DE102022200951A1 - Method for activating a vehicle occupant restraint system and vehicle occupant restraint system - Google Patents

Abstract

The invention relates to a method for activating a vehicle occupant restraint system (2), in which it is recognized that a collision of a vehicle (12) is imminent with a probability of <90%, with a collision time (tA) being precalculated and occupant parameters being recorded, with relation a seat angle (α) is detected on at least one vehicle seat (14) occupied by a vehicle occupant (10) and it is recognized that this seat angle (α) is greater than a vehicle-specific standard seat angle αs= [105° - 115°]. The seat angle (α) is then reduced, with the seat angle (α) being reduced within a period of no earlier than 1000 ms before the calculated impact time (tA). The invention also relates to a vehicle occupant restraint system (22) which is designed in particular to carry out the method.

Description

The invention relates to a method for activating a vehicle occupant restraint system and a vehicle occupant restraint system in which this method is carried out in particular.

In the case of automated or autonomous driving, a driver of a vehicle who, as a vehicle occupant, occupies a vehicle seat within the vehicle, no longer has to constantly monitor the vehicle itself or a system controlling the vehicle. As a result, the driver can assume a position on the vehicle seat that is comfortable for him while the vehicle is being driven. For example, the driver can put the vehicle seat in a sleeping position in order to rest while driving.

However, such random positions of the vehicle occupants while the vehicle is in motion mean that known elements of vehicle occupant restraint systems such as airbag bags that deploy from the steering wheel or seat belts can no longer be effective or can no longer be optimally effective in the event of the vehicle colliding with an obstacle . This results in an increased risk of injury to the respective vehicle occupant.

The object of the invention is therefore to propose a method for activating a vehicle occupant restraint system that can provide adequate protection for the vehicle occupant in the event of an impact, regardless of a vehicle occupant's position within the vehicle.

This object is achieved with a method for activating a vehicle occupant restraint system with the combination of features of claim 1. A vehicle occupant restraint system which is designed in particular to carry out this method is the subject of the independent claim.

Advantageous configurations of the invention are the subject matter of the dependent claims.

• - Erkennen, dass ein Aufprall mit einer Wahrscheinlichkeit von >90 % bevorsteht, wobei ein Aufprallzeitpunkt vorausberechnet wird;
• - Erfassen von Insassenparametern, wobei in Bezug auf wenigstens einen von einem Fahrzeuginsassen besetzten Fahrzeugsitz ein Sitzwinkel α zwischen einer Sitzfläche und einer Lehnenfläche des Fahrzeugsitzes erfasst wird;
• - Erkennen, dass der Sitzwinkel α größer ist als ein fahrzeugspezifischer Standardsitzwinkel α_s = [105° - 115°];
• - Verringern des Sitzwinkels α;

wobei der Sitzwinkel α innerhalb einer Zeitspanne von frühestens 1000 ms vor dem berechneten Aufprallzeitpunkt verringert wird.A method for activating a vehicle occupant restraint system includes the following steps:

• - Recognize that a collision is imminent with a probability of >90%, with a collision time being calculated in advance;
• - detecting occupant parameters, with respect to at least one vehicle seat occupied by a vehicle occupant, a seat angle α between a seat surface and a backrest surface of the vehicle seat being detected;
• - Detect that the seat angle α is greater than a vehicle-specific standard seat angle α _s = [105 ° - 115 °];
• - Decreasing the seat angle α;

where the seat angle α is reduced within a period of no earlier than 1000 ms before the calculated time of impact.

So-called crash monitoring systems make it possible to recognize when a vehicle can no longer be prevented from colliding with an obstacle, for example a collision with another road user, even in the case of autonomously controlled vehicles. At the same time, crash monitoring systems make it possible to calculate when the vehicle will impact the obstacle, i.e. it is possible to calculate the time of impact in advance.

Autonomous vehicles can mostly recognize in sufficient time in advance that there is a risk of a collision through their sensors and communication devices, which communicate with other road users in the vicinity of the autonomous vehicle under consideration or with a backend. As a rule, the autonomous vehicle is able to prevent such a collision, for example by braking in good time or by appropriate evasive maneuvers. Despite these possibilities, it will not be 100% possible to prevent all vehicle collisions, even with autonomous driving. It is therefore important to take appropriate measures to protect the occupants of the vehicle in question as best as possible.

