DE29622181U1 - Belt retractor with multi-level force limiter - Google Patents

Description

20 December 1996

TRW Occupant Restraint Systems GmbH
Industriestrasse 20
D-73551 Alfdorf

Our reference: T 7804 DE Ki/Ki
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Belt retractor with multi-stage force limiter
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The invention relates to a belt retractor for a vehicle safety belt, with a belt reel rotatably mounted in a housing, at least one locking disk arranged at an axial end of the belt reel with a locking toothing on its outer circumference, at least one load-bearing locking pawl which can be controlled into the locking toothing to block the belt reel, and energy absorption means in the force flow path between the belt reel and the housing on which the locking pawl is supported in the restraint case, wherein the energy absorption means enable the belt reel to be rotated relative to the locking toothing if, with the belt reel (3) blocked, the blocking load exceeds a predetermined value.

The belt forces acting on a belted vehicle occupant when the belt reel is blocked can become so great in the event of a serious vehicle accident that they lead to injury to the vehicle occupant. The aim is therefore to limit the maximum forces acting on the belt. For this purpose, it is known from DE 296 13 044, for example, to arrange a torsion bar inside the belt reel, which is connected to the belt reel in a rotationally fixed manner on the one hand and to the locking disk in a rotationally fixed manner on the other. The torsion bar acts

as an energy absorption device, because in the restraint situation it is twisted and still allows a certain rotation of the belt reel. The force distribution in the belt webbing and thus the maximum forces acting on the vehicle occupant depend on the dimensioning of the torsion bar. However, since the maximum rotation of the belt reel depends on the weight of the vehicle occupant, it must be ruled out that a heavy vehicle occupant twists the torsion bar too much due to their large inertial mass and that it can move too far forward relative to the vehicle in the restraint situation. Conversely, the torsion bar should also allow a certain rotation of the belt reel if an extremely light vehicle occupant is to be restrained, so that the deceleration of the vehicle occupant's upper body in the restraint situation is not too abrupt.

The invention creates a belt retractor that can limit the maximum force acting on the belt webbing to different values, depending on external factors. This is achieved in a belt retractor of the type mentioned at the beginning by providing at least one adjusting device, by means of which the resistance to the rotation of the belt reel by the energy absorption means in the event of restraint can be changed. This also makes it possible to select different degrees of rotation of the belt reel and different decelerations of the vehicle occupant, depending, for example, on the intensity of the impact or the weight of the vehicle occupant.

The switching device is preferably activated accordingly by a control unit connected to a sensor system, wherein the sensor system is, for example, a crash sensor or a weight sensor integrated in the vehicle seat.

According to the preferred embodiment, the different resistances are achieved by providing several different force flow paths extending through energy absorption means, whereby energy absorption means located in the respective force flow path oppose a rotation of the belt reel with different resistances. At least one adjusting device determines the associated force flow path depending on the desired resistance.

According to the preferred embodiment, the energy absorption means comprise at least one torsion bar arranged within the belt reel, which is connected on the one hand in a rotationally fixed manner to the locking disk and on the other hand in a rotationally fixed manner to the belt reel.
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The preferred embodiment is further characterized in that several torsion bars are provided which are or can be connected to one another in parallel or in series with respect to the force flow.
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Further features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made. In these:

Figure 1 shows a first embodiment of the belt retractor according to the invention with a torsion bar having ends with different cross-sectional profiles, in longitudinal section;

Figure 2 shows a second embodiment of the belt retractor according to the invention with a non-circular torsion bar in longitudinal section;

Figure 3 is a reduced view of the torsion bar provided in the belt retractor according to Figure 2;

Figure 4 shows a third embodiment of the belt retractor according to the invention, with two torsion bars arranged one inside the other and fastened to one another, in longitudinal section;

Figure 5 is a sectional view along the line V-V in Figure 4 showing the connection of the inner torsion bar to the outer one;

Figure 6 shows a fourth embodiment of the belt retractor according to the invention, with three coaxially arranged, interconnected torsion bars in longitudinal section;
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Figure 7 shows a fifth embodiment of the belt retractor according to the invention, with three torsion bars arranged coaxially to one another, wherein the two inner torsion bars can be coupled away from the force flow by axial displacement, in longitudinal section;
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Figure 8 shows a sixth embodiment of the inventive

Belt retractor, with an inner torsion bar and several torsion bars arranged around the inner torsion bar, which can be coupled into the force flow path by axial displacement, in longitudinal section; and

Figure 9 is a sectional view along the line IX-IX in Figure 8.

