Method for operating a seat belt system

Abstract

The invention relates to a method for operating a seat belt system (10) for an occupant (12) in a motor vehicle (14), the seat belt system comprising a seat belt for restraining the occupant (12), a seat belt buckle (26) and a sensor (28) for detecting the extension of the seat belt. The method starts to react when the extension of the seat belt exceeds a threshold value, the threshold value taking into account the minimum seat belt extension after the seat belt buckle (26) is closed, wherein the threshold value takes into account the minimum seat belt extension within 30 seconds after the seat belt buckle (26) is closed, and the threshold value=minimum seat belt extension+permitted distance, wherein the permissible distance depends on the current speed of the motor vehicle (14) in such a way that the permissible distance decreases as the speed increases.

Description

Technical Field

[0001] The invention relates to a method for operating a seat belt system for an occupant in a vehicle. Background Art

[0002] Seat belt systems for vehicles are known. The effect that a seat belt system has on a belted occupant and therefore the protection provided by the seat belt depends decisively on the (sitting) posture of the belted occupant. Studies in accident investigations have found that a not insignificant portion of the occupants, however, adopt a sitting posture in the vehicle that deviates from the optimal sitting posture for reasons of comfort. That is, the occupants are positioned in relation to the safety devices (e.g. seat belts and airbags) in such a way that in the case of a restraint the seat belt system cannot provide its full protective effect. This can lead to an increased load on the occupant in the case of a restraint and an increased risk of injury. Summary of the invention

[0003] The object of the present invention is to provide a method for operating a seat belt system which ensures an improved protective effect.

[0004] In order to achieve the object, a method for operating a seat belt system for an occupant in a motor vehicle is proposed. The seat belt system comprises a seat belt for restraining the occupant, a belt buckle for closing the seat belt system and a sensor for detecting the extension of the seat belt. Within the scope of the method, a reaction is initiated when the extension of the seat belt exceeds a threshold value. In this case, the threshold value takes into account the minimum extension of the seat belt after the belt buckle is closed, wherein the threshold value takes into account the minimum extension of the seat belt within 30 seconds, preferably within 20 seconds, in particular within 10 seconds after the belt buckle is closed, and the threshold value=minimum extension of the seat belt+permitted distance, wherein the permissible distance depends on the current speed of the motor vehicle in such a way that the permissible distance decreases as the speed increases. In the sense of the invention, the extension of the seat belt is the distance that the seat belt is pulled out or unwound from the seat belt reel compared to a reference value. The reference value can be, for example, the position of the seat belt, which the seat belt has when it is in a positionally stable position, in which the seat belt is provided to the occupant in the vehicle for extension. The seat belt system is adapted to the occupant or adjusted by taking into account the minimum seat belt extension after the seat belt buckle is closed, that is, the body shape or dimensions of the occupant are taken into account in the threshold value. In this way, a threshold value that is individually adapted to the occupant and thus an improved protective effect can be provided.

[0005] If the belted occupant is in an optimal sitting position, for example sitting upright with his back against the backrest of his seat, the belt extension is usually minimal. Any change in the occupant's posture relative to the optimal sitting position, for example because the occupant leans forward or because the occupant has pulled the belt further out so that the belt does not rest tightly against his body, leads to a higher belt extension. In the proposed method, an excessive incorrect posture of the occupant or an incorrect positioning of the belt leads to a belt extension exceeding a threshold value and triggering a reaction. With the aid of this reaction, the incorrect posture or incorrect positioning can be corrected. In this way, the occupant's posture relative to the belt system is improved and the protective effect of the belt system is thus increased in the case of restraint.

[0006] According to one embodiment, the threshold value takes into account the minimum belt extension within 30 seconds, preferably within 20 seconds, and in particular within 10 seconds after the belt buckle is closed. The idea is that after fastening the belt, i.e. after the belt buckle is closed, the occupant assumes the optimal sitting position at least briefly before the occupant later deviates from the optimal sitting position, for example due to comfort or fatigue. By taking into account the minimum belt extension within the time window shortly after fastening the belt, it is ensured that the threshold value is at least as close as possible to the optimal threshold value, which corresponds to the threshold value when the optimal sitting position is taken into account.