On the other hand, especially with autonomous driving, the vehicle occupants should be disturbed as little as possible by such protective measures. For example, if a vehicle occupant sleeps in a suitably positioned vehicle seat, the vehicle occupant may be very uncomfortable if a vehicle occupant restraint system is activated in all possible potential collision situations.

Therefore, it is first important to recognize when activation of the vehicle occupant restraint system is necessary at all, whereby this is only necessary when a collision is imminent with a probability of more than 90% and is therefore most likely unavoidable. Depending on the performance of the sensors of the vehicle under consideration, it is also possible to recognize that the impact is imminent with a higher probability of up to 99%, in order to be sure that the vehicle occupant restraint system is only activated when absolutely necessary. It is particularly important here that the vehicle occupant restraint system is not activated if the minimum probability of an unavoidable collision has not been reached.

If it has now been recognized that a collision is imminent with a probability of >90%, occupant parameters are recorded by at least one vehicle occupant in order to activate the vehicle occupant restraint system based on these recorded vehicle occupant parameters.

A particularly important vehicle occupant parameter is the seat angle α between a seat surface and a backrest surface of the vehicle seat on which the vehicle occupant is sitting. If the seat angle α is particularly large, it can be concluded that the vehicle occupant is in a lying position and is, for example, completely at rest. However, this is also a position where the vehicle occupant is particularly vulnerable, as standard seat belts cannot adequately prevent the vehicle occupant from being thrown forward in the event of a crash. It is therefore particularly important that the at least one vehicle occupant is brought into an optimal seat angle α.

The optimal seat angle α _opt , to which the elements of a vehicle occupant restraint system, such as the seat belts, are usually optimized, is a vehicle-specific standard angle α _s that is ideal for driving the vehicle and therefore for homologation of the vehicle with regard to crash safety as a standard angle α _s is predetermined. The standard angle α _s is therefore regulated by legal requirements for the approval of each vehicle. In general, these vehicle-specific standard angles α _s are in an interval of [105°-115°] between the seat surface and the backrest surface of the vehicle seat. This means that the optimum seat angle α _opt or the standard angle α _s is between 15° and 25° beyond a 90° angle between the seat surface and the backrest surface.

If it is now recognized that the seat angle α is greater than this optimal, vehicle-specific standard seat angle α _s =[105°-115°], the vehicle occupant restraint system is activated in such a way that this seat angle α is reduced.

In order to enable the greatest possible comfort for the vehicle occupant, the seat angle α is only reduced within a period of no earlier than 1000 ms before the calculated time of impact.

Depending on the possible adjustment speed of the elements of the vehicle occupant restraint system, it is also possible to define the period of time before the calculated impact time, in which an adjustment of elements of the vehicle occupant restraint system takes place, to be less than 1000 ms and, for example, only in an interval between 200 ms and 1000 ms to activate the vehicle occupant restraint system at the calculated time of impact. In principle, however, it is advantageous to provide a buffer period of around 50 ms as the interval between the end of the vehicle seat adjustment and the time of the impact of the vehicle, so that a pre-acceleration of the vehicle occupant due to the vehicle seat being set up does not have a negative effect on the protective effect of the vehicle occupant restraint system.

If the period of time before the calculated impact time, when the vehicle occupant restraint system may be activated at the earliest, is set to 1000 ms, this contributes to the comfort of the vehicle occupant, but also helps to prevent the vehicle occupant restraint system from being activated incorrectly, for example if the sensors are incorrectly detected incorrectly detects an impact.

The seat angle α is preferably reduced to α=α _s .

If the seat angle α=α _s cannot be achieved within a predefined tolerance interval of [±5°-±15°], in particular within a predefined tolerance value of ±10°, within the time available up to the time of impact, an advantageous Configuration of a seat belt adjusted. In particular, the belt force level is reduced as a function of the seat angle α that can be reached within the available time span up to the time of impact.

