GB2335521A

GB2335521A - Vehicle roll sensor

Info

Publication number: GB2335521A
Application number: GB9805690A
Authority: GB
Inventors: Jonas Bargman; Dion Kruse
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1998-03-17
Filing date: 1998-03-17
Publication date: 1999-09-22
Anticipated expiration: 2018-03-17
Also published as: GB2335521B; WO1999047383A1; AU2967299A; GB9805690D0

Abstract

A safety arrangement is provided in a motor vehicle. The safety arrangement comprises a roll sensor apparatus to sense conditions indicative of a roll-over accident to provide an output signal(4) to trigger actuation of a safety device(6). The roll sensor apparatus is responsive to both an angular parameter such as angular speed of the vehicle (#x)(1) - for example, whether the angular speed of the vehicle exceeds a threshold(3) and also responds to the lateral acceleration (ay)(2) - again comparing the latter acceleration with a threshold(5). One or both of the thresholds used for comparison purposes may be a function of another parameter of the vehicle, or may be fixed thresholds.

Description

2335521 DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO A SAFETY

ARRANGEMENrg THE PRESENT INVENTION relates to a safety arrangement and more particularly relates to a safety arrangement to be incorporated into a motor vehicle.

A substantial number of people each year are injured or killed in motor vehicle accidents in which the vehicle rolls completely or partially over. Accidents in which a vehicle rolls by at least 90' relative to its longitudinal axis are known as "roll-over accidenW. Roll-over accidents are the cause of a substantial proportion of all motor vehicle fatalities each year, even though rollover accidents only make up a relatively small proportion of the accidents that occur. Most of the injuries are in the head/face region, and in most cases are due to contact with the ground, due to full or partial ejection. Although the risk of injury is reduced by wearing a seat belt, nevertheless, in any roll over accident, the risk of injury is very high.

A roll-over accident may be initiated by various mechanisms but, in particular, may be initiated by the vehicle sliding into a curb (or other "solid" object) or sliding on a friction plane, such as soil. In such cases a lateral force acts on the wheels of the vehicle below the centre of gravity. Thus a torque is created that might "trip" the vehicle into a roll-over, and this type of accident 2 may be called a "tripped roll-over" accident. These tripped roll over accidents constitute a substantial proportion of all roll-over accidents.

Another type of roll-over accident occurs when the vehicle moves, possibly with a sliding action, into a region where the ground slopes. An example of this is where a vehicle inadvertently moves towards a ditch provided at the side of the road. In such a situation, two of the wheels on one side of the vehicle may temporarily be located above the sloping region of the ground or, in other cases, whilst one wheel on the side of the vehicle where the ground slopes may be in contact with the ground, the other wheel will be in the air. In such a case, a vertical force, provided by gravity, creates a torque that might cause a roll-over.

It has been proposed to provide motor vehicles with a so-called "inflatable cu'. The inflatable curtain is a restraint system in the form of an air-bag that is initially located in the roof of the motor vehicle just above the door opening, the air-bag being adapted, upon inflation, to form a substantially rigid curtain located ad acent the side windows of the vehicle. The air-bag prevents the head of the occupant from passing through the window opening. It is now thought that an inflatable curtain could be used to prevent occupant ejection, and hence prevent injuries due to contact with the ground, in a roll over accident.

For such an arrangement to be feasible, an appropriate triggering arrangement is required, and the present invention seeks to provide a safety arrangement which incorporates an appropriate triggering system.

It has been proposed to provide a sensor arrangement to sense a roll-over accident (see GB-A-2,314,187) in which the generation of a triggering signal is 3 dependent upon the angular speed of the vehicle, and also the instantaneous angle of rotation of the vehicle. Whilst an arrangement of this type does have some value, for example in the case of a slope rollover, it is now felt that if a safety device needs to be deployed very rapidly, then a sensor arrangement which uses this type of algorithm will not respond sufficiently rapidly. In other words, the arrangement is not able to distinguish "roll" from "not roll" early enough to deploy the safety device in time in certain types of accident including a tripped roll-over accident.

