on rough roads.

According to a first aspect of the present invention there is provided a motor vehicle which includes a collision sensor arrangement comprising collision sensor means for operative connection to an airbag in a side of the vehicle, secured to a structural element of a side of the vehicle by means of a substantially rigid spacing member, the sensor neans being substantially prevented from vertical movement relative to the floor of the vehicle.

By spacing the sensor f rom the side of the vehicle, it can be less likely to suf f er damage in the event of a side collision. Preventing the sensor from vertical movement reduces the risk of accidental and unwanted triggering of a side airbag in the event of a vertical impact, for example from driving over a pot-hole or from a stone hitting the underside of the vehicle. The risk of accidental triggering of an airbag by vibrations in a vertical plane is also reduced.

The collision sensor arrangement nay be manufactured and sold as an addon item for a vehicle. Another aspect of the present invention therefore provides a collision sensor arrangement for a motor vehicle, the arrangement comprising collision sensor means for operative connection to an airbag in a side of the vehicle, secured to a structural element of a side of the vehicle by means of a substantially rigid spacing member, t-he sensor means, when the arrangement is installed in a vehicle, being substantially prevented from vertical movement relative to the f loor of the vehicle.

In a preferred embodiment, the spacing member comprises a bracke'L-. or mounting plate, for example a metal plate, which is secured along one edge to a side rocker of the vehicle. The plate may be immovably connected to the side rocker, for example by bolts, screws or rivets, or it may be pivotally connected in such a manner that angular ro4Cations of the rocker are transmitted less or not at all to the sensor. Such a pivotal connection may serve to transmit forces only in one particular direction.

The design of the plate will depend on which factors are considered most important for a particular vehicle. For example, if a resonant frequency above 300 Hz is desired, the plate may be formed from a composite sandwich of ribbed steel, perhaps with holes to reduce its mass. If optimal foot package space is important, the plate may be formed from a thin, stiff, light material.

Rocker or B-pillar sensor locations may be in the crush zone for poletype impacts; however if a pole contact is not adjacent to the sensor there may be a delay in transmission of the crash signal. It is therefore preferred that the plate is rigid, to allow similar high signal levels in crush zone sensors but for a wider range of pole contac4.-- points on the vehicle side.

The sensor is preferably disposed between the carpet and the floor of the vehicle. In many vehicles a mat is disposed between the carpet and the floor, for reducing road and other noise. The mat is typically made of a felted material and is known as an NVH ("noise, vibration, harshness"). The sensor may be located in a cut-out of the NVH, or the sensor may be located on top of the NVH, which will be compressed to accommodate the sensor.

To reduce the chance of accidental deployment of the side airbag, the sensor may be protected from accidental collisions within the vehicle by a suitable shield or protective element.

The bracket preferably extends from the side rocker to a location under a vehicle seat. The bracket may be substantially isolated from vertical movement or vibration by providing the bracket with a tab which locates in a fixed member of the vehicle, for example a suitably shaped recess in a seat crossmenber.

The invention will now be described further, by way of example, with reference to the following drawing in which, Figure 1 is an x-ray perspective view of a sensor arrangement in accordance with the present invention; and Figure 2 is a sectional view along the line I-1 of Figure 1.

The arrangement shown in Figure 1 comprises a side satellilte sensor 2 which is rigidly connected to a metal bracket 4. The bracket 4 has a flange 8 at one end, and the flange 8 is connected by pivot means 24 to a side rocker 6 of a motor vehicle. The bracket 4 is provided with a lateral tab 10 disposed through an isolator grommet in a recess 12 in a crossmember 14 of a vehicle seat. The recess 12 is dimensioned so that vertical movement, or vibration in a vertical plane, of the bracket 4 is substantially prevented. The bracket 4 is disposed under a seat track 20, above a side rail 18.

The sensor 2 is located between the carpet 26 and the f loor 16 of the vehicle, in a cut-out portion or a compressed portion of the NVH 22, as best shown in Figure 2. The NVH is optionally provided with bitumen or the like, to stick it to the f loor. The sensor 2 is of conventional construction well known to those skilled in the art. It is programmed with an algorithm to detect deceleration and various noise freauencies resulting from impact of the vehicle. According to the instant value of the detected deceleration and/or the detected noise frequency the sensor will make a nearinstantaneous decision whether to deploy an associated side impact airbag.

Because the sensor 2 is located away f rom the side rocker 6 it is less prone to damage in the event of a side impact with the side rocker. By preventing vertical movement of the sensor 2, the sensor is made less prone to triggering in the event of a stone or the like striking the underside of the vehicle.

Alternatively, the sensor may comprise simply a crash pulse recorder which sends a signal to a separate processing unit at an appropriate location. The use of such a separate processing unit would permit the use of only a single central processor instead of a separate processor for each sensor.

Claims

1 - A motor vehicle which includes a collision sensor arrangement comprising collision sensor means for operative connection to an airbag in a side of the vehicle, secured to a structural element of a side of the vehicle by means of a substantially rigid spacing member, the sensor means being substantially prevented from vertical movement relative to the floor of the vehicle.

2. A motor vehicle as claimed in claim 1, wherein the spacing member comprises a bracket or mounting plate for securing the spacing member along one edge to a 15 side rocker of the vehicle.

3. A motor vehicle as claimed in claim 1 or claim 2, wherein the spacing member is pivotally mounted to a side rocker of a vehicle.

4. A motor vehicle as claimed in any one of the preceding claims, wherein the spacing member is provided with a tab which is secured in a crossmember of the vehicle.

5. A motor vehicle as claimed in claim 5, wherein the tab is secured in a crossnember of a seat of the vehicle.

6. A motor vehicle as claimed in any one of the preceding claims, wherein the sensor means is disposed beneath a seat of the vehicle.

7. A motor vehicle as claimed in any one of the 35 preceding claims, wherein the sensor means is 3 sandwiched between the vehicle carpet and the floor of the vehicle.

8. A motor vehicle which includes a collision sensor arrangement substantially as herein described with reference to or as shown in the drawing.

9. A collision sensor arrangement f or a motor vehicle, the arrangement comprising collision sensor means for operative connection to an airbag in a side of the vehicle, secured to a structural element of a side of the vehicle by means of a substantially rigid spacing member, the sensor means, when the arrangement is installed in a vehicle, being substantially prevented from vertical movement relative to the floor of the vehicle.

10. A collision sensor. arrangement as claimed in claim 9, wherein the spacing member comprises a bracket or mounting plate for securing the spacing member along one edge to a side rocker of a vehicle.

11. A collision sensor arrangement as claimed in claim 9 or claim 10, wherein the spacing member is provided with means for pivotally mounting it to a side rocker of a vehicle.

12. A collision sensor arrangement as claimed in any one of claims 9 to 11, wherein the spacing member is provided with a tab for securing in a vehicle component to substantially prevent vertical movement of the sensor means.

13. A collision sensor arrangement for a motor vehicle substantially as herein described with reference to or - a - as shown in the drawing.