[0007] Since it is not possible to ensure that the occupant assumes the optimal sitting position within a certain time window, the threshold value can take into account the minimum belt extension after the belt buckle is closed continuously or at regular intervals (e.g. at a frequency of 100 Hz). Since an improved sitting position usually requires a reduction in belt extension after the belt is fastened, the threshold value can be updated in this way throughout the time the occupant is fastened and thus improved. This improves the accuracy of when the reaction is triggered.

[0008] Furthermore, the threshold value can take into account the sitting position of the occupant, in particular the position of the upper body, by means of sensors. For this purpose, for example, a camera or a (pressure) sensor can be provided in the backrest. In this way, the threshold value and thus the protective effect of the seat belt system can be improved, for example by reducing the threshold value accordingly in the case of a forward-bending position of the occupant, so that the (wrong) position can be corrected by reaction before the occupant leans back for the first time.

[0009] It can be provided that the threshold value takes into account the seat position of the passenger seat, the seat position of a seat arranged in the vehicle in front of the passenger seat and / or the position of a steering wheel arranged in the vehicle in front of the passenger seat. In the sense of the invention, "in front of the vehicle" means being arranged closer to the front of the vehicle, in particular wherein the front points in the main direction of travel of the vehicle. If the vehicle does not have a defined front or the line of sight of the passenger does not coincide with the direction of travel, "in front of the vehicle" can also mean "in front of the passenger in the line of sight direction". Thus, the relative position of the passenger with respect to his surroundings can be taken into account within the threshold value, thereby, for example, ensuring that the passenger does not collide with the steering wheel or the front seat when restrained.

[0010] In one embodiment, the threshold value can take into account the position of an airbag or the positions of multiple airbags. This ensures that a reaction is always triggered when the position of the occupant relative to the airbag leads to a reduction in the protective effect.

[0011] In another embodiment, the threshold value can take into account the position of an airbag which is arranged opposite the occupant in the direction of travel. This ensures that a reaction is always triggered when the occupant is too close to the airbag which is primarily provided for the occupant to collide in the restraint situation. Thus, for example, it can be prevented that the airbag already comes into contact with the occupant before full deployment, rather than the occupant sinking into the already inflated airbag.

[0012] The reaction triggered when a threshold value is exceeded can include the sending of an acoustic and / or optical signal by means of an output device in order to transmit information to the occupant. For example, a loudspeaker or a display can be provided as an output device, which is already present in the vehicle and can have other functions. In this way, the occupant can be informed that his sitting position deviates too far from the optimal sitting position so that the occupant can correct his sitting position.

[0013] Furthermore, the reaction can include activating the belt tensioner for tightening the belt, so that the restraining force of the belt is increased. Here, the restraining force is a traction force for pulling the belt in the direction of the belt reel. This means that the pressure exerted by the belt on the occupant increases, so that, for example, the occupant can be asked to adjust his sitting position with a small traction force. Alternatively, a higher traction force can be used to urge the occupant to change his posture, for example, in order to make a sleeping person stand up and move into a safe posture.

[0014] The restraining force of the seat belt can be increased by a fixed value, a value that increases continuously over time or a value that fluctuates over time. If the restraining force of the seat belt is increased by a value that fluctuates over time, a force pulse is introduced into the seat belt, which the occupant perceives as a pressure change. The intensity and course of the change in the restraining force can be used to transmit a request to the occupant to adjust his or her sitting position in different ways. For example, a request can be mandatory when a collision is imminent, for example when the vehicle is stationary. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further advantages and features are apparent from the following description in conjunction with the accompanying drawings, in which:

[0016] Figure 1 and Figure 2 A schematic diagram shows how a seat belt system for an occupant on a driver's seat of a motor vehicle is operated using the method according to the invention, and

[0017] Figure 3 and Figure 4 The schematic diagram shows how a seat belt system for occupants on the rear seats of a motor vehicle is operated using the method according to the invention. DETAILED DESCRIPTION

[0018] Figure 1 The seat belt system 10 is shown for an occupant 12 in a motor vehicle 14. The occupant 12 is seated in a driver's seat 16 of the motor vehicle 14. In front of the driver's seat 16 a steering wheel 18 of the motor vehicle 14 is arranged.

