MXPA01005782A - Seat belt retractor - Google Patents

Abstract

A seat belt retractor has a belt reel (3) for the seat belt webbing. A load limiter (5) allows limited extraction of belt webbing with energy absorption when the belt reel is blocked. The absorption of energy is adjustable as a function of crash-related data and the rotating movement of the belt reel (3) is scanned for this purpose when the extraction of belt webbing is limited.

Description

SECURITY BELT RETRACTOR The invention relates to a safety belt retractor. DE 196 04 483 Cl illustrates a safety belt retractor that is provided with a load limiter that allows limited removal of the belt frame with energy absorption when the belt reel is blocked. The absorption of energy can be adjusted as a function of data related to impact perceived by detectors. These data related to impact may be data regarding the body of the vehicle occupant, seat position data, impact condition data such as impact severity and the like. These data are determined by detectors arranged outside the retractor of the safety belt and are evaluated to adjust the energy absorption of the load limiter. This should allow the restraint characteristic of the seat belt to be influenced in a controlled manner when the seat belt is locked, in particular after tightening the seat belt, optionally in conjunction with the restriction function of an airbag. In accordance with the present invention, a safety belt retractor is provided in which limited extraction of the weft of the belt with absorption of energy related to impact, is achieved at reduced cost when the belt reel is blocked. The revolving movement of the belt reel is scanned to give a measurement signal or signals for the extracted length of the belt web and / or the extraction speed of the belt web by time differentiation and / or extraction acceleration of the belt frame by additional differentiation over time. A drive signal with which the load limiter is adjusted is derived from this signal or measuring signals. The time that begins with the removal of the belt frame with the belt reel blocked, is used to differentiate with time. The extracted length of the belt frame is determined by scanning components that rotate with the belt reel and comprise marks, teeth of the set of locking teeth or other elements representing rotational angle increments. The measuring signal or the measuring signals and in particular the signal corresponding to the acceleration of the belt weft extraction, is compared with a characteristic field of belt force. This characteristic field of belt strength reproduces, the desired characteristic of the limited extraction of the belt frame. The load limiter is adjusted as a function of the comparison.

