Method for operation of a safety arrangement in a vehicle

1. A method for operation of a safety arrangement in a vehicle, the safety arrangement comprising a seat belt, a seat belt retractor and at least one seat position adjustment arrangement for position adjustment of a seat of the vehicle and/or a portion of the seat, the method comprising:

retracting the seat belt by the seat belt retractor with a retraction force;

displacing the seat and/or the portion of the seat prior to a crash, such that a displacement force acts on the seat belt; and

adapting the pre-crash displacement and the retraction of the seat belt to each other by ascertaining that a combined seat belt force comprising the retraction force and the displacement force does not exceed a selectable level.

2. The method according to claim 1 wherein the adapting comprises stopping or slowing down the pre-crash displacement of the seat or the portion of the seat if determined that the combined seat belt force is about to reach the selectable level.

3. The method according to claim 1 wherein the adapting comprises releasing the seat belt during the pre-crash displacement, such that the releasing at least partly corresponds to a tightening of the seat belt caused by the pre-crash displacement of the seat or the portion of the seat.

4. The method according to claim 1 wherein the adapting comprises first starting the pre-crash displacement, and at a later point of time performing the retraction of the seat belt.

5. The method according to claim 4 wherein the adapting comprises performing the retraction simultaneously with a part of the pre-crash displacement.

6. The method according to claim 1 wherein the pre-crash displacement comprises displacing the seat in relation to a body of the vehicle and/or displacing a seat back in relation to a seat squab.

7. The method according to claim 1 wherein the combined seat belt force is monitored by determining if the seat belt is actually being retracted when the seat belt retractor is activated.

8. The method according to claim 1 wherein the selectable level of the combined seat belt force is selectable based on vehicle occupant data.

9. A safety arrangement for a vehicle having a seat, the safety arrangement comprising:

a seat belt;

a seat belt retractor adapted for retraction of the seat belt with a retraction force;

at least one seat position adjustment arrangement adapted for a pre-crash displacement of the seat and/or a portion of the seat, the pre-crash displacement resulting in a displacement force acting on the seat belt;

a first sensor for determining a combined seat belt force acting on the seat belt, the combined seat belt force comprising the retraction force and the displacement force; and

a processor for adapting the pre-crash displacement and the retraction of the seat belt to each other by ascertaining that the combined seat belt force does not exceed a selectable level.

10. The safety arrangement according to claim 9 wherein the at least one seat position adjustment arrangement comprises a seat back inclination adjustment arrangement adapted to displace a seat back of the seat.

11. The safety arrangement according to claim 9 wherein the first sensor comprises a sensor for determining pulled out length of the seat belt.

12. The safety arrangement according to claim 9 wherein the first sensor comprises a sensor for determining speed of a motor of the seat belt retractor.

13. The safety arrangement according to claim 9 further comprising a second sensor for determining a position of the seat, to which the seat belt is associated, or for determining a position of a portion of the seat.

14. The safety arrangement according to claim 9 further comprising a system for detecting a collision or an imminent collision involving the vehicle.

15. A vehicle comprising the safety arrangement according to claim 9 .

16. A safety arrangement for a vehicle having a seat, a seat belt associated with the seat and a seat belt retractor adapted for retraction of the seat belt with a retraction force, the safety arrangement comprising:

at least one seat position adjustment arrangement adapted for a pre-crash displacement of the seat and/or a portion of the seat, the pre-crash displacement resulting in a displacement force acting on the seat belt;

a first sensor for determining a combined seat belt force acting on the seat belt, the combined seat belt force comprising the retraction force and the displacement force; and

a processor for adapting the pre-crash displacement and the retraction of the seat belt to each other by ascertaining that the combined seat belt force does not exceed a selectable level.

17. The safety arrangement according to claim 16 wherein the at least one seat position adjustment arrangement comprises a seat back inclination adjustment arrangement adapted to displace a seat back of the seat and/or an arrangement for positioning the seat in relation to a body of the vehicle.

18. The method according to claim 1 further comprising determining pulled out length of the seat belt using a sensor.

19. The method according to claim 1 further comprising determining speed of a motor of the seat belt retractor using a sensor.

20. The method according to claim 1 further comprising sensing position of the seat or sensing position of the portion of the seat.