[0019] The seat belt system 10 includes a seat belt 20 having a seat belt tongue 22, a seat belt reel 24 partially wound with the seat belt 20 and exerting traction on the seat belt 20, and a seat belt buckle 26 that can be locked with the seat belt tongue 22. The seat belt 20 is used to restrain the occupant 12 in the driver seat 16 when the seat belt buckle 26 is closed. The seat belt buckle 26 is closed by inserting the seat belt tongue 22 into the seat belt buckle 26 and locking with the seat belt buckle.

[0020] Arranged on the belt reel 24 is a reel rotation sensor 28 , by means of which an axial rotation of the belt reel 24 and thus a belt extension of the belt webbing 20 is detected in a known manner.

[0021] The seat belt system 10 further includes a seat belt tensioner 30 which is provided for tensioning the seat belt 20 or winding the seat belt 20 onto the seat belt reel 24 .

[0022] The driver's seat 16 has a backrest 32 with a pressure sensor 34 which is designed to detect whether the occupant 12 is leaning against the backrest 32 .

[0023] Furthermore, the driver's seat 16 and the backrest 32 can be adjusted in a conventional manner and can be positioned in the motor vehicle 14. During the adjustment of the driver's seat 16, the execution of the method can be interrupted for the duration of the adjustment.

[0024] In order to protect the occupant 12 in the event of a collision, an airbag 36 is arranged in the steering wheel 18 , which airbag can be triggered in a known manner in the event of a collision.

[0025] The motor vehicle 14 comprises a display 38, by means of which information can be provided visually to the occupant 12. Additionally or alternatively, a loudspeaker can be provided in the motor vehicle 14, by means of which information can be provided acoustically to the occupant 12.

[0026] Furthermore, a camera 40 is provided in the motor vehicle 14 , which is provided to determine the body posture or sitting position of the occupant 12 .

[0027] The driver's seat 16 , the belt buckle 26 , the reel rotation sensor 28 , the belt tensioner 30 , the pressure sensor 34 , the airbag 36 , the display 38 and the camera 40 are connected to an onboard computer (not shown) of the motor vehicle 14 in a signal-transmitting manner.

[0028] The onboard computer is provided for controlling the above-described systems and for carrying out the following method for operating the seat belt system 10. In an alternative embodiment, a separate controller may be provided for carrying out the method for operating the seat belt system 10, which controller is connected at least to the seat belt buckle 26 and the reel rotation sensor 28 for signal transmission.

[0029] exist Figure 1 1 shows the occupant 12 in an optimal sitting position, which is characterized in that the occupant 12 is sitting in the driver's seat 16 in an upright position with his upper body 42 leaning against the backrest 32. In this position, the occupant 12 is ideally protected by the safety belt system 10.

[0030] exist Figure 2 1 shows the occupant 12 in a sitting position in which the occupant 12 is bent forward toward the steering wheel 18. Here, the upper body 42 of the occupant 12 is away from the backrest 32, which results in the safety belt 20 being more secure than in the optimal sitting position (see Figure 1 ) is pulled out further. In this sitting position, the protection of the occupant 12 by the safety belt system 10 is weakened.

[0031] A sitting position in which the protective effect of the seat belt system 10 is significantly reduced is referred to as a critical sitting position and is characterized by a seat belt extension greater than a certain threshold value.

[0032] In order to correct the critical sitting position of the occupant 12 and thus better protect the occupant 12, the on-board computer monitors the belt extension after the belt buckle 26 is closed. The closing of the belt buckle 26 informs the on-board computer that the occupant 12 is sitting in the driver's seat 16 and wearing the seat belt 20. For this purpose, the belt buckle 26 can include a sensor that informs the on-board computer of the closed state of the belt buckle 26.

[0033] After the seat belt buckle 26 is closed, the onboard computer determines the current seat belt extension at a frequency of 100 Hz. Alternatively, the frequency used by the onboard computer to determine the current seat belt extension can be arbitrary.

