AUTOMATIC SEAT BELT RETRACTOR

Abstract

An automatic seat belt retractor includes a belt reel configured to wind a seat belt and a sensor configured to permanently record a rotational speed of the belt reel. The sensor cooperates with an element that is speed-coupled to the belt reel to record the rotational speed. The automatic seat belt retractor includes a brake unit configured to decelerate the seat belt being unwound from the belt reel with a restraining force and a control module configured to control the brake unit with respect to the restraining force as a function of the rotational speed.

Claims

1-14. (canceled)

15. An automatic seat belt retractor comprising: a belt reel configured to wind a seat belt; a sensor configured to permanently record a rotational speed of the belt reel (20), wherein the sensor cooperates an element speed-coupled to the belt reel for recording the rotational; a brake unit configured to decelerate the seat belt from being unwound from the belt reel with a restraining force; and a control module configured to control the brake unit as a function of the rotational speed.

16. The automatic seat belt retractor according to claim 15, wherein the speed-coupled element comprises a torsion rod operably coupled to the belt reel.

17. The automatic seat belt retractor according to claim 15, wherein the sensor comprises an absolute sensor configured to deliver information on the absolute belt extraction.

18. The automatic seat belt retractor according to claim 15, wherein the belt reel is rotatably mounted in a housing and the sensor is arranged on the housing.

19. The automatic seat belt retractor according to claim 18, wherein the belt reel is rotatably mounted in the housing and the belt reel serves for winding the seat belt, and wherein the automatic seat belt retractor further comprises a rotary part to the belt reel in a rotationally rigid fashion and configured to cooperate with the sensor to determine the rotational speed.

20. The automatic seat belt retractor according to claim 19, wherein the rotary part is secured to a belt strap of the seat belt.

21. The automatic seat belt retractor according to claim 19, wherein the rotary part arranged on the belt reel and forms an integral component of the belt reel.

22. The automatic seat belt retractor according to claim 19, wherein the rotary part comprises a passive rotational speed profile and the sensor comprises an electronic sensor.

23. The automatic seat belt retractor according to claim 15, wherein the sensor comprises a contactless sensor.

24. The automatic seat belt retractor claim 15, wherein the control module is configured to control the profile of the restraining force as a function of the time.

25. The automatic seat belt retractor according to claim 24, wherein the control module is configured to adapt the profile to at least one of a determined accident severity and a weight of an occupant secured with the seat belt as a function of the time.

26. The automatic seat belt retractor according to claim 25, wherein the control module is configured to determine at least one of the accident severity and the occupant weight based on at least one of the rotational speed and a time history over the time.

27. The automatic seat belt retractor claim 15, wherein the control module is configured to limit the restraining force.

28. The automatic seat belt retractor according to claim 15, wherein the automatic seat belt retractor comprises a weight sensor system configured to determine the weight of an occupant to be secured with the seat belt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.

[0038] FIG. 1 shows an automatic seat belt retractor in the form of a perspective representation;

[0039] FIG. 2 shows a side view of the automatic seat belt retractor according to FIG. 1 in the direction of the arrow II; and

[0040] FIG. 3 shows the profiles of the rotational speed and the restraining force as a function of the time.

DETAILED DESCRIPTION

[0041] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

[0042] FIG. 1 shows an automatic seat belt retractor 2 that includes a belt reel 20. The belt reel 20 serves for winding up and unwinding a seat belt 6. The automatic seat belt retractor 2 includes a sensor 8 that serves for recording a rotational speed D of the belt reel 4 about a rotational axis 10. In FIG. 1, the rotational speed D is symbolically indicated in the form of a rotational arrow of the belt reel 28, wherein the rotation in the direction of the arrow takes place when the seat belt 6 is unwound from the belt reel 20. The sensor 8 permanently records the rotational speed D—as long as it is in operation—i.e. any rotation of the belt reel 20 about its rotational axis 10, which lies within the measuring capabilities of the sensor 8, is always detected by the sensor 8.

[0043] The automatic seat belt retractor 2 is installed into a not-shown vehicle, in this case an automobile, and assigned to a not-shown vehicle seat thereof. A not-shown person is seated on the vehicle seat and secured with the seat belt 6.

[0044] A brake unit 12, which only is symbolically indicated in FIG. 1, serves for decelerating the seat belt 6 being unwound from the belt reel 20. The deceleration is realized by respectively applying a restraining force R to the seat belt 6 or the belt reel 20 as indicated with an arrow about the rotational axis 10 in FIG. 1. The automatic seat belt retractor 2 includes a control module 14 that serves for controlling the brake unit 12 with respect to the restraining force R. An electronic transmission channel 16 is established between the sensor 8 and the control module 14, i.e. it connects these two components, and serves for transmitting the rotational speed D, in this case from the sensor 8 to the control module 14. The control module 14 serves for controlling the restraining force R as a function of the rotational speed D.