This can be the case, for example, when the vehicle occupant is completely lying down, as a result of which the time available is no longer sufficient to reduce the seat angle α to the extent that α _s can be achieved. In this case, in which the seat angle adjustment is not completely successful or is not possible, the belt force level is preferably adjusted. In this way, the belt force level is advantageously reduced, for example by downshifting to a lower level of an adaptive belt force limiter if the backrest surface or torso angle of the vehicle occupant deviates from the standard angle α _s by more than 10°-15°. This advantageously means that it is easier for the vehicle occupant to rotate forward with the upper body, ie to stand up, and thus to make the best possible use of the space available for deceleration.

In relation to the at least one vehicle occupant, a distance d between a zero position of the vehicle seat on which the vehicle occupant is sitting and the current position of the vehicle seat is preferably detected, with the distance d being reduced if it is recognized that the distance d is greater than 30 mm, whereby the distance d is reduced within a period of at least 1000 ms before the calculated impact time.

The distance d from the zero position is direction-independent, so that a distance of d > 30 mm can mean in the direction of travel of the vehicle, but also against the direction of travel of the vehicle.

The zero position is a predefined position of the vehicle seat, which is defined using the arm and leg lengths of a standardized vehicle occupant. The zero position is thus the position with the optimum distance from a steering wheel in which at least one triggered airbag sack is usually arranged as an element of a vehicle occupant restraint system. If the vehicle seat is not in this optimal zero position, in which the airbag sack can develop its optimal effect in the event of an impact, but has been shifted out of this zero position, it is advantageous if the vehicle occupant restraint system is activated in such a way that the vehicle seat moves in the direction of the zero position is shifted. Accordingly, the distance d of the vehicle seat is reduced towards the zero position. Here, too, attention is paid to activating the displacement of the vehicle seat no earlier than 1000 ms before the calculated time of impact, in order to provide the vehicle occupant with the greatest possible comfort and to prevent erroneous reactions to erroneous detections.

The distance d is advantageously reduced to d=0 mm, with at least one airbag sack being deployed in the event of an impact.

This at least one airbag sack is advantageously arranged in a steering wheel inside the vehicle, so that the vehicle occupant is caught by the triggered and thus inflated airbag sack when the vehicle collides with an obstacle before the vehicle occupant hits components of the vehicle, for example the steering wheel.

A sum of a volume expansion of all airbag bags that are deployed is advantageously adjusted as a function of the distance d that can be reached within the available time span up to the time of impact.

In a particularly advantageous embodiment, a further airbag sack is deployed in addition to the at least one airbag sack in the event of an impact if a distance of d<100 mm cannot be reached within the available time span up to the time of impact. In this case, the further airbag sack is preferably arranged in the deployed state between the deployed airbag sack and the vehicle seat.

In the event that the vehicle seat with the vehicle occupant sitting on it has moved too far backwards from the zero position during the impact, a standard airbag sack is not sufficient to optimally absorb the vehicle occupant in the event of an impact. Therefore, advantageously in such a case, the Volu expansion by providing a further airbag sack, which is, for example, in fluid connection with the standard airbag sack, increased in order to bridge the excessive distance.

Accordingly, the additional airbag sack should be ignited as soon as the distance between the vehicle occupant and a steering wheel (or an instrument panel for the passenger) exceeds a certain level. This dimension depends on the design (volume) of the additional airbag sack, which is why it is possible to bridge a distance of 100 - 250 mm, depending on the volume of the additional airbag sack.

The critical distance d, at which it makes sense to ignite the additional airbag sack, is advantageously measured or predicted after the vehicle seat has been adjusted.

Airbag systems are already known in which standard airbags have additional adaptive outflow openings in order to inflate them in a way that is specially adapted to the impact situation. In the event that the additional airbag sack is triggered, this adaptive outflow opening is advantageously closed.

The method accordingly analyzes the situation inside the vehicle via the occupant parameters and decides which elements of the vehicle occupant restraint system must be activated and how, both before the impact occurs and afterwards, in order to protect the vehicle occupant in the best possible way.

According to the method it is therefore possible to provide an adaptive vehicle seat that is activated before the impact and corresponding restraint systems, such as airbag bags and safety belts, that work in an ideal manner during and after the impact.

A combination of such an adaptive vehicle seat with the appropriately activated restraint systems is also possible.