Also, of course, if angular speed is determined by using an angular speed sensor, and if the angle of roll is determined by integrating the output from the angular speed sensor, there is a risk that an inadvertent deployment of the safety device might arise if there is an error in the angular speed sensor.

According to this invention there is provided a safety arrangement in a motor vehicle, the safety arrangement comprising a roll sensor apparatus adapted to sense conditions indicative of a roll-over accident, to provide an output signal when a roll of the vehicle is anticipated or occurs, to trigger actuation of a safety device to provide protection for an occupant of the vehicle during a roll-over accident, the roll sensor apparatus being responsive to both an angular parameter such as the angle of roll (ct,,) of the vehicle or angular speed of the vehicle (c).) around the longitudinal axis thereof, and the lateral acceleration (ay) of the vehicle.

Preferably the roll sensor apparatus comprises an angular speed sensor to measure the angle of roll (ctx) andlor angular speed (co,,) and an accelerometer to measure the lateral acceleration (ay).

4 Conveniently the roll sensor apparatus is adapted so that the triggering signal is generated only if the angle of roll (a,) or the angular speed (o),,) exceeds a predetermine threshold, and the lateral acceleration (ay) also exceeds a predetermined threshold.

Advantageously the threshold for angle of roll (oc,,) or angular speed (co,,) is a constant.

Alternatively the threshold for angle of roll (cc,,) or angular speed (c), is a function of at least one other parameter.

Conveniently the threshold for the angular speed (co,,) is a function of the roll angle (a,,).

In one embodiment the threshold for angle of roll (cc,,) or angular speed (co,,) is a function of lateral acceleration (ay).

It is envisaged that in one embodiment the threshold for lateral acceleration is a constant.

Alternatively the threshold for lateral acceleration is a function of at least one parameter.

In a preferred embodiment of the invention the safety device comprises an inflatable side curtain- In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a block diagram of one embodiment of the invention, FIGURE 2 is a block diagram of another embodiment of the invention, and FIGURE 3 is a block diagram of another embodiment of the invention, Referring initially to Figure 1 of the accompanying drawings, a safety arrangement in accordance with the present invention comprises a sensor 1 adapted to sense the angle of roll ct,, or the angular speed co,, of a motor vehicle about the longitudinal axis of the vehicle. The arrangement also comprises a sensor 2 adapted to sense the lateral acceleration ay of the motor vehicle, that is to say the acceleration of the vehicle in a direction which is horizontal and which is substantially perpendicular to the longitudinal axis of the vehicle.

The angular speed sensor 1 is connected to a processor 3 where the instantaneous angle of roll ot. or angular speed co, is compared with a threshold such as an angular speed threshold (ol. In this example, if the instantaneous angular speed co,, exceeds the threshold such as an angular speed c) 1, a signal is passed from the processor 3 to an AND gate 4.

The output of the lateral acceleration sensor 2 is passed to a processor 5 where the lateral acceleration ay is compared with a threshold value a,. If the instantaneous lateral acceleration ay exceeds the threshold value ai. then a signal is passed from the processor 5 to the AND gate 4.

6 When the AND gate 4 receives signals from both the processor 3 and the processor 5, an output signal is generated which is passed to a safety device 6, to actuate the safety device. The safety device 6 is adapted to protect an occupant of a motor vehicle during a roll over accident. The safety device may comprise an inflatable curtain in the form of an airbag which, when inflated, is located adjacent the side windows of the motor vehicle in order to minimise the risk of the head of the occupant of the vehicle passing through the window opening. Alternatively the safety device may comprise, for example, a seat belt pre-tensioner.

It is to be noted that in the arrangement illustrated in Figure 1, the safety device is activated only if the angle of roll (xx and/or angular speed cox exceeds a predetermined threshold, and if lateral acceleration ay also exceeds a certain threshold. The thresholds could be constant thresholds or could be functions of other parameters. Thus, for example, the threshold for angular acceleration cox might be a function of the lateral acceleration, ay and/or the roll angle a..

Consequently the arrangement of Figure 1 is a safety arrangement which comprises a roll sensor apparatus adapted to sense conditions indicative of a roll over accident. An output signal is provided when a roll of the vehicle is anticipated, or when a roll-over actually occurs. the output signal triggers activation of a safety device to provide protection for the occupant of the vehicle. The roll sensor apparatus is responsive to both an angular parameter, such as the angle of roll ct,, of the vehicle or angular speed of the vehicle CO, and also the lateral acceleration ay of the vehicle.