The load limiter may be an energy absorber with variable energy absorption. For example, adjustable braking devices with which the limited extraction of the belt frame is decelerated with the characteristic field of belt strength desired are suitable for this purpose. Preferably, an energy absorber with variable energy absorption operates by the principle of a hydraulic pump in which the rotor of the hydraulic pump is coupled to the belt reel, for example by operating a coupling, and the rotor conveys a hydraulic medium through a throat device set as a function of the measurement signal or measurement signals. The hydraulic pump alone can form the adjustable load limiter. However, it is also possible to combine the hydraulic pump with an energy absorber having a predetermined energy absorption characteristic, for example with a torsion bar. The hydraulic pump then forms the variable part of the load limiter. Instead of a hydraulic pump, an electric motor can be connected to the winding shaft, for example by a coupling in order to achieve the desired energy absorption when the extraction of the belt frame is limited. A corresponding counter electromotive force can be generated in the electric motor for this purpose in order to achieve the necessary braking force. The electric motor can also be coupled to an energy absorber, with fixed predetermined energy absorption, for example a torsion bar. It is preferable to use a flat-built electric motor of the type known, for example, from DE 43 02 042 Al. DE 44 26 621 Al discloses a hydraulic pump as a clamping controller for a safety belt. With the present invention, however, the hydraulic pump is used for energy consumption, hydraulic medium that is transported through a butterfly valve controlled by the measuring signal or measurement signals by the rotation caused by the arrow of winding. The hydraulic pump can therefore be used if the limited extraction of the belt frame with energy absorption that can be adjusted to the respective incidence of an impact will be achieved when the belt reel is locked. The energy absorption of the load limiter may also be adjustable in design if a plurality of cumulatively switchable energy absorbers having a predetermined energy absorption characteristic may selectively commute cumulatively in order to achieve the desired restriction characteristic during the decelerated extraction of the belt plot. With the present invention, in contrast to the previous technique discussed above, the information required to obtain the restriction characteristic necessary for decelerated removal of the belt web is obtained by the behavior, in particular rotary behavior of the belt reel. The severity of the impact, the weight and the size of the occupant of the vehicle are indicated directly by the rotary movement of the belt arrow. A direct relationship between the impact sequence and the load limitation setting is therefore obtained. BRIEF DESCRIPTION OF THE DRAWINGS Modes of the invention will be described in more detail below with reference to the figures in which: Figure 1 shows a first embodiment of the invention with a hydraulic pump for adjusting the desired energy absorption; Figure 2 shows a second embodiment of the invention with an electric motor for adjusting the energy absorption; Figure 3 shows a third embodiment of the invention with spherical rotary cam adjustment, to adjust the desired energy absorption; Figure 4 shows a fourth embodiment of the invention with cumulatively switchable energy absorbers; and Figure 5 is a force diagram showing various stages of energy absorption as a function of web removal speed. DETAILED DESCRIPTION OF THE INVENTION In the embodiments shown in the figures, only the components of the seat belt retractor required to understand the invention are illustrated. The safety belt retractor has a belt reel 3 in which the weft of the safety belt is wound, which is not shown in detail. Blocking discs having sets of locking teeth 4 at their periphery are connected to the end flanges of the belt reel 3 by shear pins 15. To lock the belt reel 3 against further rotation, a locking pawl 14 associated with each set of locking teeth 4, it engages with the set of locking teeth. Blocking of this type is optionally carried out after the tightening of the safety belt, for example in the case of an impact. To reduce the load transmitted by the belt frame to the body of a vehicle occupant during the forward displacement of the vehicle occupant, a limited extraction of the belt frame with braking effect or energy absorption is provided, which takes effect between the body of the vehicle or retractor frame of the seat belt 28 and the belt reel 3. This removal of the belt frame with energy absorption is ensured in the respective modalities by a load limiter 5. In the illustrated modes, the adjustment of the energy absorption to a predetermined desired restriction characteristic by a belt force characteristic curve is possible as a function of the severity of the impact and / or the body weight of the vehicle occupant. For this purpose, the rotational movement of the belt reel is explored after blocking (locking engagement of the pawl 14 in the set or set of locking teeth 4) and the energy absorption of the load limiter 5 set as a function of the same. In the embodiments shown in Figures 1 and 2, the rotation of the belt reel is scanned by the scanner 2. For example, a mark 16 representing rotational angle increments can be scanned using the scanner. By exploring the rotational angle increments of the mark, the scanner sends a signal to provide the belt frame length extracted. A measurement signal proportional to the angular velocity (rotation speed) can be obtained by differentiating this signal in a differentiator 17. A measurement signal proportional to the rotational acceleration is obtained by further differentiation of this speed signal with time in a second differentiator 18. This signal proportional to the rotational acceleration is proportional to the force that goes into effect in the belt frame or in the belt reel during the forward movement of the body of the vehicle occupant. The described arrangement forms a detector device 1 with which the aforementioned measurement signals can be obtained. Measurement signals that contain information regarding the severity of the impact and regarding the body weight of the occupant of the vehicle, therefore can be obtained by exploring the rotational movement of the belt reel 3. The load limiter 5 can then be optionally adjusted as a function of a predetermined belt force characteristic curve as a function of one or more of these signals. In the described embodiments, the locking pawl 14 engages with the set of locking teeth 4 after tightening the belt on both sides or on one side of the winding shaft. During the forward movement of the body of the vehicle occupant, a force acts on the belt reel 3, such that the shear pins 15 are sheared off and the belt reel is able to rotate with respect to the locking disk 19 held by the locking pawl 14. A coupling 20 is connected by this relative rotation of the belt reel 3 with respect to the locked locking disk 19 such that the belt reel 3 is coupled to a pulse member 21 of an energy absorber. designed as a hydraulic pump 7. The couplings that are connected due to the relative rotation of the two parts are known. The hydraulic pump which is capable of operating, for example by the Eaton principle, conveys an incompressible medium, for example oil, in a closed circuit 23. This circuit comprises a controllable valve 24. The cross-section of flow can be adjusted by the valve 