Further occupant parameters are preferably recorded, which relate in particular to the size and weight of the vehicle occupant. This makes it possible to further adapt the adjustment of the seat angle α and the distance d to the vehicle occupant. For example, a vehicle seat on which a very tall and heavy man (e.g. >1.9 m and more than 100 kg) is seated must be adjusted differently in terms of seat angle α and distance d than a vehicle seat on which a very small and light person is sitting Woman (1.5 m and 45 kg) seated.

Depending on the size of the vehicle occupant, which is preferably detected by appropriate sensors, the vehicle seat is advantageously shifted into a position that is optimal for this vehicle occupant. For example, for an average-sized man and a tall man, these would be their specific standard positions. However, vehicle occupants smaller than the average man would, for example, be driven backwards with the vehicle seat from the standard position in which they would be able to drive the vehicle in order to have an optimal distance d to the airbag sack.

In addition, it is also optionally possible to record the speed and other dynamic parameters of the vehicle itself in order to include this in the activation parameterization of the vehicle occupant restraint system.

A vehicle occupant restraint system has a safety belt, which is in operative connection with a belt force limiter for adjusting a belt tension of the safety belt, and at least one airbag sack, which is designed to be triggered in the event of an impact. The vehicle occupant restraint system also has a seat angle adjustment device for adjusting a seat angle α between a seat surface and a backrest surface of the vehicle seat and a control device with a sensor element for detecting that the seat angle α is greater than a vehicle-specific standard seat angle α _s = [105° - 115°]. . The control device is designed to activate the seat angle adjustment device within a time period of no earlier than 1000 ms before a calculated impact time in order to reduce the seat angle α.

The control device is preferably designed to switch the belt force limiter to a lower level to reduce a belt force level of the seat belt if the seat angle α = α _s is not within a predefined tolerance interval of [± 5° - ± 15°], in particular within a predefined tolerance value of ±10°.

The belt force limiter is therefore adjusted depending on the seat angle (lying down = low belt force level, upright = high belt force level

A vehicle seat displacement device is advantageously also provided, with the control device having a further sensor element for detecting that a distance d between a zero position of the vehicle seat on which the vehicle occupant is sitting and the current position of the vehicle seat is greater than an acceptable tolerance of 30 mm, wherein the control device is designed to activate the vehicle seat displacement device within a time period of no earlier than 1000 ms before the calculated time of impact in order to reduce the distance d.

The vehicle occupant restraint system preferably has an additional airbag sack which, in the deployed state, is designed to be arranged between the deployed airbag sack and the vehicle seat, the control device being designed to activate the additional airbag sack for deployment in the event of an impact if within the available A distance of d < 100 mm cannot be reached before the point of impact.

• 1 eine schematische Seitenansicht auf einen Fahrzeuginsassen in einem Fahrzeug mit einem Fahrzeuginsassenrückhaltesystem, das ein Airbagsystem sowie Sicherheitsgurte aufweist;
• 2 eine weitere Seitenansicht auf den Fahrzeuginsassen aus 1 nach einem Aufprall des Fahrzeuges, wobei das Airbagsystem zwei Airbagsäcke ausgelöst hat;
• 3 ein schematisches Flussdiagramm mit Schritten eines Verfahrens zum Aktivieren des Fahrzeuginsassenrückhaltesystem aus 1;
• 4 ein schematisches Flussdiagramm mit weiteren Schritten des Verfahrens aus 3;
• 5 ein schematisches Flussdiagramm mit weiteren Schritten des Verfahrens aus 3 und 4; und
• 6 ein schematisches Flussdiagramm mit weiteren Schritten des Verfahrens gemäß 5.

Advantageous configurations of the invention are explained in more detail below with reference to the accompanying drawings. It shows:

• 1 a schematic side view of a vehicle occupant in a vehicle with a vehicle occupant restraint system having an airbag system and seat belts;
• 2 Another side view of the vehicle occupant 1 after a vehicle collision in which the airbag system has triggered two airbag bags;
• 3 1 shows a schematic flow diagram with steps of a method for activating the vehicle occupant restraint system 1 ;
• 4 a schematic flowchart with further steps of the method 3 ;
• 5 a schematic flowchart with further steps of the method 3 and 4 ; and
• 6 a schematic flow chart with further steps of the method according to 5 .

