GB2191449A

GB2191449A - Motor vehicle with occupant's protection system

Info

Publication number: GB2191449A
Application number: GB08614532A
Authority: GB
Inventors: Robert Frederick Else
Original assignee: Britax PMG Ltd
Current assignee: Britax PMG Ltd
Priority date: 1986-06-14
Filing date: 1986-06-14
Publication date: 1987-12-16
Also published as: GB8614532D0

Abstract

In a motor car 10, the steering wheel 18 and fascia 20 are mounted for movement horizontally towards and away from the front seats 14. A hydraulic ram 24 is arranged to move the steering wheel 18 and the fascia 20 rearwardly at a speed related to the instantaneous speed of the vehicle in response to impact on the front of the vehicle, and to move the steering wheel 18 and the fascia 20 forwardly in response to forward pressure on the steering wheel 18 or the fascia 20 at a speed related to the rate of deceleration of the seat. <IMAGE>

Description

SPECIFICATION Motor vehicle with occupant's protection system This invention relates to a motor vehicle having a forward facing seat, a structural member mounted in front of the seat for movement horizontally towards and away from the seat, a first sensor responsive to impact on the front of the vehicie, a second sensor responsive to forward pressure on the structural member and drive means for the structural member adapted to move the structural member rearwardly in response to the first sensor and to move the structural member forwardly in response to the second sensor.

Preferably the first sensor is arranged to cause rearward movement of the structural member at a speed related to the instantaneous speed of the vehicle.

The second sensor is preferably arranged to cause forward movement of the structural member at a speed related to the rate of deceleration of the seat.

The drive means for the structural member may be pneumatic or hydraulic. When such drive means are used, the second sensor may be arranged to respond to fluid pressure therein and can conveniently take the form of a relief pressure valve arranged to open by a progressively increasing amount dependent on the extent to which the fluid pressure in the drive means exceeds a threshold level.

An embodiment of the invention will now be described, by way of example, in which: Figure 1 is a schematic side sectional view of a motor car fitted with a system in accordance with the invention, shortly before impact with a stationary object; Figure 2 is a schematic view similar to Fig.

1 showing the vehicle shortly after impact; Figure 3 is a schematic view similar to Figs.

1 and 2, showing the vehicle at a slightly later stage after impact.

Fig. 1 shows a motor car 10 about to collide with a wall 12. The car 10 has a seat 14 for the driver 16 and a steering wheel 18 and fascia 20 mounted on a bulkhead 22 by means of a hydraulic ram 24. Supply of hydraulic fluid to the ram 24 is controlled by first and second sensors (not shown) responsive respectively to vehicle speed and to forward thrust on the steering wheel 18 and the fascia 20.

The operation of the system is as follows.

When the front bumper 26 of the vehicle makes contact with the wall 12, the resulting high frequency shock waves are detected by the first sensor which then causes hydraulic fluid to be supplied to the ram 24 at a rate such that the steering wheel 18 and fascia 20 move rearwardly relative to the bulkhead 22 at a speed equal to the instantaneous vehicle speed, i.e. so that they remain substantially stationary relative to the wall 12. As the front portion 28 of the vehicle starts to crumple, the seat 14 and driver 16 continue to travel forwardly until the driver's body makes contact with the steering wheel 18 as illustrated in Fig. 2. The increased forward thrust on the ram 24 is detected by the second sensor which then overrides the first sensor and allows hydraulic fluid to bleed from the ram 24 at a rate such as to minimise the maxiumum deceleration of the body of the driver 16.The final position of the car 10 and driver 16 is shown in Fig. 3, the steering wheel 18 and fascia 20 having returned to its original position relative to the bulkhead 22.

The rate at which hydraulic fluid is allowed to bleed from the ram 24 as the car moves from the position shown in Fig. 2 to the position shown in Fig. 3 is chosen in accordance with the absorption characteristic of the front part 28 of the car, and is arranged to be varied in accordance with initial vehicle speed and rate of deceleration. The latter rate, of course, would be different if the car 10 was in collision with a moving object rather than with a stationary object such as the wall 12.

The driver 16 is thus offered the deceleration distance indicated by the arrow A in Fig.

3. If the steering wheel 18 had remained stationary the decelaration distance would have been less than that indicated by the arrow B because the driver 16 would have moved somewhat further forwards before making contact with the steering wheel 18.

The foregoing system can also be used to adjust the position of the steering wheel 18 and the instruments on the fascia 20 relative to the seat 14 so as to make provision for different sized drivers.

A system in accordance with the invention can be arranged to cater for oblique crashes by providing two separately controlled rams at opposite ends of the fascia 20.