[0034] The onboard computer now determines a threshold value which describes the critical sitting position. The following formula applies for the threshold value:

[0035] Threshold = minimum belt extension + allowed distance.

[0036] The minimum belt extension is the minimum measured value of the belt extension since the belt buckle 26 was closed. This value is measured and updated over the entire duration of the belt buckle 26 being closed. Alternatively, this value can be measured and updated within a limited time window, in particular directly after the belt buckle 26 is closed. This time window is, for example, 10 seconds, 20 seconds or 30 seconds long.

[0037] The permissible distance specifies the length by which the safety belt 20 can be pulled out without the occupant 12 reaching a critical sitting position. This means that the permissible distance determines a "free space" that secures the occupant 12 and does not trigger a reaction in this "free space".

[0038] The permissible distance and thus the threshold value can depend on various parameters, such as for which seat in the vehicle the seat belt system 10 is provided and how other restraints, such as an airbag, are arranged relative to the seat. In this context, the position of the airbag 36, which is arranged in front of the occupant 12 in the direction of travel F, can be taken into account in particular.

[0039] Furthermore, the allowed distance may depend on what the seat position of the driver's seat 16 and / or the position of the steering wheel 18 is.

[0040] Furthermore, the posture or sitting position of the occupant 12 can be taken into account at a permissible distance using the camera 40 and / or the pressure sensor 34 .

[0041] In an alternative embodiment, the permissible distance can also depend on the current speed of motor vehicle 14 , for example in that the permissible distance decreases as the speed increases.

[0042] In the present case, the permissible distance is 250 mm. In an alternative embodiment, the permissible distance can have any desired value, which preferably at least partially takes into account the above-mentioned parameters.

[0043] If the current belt extension exceeds this threshold, for example because the occupant 12 leans forward too far (see Figure 2 ), the on-board computer starts to react in order to inform the occupant 12 of the critical sitting position and correct it if necessary.

[0044] The reaction consists in urging the occupant 12 to assume the optimal sitting position by means of a flashing symbol on the display 38 .

[0045] In addition, the belt tensioner 30 is activated, thereby gradually increasing the force applied to the occupant 12 by the belt 20. Here, the maximum force is limited so that the occupant 12 is not injured. Alternatively, the force can be increased by a fixed value, a step-by-step value or a fluctuating value.

[0046] In an alternative embodiment, a reaction can only be initiated if a threshold value is exceeded for a certain duration (e.g. 2 seconds). In this way, brief posture changes, as are common when driving, do not lead to a reaction, for example when the driver turns his head to look or when the front passenger bends forward to pick up something from the foot area.

[0047] Furthermore, different reactions can be initiated at different times. For example, after exceeding the threshold value, the occupant 12 can be visually informed via the display 38 . If the threshold value is not again undershot within 2 seconds, the onboard computer activates the belt tensioner 30 and thus increases the pressure of the belt 20 on the occupant 12 .

[0048] Furthermore, it can be provided that no reaction is triggered in certain driving situations, for example when reversing, in which the driver usually adopts a body position that allows him to have a better view, but in this case deviates greatly from the optimal sitting position. It can also be provided that no reaction is triggered when adjusting the driver's seat, in particular when moving it longitudinally and / or changing the inclination of the backrest.

[0049] In this way, the occupant 12 is informed when the occupant's sitting position is in a critical area and the protective effect of the seat belt system 10 is thereby reduced. The occupant 12 thus has the ability to correct his sitting position himself and thereby increase his safety.

[0050] Furthermore, the posture of the occupant 12 can be carefully corrected with a small force using the belt tensioner 30. Alternatively, the occupant 12 can be automatically placed in an upright position with a greater force.

[0051] Therefore, the safety effect of the seat belt system 10 is improved by means of this method.

[0052] The method may be used with a seat belt system 10 for any seat in a vehicle to improve the safety of the occupant 12 .