1 shows a schematic side view of a vehicle occupant 10 in a vehicle 12 who occupies a vehicle seat 14 . The vehicle seat 14 is positioned in the vehicle 12 such that the vehicle occupant 10 can rest in a relaxed manner while the vehicle 12 drives autonomously, for example, and does not require any intervention by the vehicle occupant 10 as the driver. In this relaxed position for the vehicle occupant 10, the vehicle seat 14 has a seat angle α of approximately 120° between a seat surface 16 and a backrest surface 18. This means that the seat angle is α in 1 significantly larger than a standard seat angle α _s or optimal seat angle α _opt of 105°, for example.

Next is in 1 the vehicle seat 14 is pushed far enough away from a steering wheel 20 of the vehicle 12 that the driver has plenty of legroom, but at the same time can no longer operate the steering wheel 20 with his arms. The vehicle seat 14 is thus shifted backwards by a distance d from a zero position d ₀ . The zero position d ₀ is the standard position of the vehicle seat 14 in which the vehicle occupant 10 as the driver can optimally operate the vehicle 12 when driving the vehicle.

The vehicle 12 has several elements of a vehicle occupant restraint system 22, in particular an airbag system 24 in the steering wheel 20 and a seat belt 26.

If the vehicle seat 14 is in a standard position, i.e. on the one hand in the zero position d ₀ and on the other hand in the standard seat angle α _s = 105°, then the elements of the vehicle occupant restraint system 22, namely the airbag system 24 and the safety belt 26, work optimally in the event of a collision of the vehicle 12 .

However, if the vehicle seat 14 is located, as in 1 shown, not in the standard position, but is in particular in the lying position and moved backwards away from the steering wheel 20, neither the seat belt 26 nor the airbag system 24 can develop their optimum effect and effectively protect the vehicle occupant 10 in the event of an impact.

It is therefore now proposed that the vehicle seat 14 be brought as close as possible to the standard position if an impact of the vehicle 12 cannot be avoided, in order to be able to better protect the vehicle occupant 10 .

For this purpose, the vehicle occupant restraint system 22 has a control device 28 with a plurality of sensor elements 30, 32 which are designed to detect the positioning of the vehicle seat 14. The sensor element 30 can detect the seat angle α at which the vehicle seat 14 is set and in particular whether this seat angle α is greater than 105°. The sensor element 32 is designed to detect whether the vehicle seat 14 is arranged in the zero position d ₀ or is at a distance d from this zero position d ₀ . In particular, the sensor element 32 detects whether a distance d between the zero position d ₀ and the current position of the vehicle seat 14 is greater than 30 mm.

If a crash monitoring system (not shown) assigned to the vehicle 12 now recognizes that a collision of the vehicle 12 can no longer be avoided, i.e. that there is a >90% probability that a collision will occur, a collision time t _A calculated.

A seat angle adjustment device 34 is attached to the vehicle seat 14 and acts integrally as a vehicle seat displacement device 36 and which can be activated by the control device 28 .

If the vehicle seat 14 is in an unfavorable position, so that the vehicle occupant restraint system 22 cannot work optimally, the control device 28 activates the seat angle adjustment device 34 at the earliest 1000 ms before the calculated impact time t _A in order to reduce the seat angle α as far as possible to α = α _opt .

The control device 28 preferably also activates the vehicle seat displacement device 36 in order to reduce the distance d, so that the vehicle seat 14 is in the zero position d ₀ at the impact time t _A if possible.

Both the adjustment of the seat angle α and the displacement of the vehicle seat 14 are activated at the earliest 1000 ms before the calculated impact time t _A in order not to disturb the vehicle occupant 10 on the one hand, but also to prevent the collision situation from being unnecessarily prepared due to incorrect detection.

Depending on which position the vehicle occupant 10 has assumed on his vehicle seat 14, it is possible that the control device 28 is no longer able to move the vehicle seat 14 to the optimum position, i.e. to the standard angle, via the seat angle adjustment device 34 or the vehicle seat displacement device 36 α _s = 105° and bring it into the zero position d ₀ .