24 to produce flow losses and therefore to achieve the desired energy consumption. The hydraulic pump 7 and the connected circuit 23 with adjustable flow cross section therefore achieve an adjustable load limitation during limited removal of the belt frame. The flow cross section can be adjusted as a function of the belt force characteristic curve stored in a memory 25. This curve The belt force characteristic that is treated in relation to the extracted length of the belt frame is compared with the force tendency of the measurement signal obtained from the second differentiator 18 and the signal proportional to the length extracted from the frame of the belt. belt from the scanner 2. The two signals are evaluated in an evaluation device 26 that generates a signal representative of the force exerted on the belt frame, as a function of the length extracted from the belt frame. This signal is compared in the comparator 22 with the characteristic belt force adjustment curve stored in the memory 25. The drive signal with which the valve 24 is adjusted is derived from the comparison signal. The adjustment is carried out in such a way that the curve processed in the evaluation device 26 for the force variation corresponds to the belt force characteristic curve stored in the memory 25. The hydraulic pump 7 together with the closed circuit 23 can However, it is also possible to combine the hydraulic pump and the circuit 23 by an adjustable cross-section of the flow (valve 24) with an energy absorber having a predetermined energy absorption, for example with a torsion bar acting on the winding shaft 3. This torsion bar can be connected to the winding shaft in the manner shown in the embodiment of Figure 2. In the embodiment of Figure 2, an electric motor 8 is used as a variable energy absorber in place of the hydraulic pump 7 Together with the torsion bar 13, this variable energy absorber forms the adjustable load limiter. The torsion bar 13 is non-rotatably connected to the belt reel 3 at one end by a locking joint 27. At this other end, the torsion bar is connected non-rotatably to the locking disc 19. This locking disc also it can be connected non-rotatably to the belt reel 3 by shear pins 15 during normal operation. During locking engagement of the locking pawls 14 in the sets of locking teeth 4, the shear pins 15 are sheared due to the forces exerted on the belt reel during the forward movement of the vehicle occupant, in such a way that the belt reel 3 rotates with respect to the locked locking discs 19. One end of the torsion bar 13 is held non-rotatably by the right hand locking disc 19, while the other end rotates with the belt reel 3 due to interlocking joint 27. Energy absorption predetermined by the torsion bar 3 therefore comes into effect. As already explained in conjunction with the embodiment of Figure 1, the comparator 22 provides an actuation signal that serves to adjust an additional braking force that effects or acts on the belt reel 3 through the connected coupling 20, so such that the effect of the torsion bar 13 is reduced or increased. The electric motor 8 moves in an appropriate direction of rotation. This is done based on the comparison between the predetermined belt force characteristic curve in the memory 25 and the actual variation of the belt weft force that is obtained in the evaluation device 26. A motor controller 36 is operated as a function of comparison. The electric motor 8 can be a flat frame motor 8 as it is known from DE 43 02 042 A1. Activation of the valve 24 in the embodiment of FIG. 1 and activation of the electric motor 8 in the embodiment of FIG. 2 can also be carried out as a function of the speed of removal of the belt frame. For this purpose, the signals from the two differentiators 17, 18 are evaluated in the evaluation device 26. A stepped increase in energy absorption or load limiting force of the type shown, for example in the embodiment of Figure 5 and stored in memory 37, it can be achieved. In the embodiment of Figure 3, the load limiter 5 comprises a braking device 6 constructed in the form of a multi-disc clutch. Some of the multiple discs are mounted stationary in the frame 26 by a housing 29. Other discs are able to rotate with the arrow of the belt 3. During normal operation, the multiple discs are freely movable relative to each other. During locked engagement of the ratchet 14 in the set of locking teeth 4 and the accelerated forward movement of the vehicle occupant, the discs are pressed together with a variable contact pressure by a rotary cam adjuster 9 after separation with shearing of the shear pins 1. The contact pressure with which the clutch discs rest on each other is changed by a spherical rotary cam 30 as a function of the acceleration of rotation of the belt reel 3 during the forward movement of the occupant of the vehicle. For this purpose, the spherical rotary cam 30 which is mounted on a rotary cam socket 31, travels on a substantially tapered cam mounting face 32 on the rotary cam plug. A spring 33 is compressed as a function of the rotation speed in such a manner that the pressure with which the clutch discs rest on each other is changed. In this embodiment, the adjustment of the load limiter energy absorption as a function of the rotation acceleration of the belt reel or of the belt removal speed is achieved using purely mechanical means. In the embodiment shown in Figure 4, the load limiter 5 comprises energy absorbers 10, 11 and 12 which can be cumulatively switched. The two energy absorbers 10, 11 are designed as torsion bars. The energy absorber 12 is designed as a torsion sleeve arranged coaxially with the torsion bar 11. The three energy absorbers are located in a cavity in the belt reel 3. At their inner ends, the two torsion bars 10, 11 are non-rotatably connected to the belt reel 3 by a common interlocking part 35. The two outer ends of the torsion bars 10, 11 are non-rotatably connected to the terminal locking discs 19. These locking discs 19 can be blocked against rotation in the manner previously described by the associated locking pawls 14. The locking pawls can also be selectively engaged in engagement with one of the two sets of locking teeth 4 as known eg from DE 196 50 494 Al. The belt reel 3 is rotated during forward movement of the vehicle occupant; the energy consumed during rotation of the torsion bars 10, 11 or one of the two torsion bars having a load limiting effect. If the rotational speed exceeds a specific value, for example in the case of a 95th percentile man, a centrifugal clutch 34 reacts and connects the torsion sleeve 12 as an additional energy absorber. The centrifugal clutch 34 is located in the immediate vicinity of the end of the torsion bar 11 which is connected non-rotatably to the locking disc 19. The clutch 34 can also be driven by a speed sensor that scans the speed of rotation of the spool of belt 3. An additional torsion sleeve which is connected in an intermediate stage of rotation speed, can also be provided on the side of the torsion bar 10. Figure 5 is a force diagram showing various stages of energy absorption as a function of belt removal speed (spool speed). Energy absorption steps of this type depending on the belt removal speed determined by the belt reel scan can be achieved in the illustrated modes. The dependence of individual stages on the speed of Belt removal and stage height can be obviously modified. With the modalities illustrated, the necessary restriction characteristics can be produced by the load limiter as a function of the impact event, in the range of a woman from 5 percentile to a 95 percentile man.