[0053] exist Figure 3 and Figure 4 1 shows, by way of example, a seat belt system 10 for a rear seat row 44 in a motor vehicle 14 for another embodiment, which seat belt system differs only in details from Figure 1 and Figure 2Therefore, the same structures with the same functions are assigned corresponding reference numerals below.

[0054] The rear seat row 44 is arranged in the motor vehicle 14 behind a front seat row 46 , which may be the driver's seat 16 , for example.

[0055] The backrest 48 of the front seat 46 is arranged with its back side 50 opposite the occupant 12 and comprises an airbag 36 which is provided for the occupant 12 on the rear seat 44 .

[0056] The display 38 is arranged in the headrest 52 of the front seat 46 and is therefore arranged in the field of vision of the occupant 12 .

[0057] The seat belt system 10 is in turn connected to an onboard computer which implements the already described method for operating the seat belt system 10. This means that the occupant 12 leaves the vehicle. Figure 3 The best sitting posture is shown in Figure 4 ), and this causes the seat belt to be pulled out beyond a threshold, initiating a reaction to notify the occupant 12 or correct a critical sitting posture.

[0058] Here, the seat position of the rear seat 44 and the seat position of the front seat 46 are taken into account when determining the threshold value, so as to take into account the relative arrangement of the seats 44, 46 and in particular the backrests 32, 48 to one another. This ensures that the free space guaranteed for the occupant 12 takes into account the surroundings of the occupant 12, so that, for example, the occupant is not endangered by the airbag 36. In this way, the safety of the occupant 12 on the rear seat 44 is improved by the proposed method.

[0059] The present invention is not limited to the embodiments shown. In particular, individual features of one embodiment can be included in another embodiment according to the present invention independently of other features of the corresponding embodiment, that is, the described features can be combined in any way.

Claims

1. A method for operating a seat belt system (10) for an occupant (12) in a motor vehicle (14), wherein: A seat belt system (10) comprises a seat belt for restraining an occupant (12), a seat belt lock (26) and a sensor (28) for detecting seat belt extension, wherein the method starts to react when the seat belt extension exceeds a threshold value, wherein the threshold value takes into account a minimum seat belt extension after the seat belt lock (26) is closed, characterised in that the threshold value takes into account a minimum seat belt extension within 30 seconds after the seat belt lock (26) is closed, and the threshold value=minimum seat belt extension+permitted distance, wherein the permissible distance depends on the current speed of the motor vehicle (14) in such a way that the permissible distance decreases as the speed increases.

2. The method according to claim 1, characterized in that The threshold value continuously takes into account a minimum belt extension after the belt buckle (26) has been closed.

3. The method according to claim 1 or 2, characterized in that: The threshold value takes into account the sitting position of the occupant (12) by means of sensors (34, 40).

4. The method according to claim 1 or 2, characterized in that: The threshold value takes into account the seat position of a seat (16, 44) for an occupant (12), the seat position of a seat (46) arranged in front of the seat of the occupant (12) in the motor vehicle (14), and / or the position of a steering wheel (18) arranged in front of the seat of the occupant (12) in the vehicle (10).

5. The method according to claim 1 or 2, characterized in that: The threshold takes into account the position of the airbag (36).

6. The method according to claim 1 or 2, characterized in that: The threshold value takes into account the position of an airbag (36) which is arranged opposite the occupant (12) in the direction of travel (F).

7. The method according to claim 1 or 2, characterized in that: The reaction includes the sending of an acoustic and / or optical signal by means of an output device (38) in order to transmit the information to the vehicle occupant (12).

8. The method according to claim 1 or 2, characterized in that: The reaction includes activating a seat belt tensioner (30) for tightening the seat belt (20), thereby increasing the restraining force of the seat belt (20).

9. The method according to claim 8, characterized in that The restraining force of the seat belt (20) is increased by a fixed value, a value that increases continuously over time, or a value that fluctuates over time.

10. The method according to claim 1 or 2, characterized in that: The threshold value takes into account a minimum belt extension within 20 seconds after the belt buckle (26) is closed.

11. The method according to claim 10, characterized in that The threshold value takes into account a minimum belt extension within 10 seconds after the belt buckle (26) is closed.

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