7 Figure 2 illustrates an alternative arrangement in accordance with the invention, where some parts are identical with the parts described above, these parts being identified by identical reference numbers.

In the arrangement of Figure 2, a processor 7 is provided adapted to receive signals from the angle of roll or angular speed sensor 1 and the lateral acceleration sensor 2. In the processor 7, the instantaneous angle of roll or angular speed co,,, is compared with a threshold value, such as the value col(ay) which is a threshold value which is a function of the instantaneous lateral acceleration. The output of the sensor is provided directly to the safety device 6, to actuate the safety device.

It is to be appreciated that, in a fluther embodiment, as shown in Figure 3, (where again the same reference numerals are used for components that have been described above), the output of the angle of roll or angular speed sensor 1 is fed to a processor 7 while the output of the lateral acceleration sensor is fed to a processor 5 and also to the processor 7.

In the processor 7, the angle of roll, or in this example the instantaneous angular speed co,, is compared with a threshold value col (ay) which is a function of the instantaneous lateral acceleration. In the processor 5, the instantaneous lateral acceleration ay is compared with a threshold value a,. This threshold value may be fixed or may be a function of a parameter such as roll angle (a,,). Outputs of the processors 5 and 7 are fed to the AND gate 4, to generate an output signal 2 to deploy the safety device 6.

In utilising embodiments of the invention, it is possible to use a relatively low threshold value for angle of roll or angular velocity, since triggering is not only dependent upon angle of roll or angular velocity or the 8 output of the angular speed sensor. Instead, in embodiments of the invention it is necessary, for activation of the safety device to occur, for there to be a predetermined minimum angle of roll or angular speed, and also a predetermined lateral acceleration.

9

Claims

CLAIMS:

1. A safety arrangement in a motor vehicle, the safety arrangement comprising a roll sensor apparatus adapted to sense conditions indicative of a roll-over accident, to provide an output signal when a roll of the vehicle is anticipated or occurs, to trigger actuation of a safety device to provide protection for an occupant of the vehicle during a roll-over accident, the roll sensor apparatus being responsive to both an angular parameter such as the angle of roll (cc,) of the vehicle or angular speed of the vehicle (cox) around the longitudinal axis thereof, and the lateral acceleration (ay) of the vehicle.

2. A safety arrangement according to Claim 1 wherein the roll sensor apparatus comprises an angular speed sensor to measure the angle of roll (ax) and/or angular speed (coj and an accelerometer to measure the lateral acceleration (ay).

3. An arrangement according to Claim 1 or Claim 2, wherein the roll sensor apparatus is adapted so that the triggering signal is generated only if the angle of roll (cc,,) or the angular speed (cox) exceeds a predetermined threshold, and the lateral acceleration (ay) also exceeds a predetermined threshold.

4. An arrangement according to Claim 3 wherein the threshold for angle of roll or angular speed is a constant.

5. An arrangement according to Claim 3 wherein the threshold for angle of roll (oQ or angular speed (coj is a function of at least one other parameter.

6. An arrangement according to Claim 5 wherein the threshold for the angular speed (co,) is a function of the roll angle (a,,).

7. An arrangement according to Claim 5 wherein the threshold for angle of roll (a,,) or angular speed (co,) is a function of lateral acceleration (ay).

8. An arrangement according to any one of Claims 3 to 7 wherein the threshold for lateral acceleration is a (ay) constant.

9. An arrangement according to any one of Claims 3 to 7 wherein the threshold for lateral acceleration (ay) is a function of at least one parameter.

10. A safety arrangement according to any one of the preceding Claims wherein the safety device comprises an inflatable side curtain.

11. A safety arrangement substantially as herein described with reference to and as shown in Figure 1.

12. A safety arrangement substantially as herein described with reference to and as shown in Figure 2.

13. A safety arrangement substantially as herein described with reference to and as shown in Figure 3.

14. Any novel feature or combination of features disclosed herein.