[0045] The belt reel 20 is mounted in a housing 18 such that it is rotatable about the rotational axis 10. The sensor 8 is arranged on the housing 18. The belt reel 20 is connected to a speed-coupled element 21, which is mounted in or on the housing 18 such that it is rotatable about the rotational axis 10. The element 21 is only symbolically indicated and consists, e.g., of a shaft, a torsion rod or a connector or adapter part. Depending on the respective design, the element 21 may rotate with the same rotational speed D as the belt reel 20 or with a different rotational speed, from which the rotational speed D of the belt reel 20 can be positively derived. The belt reel 20 serves for winding the seat belt 6, i.e. the seat belt 6 is wound up on the belt reel 20 or unwound therefrom. The torsion rod integrated into the belt reel 20 can twist under a corresponding extraction force to limit the force level and to allow the belt extraction. The automatic seat belt retractor 2 includes a rotary part 22 that is connected to the belt reel 20 in a rotationally rigid fashion. The rotary part 22 serves for cooperating with the sensor 8 to determine the rotational speed D. A rotationally rigid connection means that any rotation of the belt reel 20 leads to a rotation of the rotary part 22. The rotary part 22 is directly arranged on the belt reel 20, i.e. directly connected thereto. In an alternative embodiment, the rotary part 22 forms an integral component of the belt reel 20, i.e. the rotary part is realized integrally with the belt reel. The rotary part 22 and the belt reel 20 form one common component in this case.

[0046] In an alternative embodiment, the rotary part 22 is connected to the element 21 and records its rotational speed. The latter then is—depending on the above-described embodiment—identical to the rotational speed D of the belt reel 20 or the rotational speed D of the belt reel 20 can be positively determined or calculated therefrom.

[0047] The rotary part 22 is a passive rotational speed profile. The sensor 8 is an electronic sensor that—during its operation and within its resolution or accuracy—reacts to any rotation of the rotational speed profile to measure its rotation about the rotational axis 10. In the exemplary embodiment, the rotary part 22 includes a plurality of circumferentially arranged sectors, which are also only indicated symbolically with respect to their number, wherein the individual sectors/sector boundaries can be detected by the sensor 8. The number of sectors defines the angular resolution or measuring accuracy of the sensor system (sensor 8 and rotary part 22) and can be chosen within broad limits. For example, the sectors have a different optical design to be detectable by an optical sensor 8 or a different magnetic configuration to be detectable by a magnetic sensor 8. The sensor 8 therefore is a sensor that operates in accordance with an electromagnetic or electro-optic functional principle. In this case, both magnetic or optical sensors are electronic sensors. The sensor 8 is a contactless sensor, i.e. no direct contact between the sensor 8 and the rotary part 22 respectively exists or is required.

[0048] The control module 14 serves for controlling the restraining force R—if applicable variably—as a function of the time t. FIG. 3 shows an exemplary profile of the restraining force R as a function of the time t. A not-shown motor vehicle, into which the automatic seat belt retractor 2 is installed, is involved in an accident at the time tu, which is the reason why the restraining force IZ begins to act in this moment and initially increases gradually during the course of the accident to gradually decelerate a not-shown passenger secured with the seat belt 6 of the automatic seat belt retractor 2 during the course of the accident. The restraining force R gradually drops back to zero after the deceleration of the passenger. At this point, the accident is concluded.

[0049] The control module 14 therefore serves for controlling the profile of the restraining force R as a function of the time t. FIG. 3 shows the respective profiles of the restraining force R and the rotational speed D as a function of the time t. In this case, the control module 14 serves for adapting the profile to a determined severity of the accident and/or a weight of the person secured with the seat belt 6 as a function of the time t.

[0050] The control module 14 serves for determining the accident severity and/or the weight based on the rotational speed D or the time history of the rotational speed D over the time T.

[0051] The control module 14 also serves for limiting the restraining force R, i.e. for allowing this restraining force to increase no higher than a maximum value Rmax. This applies, for example, as an option for limiting the restraining force R.

[0052] In an alternative embodiment, the automatic seat belt retractor 2 also features a weight sensor system 24. This weight sensor system serves for determining the weight of the automobile passenger secured with the seat belt 6. For this purpose, the weight sensor system 24 is installed into the seating surface of the seat, on which the person is seated. In the exemplary embodiment, the weight sensor system 24 is connected to the control module 14 to be respectively analyzed and activated thereby.

[0053] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.