The control device 28 is therefore also designed to switch a belt force limiter 38, which is provided for setting a belt force level of the seat belt 26, to a lower level. If the seat angle α = 105° cannot be achieved by adjusting the seat angle α via the seat angle adjustment device 34 within the available time period up to the time of impact t _A , the control device 28 reduces the belt force level of the seat belt 26 via the belt force limiter 38 the belt force level is reduced as a function of the seat angle α that can be reached within the time available up to the time of impact t _A . That is, if a seat angle α=108° can be achieved, the belt force level of the seat belt 26 is reduced only minimally, while the belt force level of the seat belt 26 is greatly reduced if it is only possible to achieve a seat angle α of 120°.

Furthermore, the control device 28 is also designed to selectively activate the airbag system 24, i.e. to activate at least one or more airbag bags 40.

In principle, at least one airbag bag 40, which is usually arranged in the steering wheel 20, is triggered when the vehicle 12 collides with an obstacle, unfolds and arranges itself between the vehicle occupant 10 and the steering wheel 20 due to its volume expansion, so that the vehicle occupant 10 is Airbag bag 40 is caught on impact.

If the sensor element 32 now detects that the distance d is so great that the zero position d ₀ cannot be reached by moving the vehicle seat 14 within the time available up to the time of impact t _A , the control device 28 controls the airbag system 24 in such a way that that the Volumetric expansion of all available in the airbag system 24 airbag sacks 40 is adapted to the distance d. This can, as in 2 shown, by another airbag sack 40 which is in fluid communication with the usual airbag sack 40 and expands additionally when deployed. This increases the volume expansion and the distance d can be bridged.

In 3 1 is a schematic flow diagram of steps of a method for activating the vehicle occupant restraint system 22. FIG. In a first step, it is recognized that an impact is imminent with a probability of >90% and the impact time t _A is calculated at the same time. In the next step, occupant parameters are then recorded, in particular the seat angle α between the seat surface 16 and the backrest surface 18. In the next step, it is then recognized whether the seat angle α is greater than the standard seat angle α _s of, for example, 105°. If this is the case, there is first a wait until only a short, predefined period of time tt is available until the time of impact t _A , in particular tt is <1000 ms. Only then is the seat angle α reduced in a last step.

4 shows a further schematic flowchart with further steps of the reference to 3 described method, wherein after recognizing that the seat angle α is greater than the standard seat angle α _s , it is additionally recognized in a further step that a seat angle α _f achievable by adjusting the backrest surface 18 is also greater than the standard seat angle α _s , wherein a tolerance of 10°, for example, is taken into account. In a further step, the belt force level of the seat belt 26 is correspondingly reduced via the control device 28 .

5 shows a further schematic flowchart with steps of the method for activating the vehicle occupant restraint system 22, in which in addition to in 3 and 4 shown adjusting the seat angle α further steps are performed.

Here, too, it is recognized in the first step that an impact is imminent with a probability of >90%, with the impact time t _A being calculated at the same time. In the next step, in addition to the seat angle α, the distance d is recorded as a further occupant parameter, and in the next step it is recognized whether the distance d is greater than 30 mm. If this is the case, there is also a wait until the period of time tt before the calculated impact time t _A has been reached, which is a maximum of 1000 ms, in order to then reduce the distance d via the vehicle seat displacement device 36 .

6 shows a further schematic flow chart with further steps of the method according to FIG 5 , it also being initially recognized that the distance of the vehicle seat 14 from the zero position d ₀ is greater than 200 mm, and then it is also recognized that a distance d _f that can be achieved by moving the vehicle seat 14 also does not yet correspond to the zero position d ₀ , and even deviates from it by more than 100 mm, so that in the last step the further airbag sack 40 is triggered in addition to the airbag sack 40 which triggers by default.

The effectiveness of the method or vehicle occupant restraint system 22 described above is presented below using simulation data. In the following tables, a value for an average degree of injury to the vehicle occupant 10 is shown for different positions of the vehicle seat 14 with respect to the distance d and for different seat angles α.

The average degree of injury to the vehicle occupant 10 is calculated from an average percentage value from four different body regions of the vehicle occupant 10 that can be affected by an impact. These are the head, neck, chest and leg areas. Percentage values are determined for each of these four areas to what extent the respective area is exposed to acceleration forces, compression forces, tensile forces and bending forces.

These percentage values are averaged over all four areas to give the average values shown in the tables.