Claims (10)

1. CLAIMS 1. - A safety belt retractor with a belt reel for the safety belt frame, a load limiter that allows limited removal of the belt frame with energy absorption when the belt reel is locked, and means of adjustment, which adjust the load limiter as a function of data related to impact, the rotary movement of the belt reel is traversed by a scanner, a measuring signal or measurement signals for the extracted length of the belt frame and / or the removal speed of the belt frame and / or the extraction acceleration of the belt frame that is formed from the scanned rotation movement and because the load limiter is adjusted as a function of this measurement signal or these signaling signals. measurement.
2. 2. - Safety belt retractor according to claim 1, characterized in that the explorer travels or explores co-rotating components of the belt reel.
3. 3. Safety belt retractor according to claim 2, characterized in that the co-rotating components are in identical rotational angle intervals.
4. 4.- Safety belt retractor of according to claim 2 or 3, characterized in that the co-rotating components that are scanned are marks or teeth of a set of locking teeth of the belt reel applied to the belt reel at equal angular intervals.
5. 5. - Safety belt retractor according to one of claims 1 to 4, characterized in that the measurement signal or measurement signals are compared with a characteristic field of belt force and the load limiter is adjusted as a function of the comparison.
6. 6. - Safety belt retractor according to one of claims 1 to 5, characterized in that the load limiter comprises at least one energy absorber with a variable energy absorption that is adjusted as a function of the measurement signal or of the measurement signals.
7. 7. - Safety belt retractor according to claim 6, characterized in that the variable energy absorber is designed as a hydraulic pump, an electric motor or as a rotary cam adjuster.
8. 8. - Safety belt retractor according to one of claims 1 to 7, characterized in that the load limiter comprises when less an energy absorber with predetermined energy absorption.
9. 9. - Safety belt retractor according to one of claims 1 to 8, characterized in that the load limiter comprises a plurality of accumulatively switchable energy absorbers.
10. 10. Safety belt retractor according to one of claims 1 to 9, characterized in that the energy absorption of the load limiter can be adjusted in stages as a function of the speed of extraction of the belt frame (rotational speed of the belt). belt reel).