1. A motor vehicle having a forward facing seat, a structural member mounted in front of the seat for movement horizontally towards and away from the seat, a first sensor responsive to impact on the front of the vehicle, a second sensor responsive to forward pressure on the structural member and drive means for the structural member adapted to move the structural member rearwardly in response to the first sensor and to move the structural member forwardly in response to the second sensor.

2. A vehicle according to claim 1 or 2, wherein the first sensor is arranged to cause rearward movement of the structural member at a speed related to the instantaneous speed of the vehicle.

3. A vehicle according to claim 1 or 2, wherein the second sensor is arranged to cause forward movement of the the structural

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Motor vehicle with occupant's protection system This invention relates to a motor vehicle having a forward facing seat, a structural member mounted in front of the seat for movement horizontally towards and away from the seat, a first sensor responsive to impact on the front of the vehicie, a second sensor responsive to forward pressure on the structural member and drive means for the structural member adapted to move the structural member rearwardly in response to the first sensor and to move the structural member forwardly in response to the second sensor. Preferably the first sensor is arranged to cause rearward movement of the structural member at a speed related to the instantaneous speed of the vehicle. The second sensor is preferably arranged to cause forward movement of the structural member at a speed related to the rate of deceleration of the seat. The drive means for the structural member may be pneumatic or hydraulic. When such drive means are used, the second sensor may be arranged to respond to fluid pressure therein and can conveniently take the form of a relief pressure valve arranged to open by a progressively increasing amount dependent on the extent to which the fluid pressure in the drive means exceeds a threshold level. An embodiment of the invention will now be described, by way of example, in which: Figure 1 is a schematic side sectional view of a motor car fitted with a system in accordance with the invention, shortly before impact with a stationary object; Figure 2 is a schematic view similar to Fig. 1 showing the vehicle shortly after impact; Figure 3 is a schematic view similar to Figs. 1 and 2, showing the vehicle at a slightly later stage after impact. Fig. 1 shows a motor car 10 about to collide with a wall 12. The car 10 has a seat 14 for the driver 16 and a steering wheel 18 and fascia 20 mounted on a bulkhead 22 by means of a hydraulic ram 24. Supply of hydraulic fluid to the ram 24 is controlled by first and second sensors (not shown) responsive respectively to vehicle speed and to forward thrust on the steering wheel 18 and the fascia 20. The operation of the system is as follows. When the front bumper 26 of the vehicle makes contact with the wall 12, the resulting high frequency shock waves are detected by the first sensor which then causes hydraulic fluid to be supplied to the ram 24 at a rate such that the steering wheel 18 and fascia 20 move rearwardly relative to the bulkhead 22 at a speed equal to the instantaneous vehicle speed, i.e. so that they remain substantially stationary relative to the wall 12. As the front portion 28 of the vehicle starts to crumple, the seat 14 and driver 16 continue to travel forwardly until the driver's body makes contact with the steering wheel 18 as illustrated in Fig. 2. The increased forward thrust on the ram 24 is detected by the second sensor which then overrides the first sensor and allows hydraulic fluid to bleed from the ram 24 at a rate such as to minimise the maxiumum deceleration of the body of the driver 16.The final position of the car 10 and driver 16 is shown in Fig. 3, the steering wheel 18 and fascia 20 having returned to its original position relative to the bulkhead 22. The rate at which hydraulic fluid is allowed to bleed from the ram 24 as the car moves from the position shown in Fig. 2 to the position shown in Fig. 3 is chosen in accordance with the absorption characteristic of the front part 28 of the car, and is arranged to be varied in accordance with initial vehicle speed and rate of deceleration. The latter rate, of course, would be different if the car 10 was in collision with a moving object rather than with a stationary object such as the wall 12. The driver 16 is thus offered the deceleration distance indicated by the arrow A in Fig. 3. If the steering wheel 18 had remained stationary the decelaration distance would have been less than that indicated by the arrow B because the driver 16 would have moved somewhat further forwards before making contact with the steering wheel 18. The foregoing system can also be used to adjust the position of the steering wheel 18 and the instruments on the fascia 20 relative to the seat 14 so as to make provision for different sized drivers. A system in accordance with the invention can be arranged to cater for oblique crashes by providing two separately controlled rams at opposite ends of the fascia 20. CLAIMS

3. A vehicle according to claim 1 or 2, wherein the second sensor is arranged to cause forward movement of the the structural member at a speed related to the rate of deceleration of the seat.

4. A vehicle according to claim 1, 2 or 3, having fluidic drive means for the structural member, the second sensor being arranged to respond to fluid pressure therein.

5. A vehicle according to claim 4, wherein the second sensor is a pressure valve arranged to open by a progressively increasing amount dependent on the extent to which the fluid pressure in the drive means exceeds a threshold level.