1. 1. Simulationsergebnisse für ein Fahrzeuginsassenrückhaltesystem 22 ohne Sitzverstellung vor dem Aufprall:

α = 135° 52,5 45,2 51,0 31,5 α = α_opt = 105° 45,4 37,2 45,4 31,2 d = -100 mm d = d₀ d = 100 mm d = 200 mm

• 2. Simulationsergebnisse für ein Fahrzeuginsassenrückhaltesystem 22 mit Sitzverschiebung und Sitzwinkelverstellung vor dem Aufprall:

α = 135° 39,5 39,3 37,4 34,8 α = α_opt = 105° 44,6 37,2 36,5 33,5 d = -100 mm d = d₀ d = 100 mm d = 200 mm

• 3. Simulationsergebnisse für ein Fahrzeuginsassenrückhaltesystem 22 mit Sitzwinkelverstellung vor dem Aufprall:

α = 135° 41,6 39,3 42,6 35,7 α = α_opt = 105° 45,4 37,2 45,4 31,2 d = -100 mm d = d₀ d = 100 mm d = 200 mm

• 4. Simulationsergebnisse für ein Fahrzeuginsassenrückhaltesystem 22 mit Sitzwinkelverstellung vor dem Aufprall und zusätzlich sich öffnendem Airbagsack 40 beim Aufprall:

α = 135° 41,6 39,3 42,6 27,5 α = α_opt = 105° 45,4 37,2 45,4 26,9 d = -100 mm d = d₀ d = 100 mm d = 200 mm The tables below show the determined average values of the stresses to be endured for the body for different distances d and seat angle α for the different systems. If the average value is below 40%, this is the optimal combination of protective measures from the point of view of vehicle occupant protection.

1. 1. Simulation results for a vehicle occupant restraint system 22 with no pre-impact seat adjustment:

α = 135° 52.5 45.2 51.0 31.5 α = α _opt = 105° 45.4 37.2 45.4 31.2 d = -100mm d = _d0 d = 100mm d = 200mm

• 2. Simulation results for a vehicle occupant restraint system 22 with pre-impact seat translation and recline:

α = 135° 39.5 39.3 37.4 34.8 α = α _opt = 105° 44.6 37.2 36.5 33.5 d = -100mm d = _d0 d = 100mm d = 200mm

• 3. Simulation results for a vehicle occupant restraint system 22 with pre-impact seat angle adjustment:

α = 135° 41.6 39.3 42.6 35.7 α = α _opt = 105° 45.4 37.2 45.4 31.2 d = -100mm d = _d0 d = 100mm d = 200mm

• 4. Simulation results for a vehicle occupant restraint system 22 with a seat angle adjustment prior to the impact and an airbag bag 40 that also opens on impact:

α = 135° 41.6 39.3 42.6 27.5 α = α _opt = 105° 45.4 37.2 45.4 26.9 d = -100mm d = _d0 d = 100mm d = 200mm

It can be seen that actions taken prior to the vehicle 12 impacting an obstacle result in the best simulated result in terms of the degree of injury to the vehicle occupant 10 .

If, in particular, injuries to the lumbar vertebrae are considered (not taken into account in the tables presented above), the simulations have shown that only measures taken before the vehicle 12 crashes help to avoid injuries here. In particular, forces acting on the lumbar spine are particularly high when the vehicle occupant 10 is in a reclining position, ie the seat angle α is particularly large. It is therefore particularly important to reduce the seat angle α and thus raise the backrest surface 18 before the vehicle 12 hits the obstacle.

Reference List

10

vehicle occupant

12

vehicle

14

vehicle seat

16

seat

18

backrest surface

20

steering wheel

22

vehicle occupant restraint system

24

airbag system

26

seat belt

28

control device

30

sensor element (seat angle)

32

sensor element (distance)

34

seat angle adjustment device

36

vehicle seat slide device

38

belt force limiter

40

airbag bag

a

seat angle

αf

achievable seat angle

αopt

optimal seat angle

αs

standard seat angle

i.e

Distance

d0

zero position

df

achievable distance

ta

time of impact

tf

Period of time

Claims (9)

Method for activating a vehicle occupant restraint system (22), comprising the steps of: - recognizing that a collision is imminent with a probability of >90%, with a collision time (t _A ) being calculated in advance; - detecting occupant parameters, with respect to at least one of a vehicle occupant (10) occupied vehicle seat (14) a seat angle (α) between a seat surface (16) and a backrest surface (18) of the vehicle seat (14) is detected; - Detect that the seat angle (α) is greater than a vehicle-specific standard seat angle α _s = [105 ° - 115 °]; - Decreasing the seat angle (α); wherein the seat angle (α) is reduced within a period of time (t _f ) no earlier than 1000 ms before the calculated impact time (t _A ). procedure after claim 1 , characterized in that the seat angle (α) is reduced to α = α _s , in particular a belt force level of a safety belt (26) being reduced if the seat angle within the available time span (tf) up to the time of impact (t _A ). α = α _s cannot be achieved within a predefined tolerance interval of [± 5° - ±15°], in particular within a predefined tolerance value of ±10°, with the belt force level in particular depending on the available time period (tf ) until the moment of impact (t _A ) achievable seat angle (α) is reduced. Procedure according to one of Claims 1 or 2 , characterized in that with respect to the at least one vehicle occupant (10), a distance (d) between a zero position (d ₀ ) of the vehicle seat (14) on which the vehicle occupant (10) is sitting and the current position of the vehicle seat (14 ) is detected, the distance (d) being reduced if it is detected that the distance (d) is greater than 30 mm, the distance (d) being detected within a time period (tf) of no earlier than 1000 ms before the calculated impact time ( t _A ) is reduced. procedure after claim 3 , characterized in that the distance (d) is reduced to d = 0 mm, at least one airbag sack (40) being triggered upon impact, with in particular a sum of a volume expansion of all the airbag sacks (40) being triggered depending on the available Standing period of time (tf) until the time of impact (t _A ) achievable distance (d) is adjusted. procedure after claim 4 , characterized in that in the event of an impact, in addition to the at least one airbag sack (40), a further airbag sack (40) is triggered if within the are available a distance of d <100 mm cannot be reached during the period of time (tf) up to the time of impact (t _A ), with the further airbag sack (40) being arranged in the deployed state between the deployed airbag sack (40) and the vehicle seat (14). Vehicle occupant restraint system (22), comprising: - a safety belt (26) which is operatively connected to a belt force limiter (38) for adjusting a belt tension of the safety belt (26); - At least one airbag sack (40) which is designed to be triggered in the event of an impact; - A seat angle adjustment device (34) for adjusting a seat angle (α) between a seat surface (16) and a backrest surface (18) of a vehicle seat (14); and - a control device (28) with a sensor element (30) for detecting that the seat angle (α) is greater than a vehicle-specific standard seat angle α _s = [105° - 115°], the control device (28) being designed for this purpose, to activate the seat angle adjustment device (34) within a period of time (tf) of no earlier than 1000 ms before a calculated impact time (t _A ) to reduce the seat angle (α). Vehicle occupant restraint system (22) after claim 6 , characterized in that the control device (28) is designed to switch the belt force limiter (38) to reduce a belt force level of the seat belt (26) to a lower level if within the available time span (tf) up to the time of impact (t _A ) the seat angle α=α _s cannot be achieved within a predefined tolerance interval of [±5°-±15°], in particular within a predefined tolerance value of ±10°. Vehicle occupant restraint system (22) according to one of Claims 6 or 7 , characterized by a vehicle seat displacement device (36), wherein the control device (28) has a further sensor element (32) for detecting that a distance (d) between a zero position (d ₀ ) of the vehicle seat (14) on which the vehicle occupant (10 ) is seated and the current position of the vehicle seat (14) is greater than 30 mm, the control device (28) being designed to move the vehicle seat displacement device (36) within a time period (tf) of at most 1000 ms before the calculated impact time (t _A ) to decrease the distance (d). Vehicle occupant restraint system (22) after claim 8 , further comprising a further airbag sack (40) which, in the deployed state, is designed to be arranged between the deployed airbag sack (40) and the vehicle seat (14), the control device (28) being designed to activate the further airbag sack ( 40) to be activated for triggering if a distance of d < 100 mm cannot be reached within the available time span (tf) up to the time of impact (t _A ).

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