Figure 1 shows a belt retractor according to a first embodiment. This comprises a housing 1 in which a belt reel 3 is rotatably mounted, on which a schematically shown belt webbing 5 is wound. At the axial ends of the belt reel 3 there are two locking disks, namely a first, left locking disk 7 and a second, right locking disk 9, which are coaxial to the belt reel 3 and have locking teeth 11 and 12 on their outer circumference. The locking disks 7, 9 are connected in a rotationally fixed manner via teeth 13 to the left and right axial ends of a torsion bar 15 arranged coaxially within the belt reel 3. In approximately the middle of the torsion bar 15, this is coupled to the belt reel 3 via a torque connection 17 in the form of teeth.

Two separately operable locking pawls 19 and 21 can be controlled into the locking teeth 11, 12, whereby the control can be carried out either vehicle- or belt-sensitively in order to block the belt reel 3 if necessary, so that essentially no further removal of the belt reel 5 arranged on the belt reel 3 is possible.

An electrically, hydraulically or pyrotechnically actuated actuating device 23 is connected to the pawls 19, 21 and controls them in the event of a restraint so that either the left or the right pawl 19, 21 or both pawls together are guided into the associated locking teeth 11, 12. The

The control itself can be carried out either by the rotating device 23 itself or by conventional vehicle or belt-sensitive devices, in which case the adjusting device 23 determines whether each pawl 19, 21 is pivoted. The adjusting device 23 is coupled to a control unit 25 and this to several sensors 27, of which only one is shown. The sensors 27 are, for example, crash sensors or weight sensors, the signals of which are processed in the control unit 25 and, in the event of restraint, send corresponding signals to the adjusting device 23.

In the event of a restraint, when a corresponding mechanism is triggered based on the vehicle or belt strap, the restraining effect of the belt strap 5 should be adapted to the intensity of the accident and the weight of the vehicle occupant (both are detected by corresponding sensors). The resistance that is opposed to a twisting of the belt reel 3 in the event of a restraint can have three different values in the belt retractor shown in Figure 1. For this purpose, the torsion bar 15 has different cross-sections in its longitudinal extension. Between the torque connection 17 and the right toothing 13, the torsion bar 15 has a smaller diameter (diameter A) than between the torque connection 17 and the left toothing 13 (diameter B).

If a relatively low resistance is to be provided to a rotation of the belt reel 3 in the event of restraint, only the locking pawl 21 is pivoted in, so that a flow of force is produced away from the housing 1 via the locking pawl 21, the locking teeth 12, the locking disk 9, the right half of the torsion bar 15, the torque connection 17, and into the belt reel 3. The locking disk 9 is blocked by the locking pawl 21, and the belt reel 3 can rotate by a certain angle, so that the force in the belt webbing 5 and the forces exerted on the vehicle occupant are limited. The right half of the torsion bar 15 therefore acts as an energy absorption means.

If a higher resistance is to be provided to the rotation of the belt reel 3, only the pawl 19 is pivoted, which blocks the left ratchet wheel 7. Accordingly, a different force flow path results than before, namely from the housing 1, via the

Locking pawl 19, the left half of the torsion bar 15 and finally to the belt reel 3. An even higher resistance can be achieved by simultaneously pivoting in both locking pawls 19, 21, so that the two force flow paths described above occur simultaneously.

In the following, the three stages, which are characterized by a low, a medium and a high resistance to twisting of the belt reel 3, are referred to as stage I, stage II and stage III respectively. Corresponding parts of the various designs of the belt retractor always have the same reference numbers in the following.

The embodiment shown in Figure 2 corresponds essentially to that shown in Figure 1, but the torsion bar 15' is not round, as in Figure 1, but flattened, compare Figure 3. The cross sections of the torsion bar 15' to the left and right of the torque connection 17' with the belt reel 3 are also different. Instead of the teeth 13 and 17, only slots are provided in the locking disks 7, 9 and in the middle of the belt reel 3, into which the torsion bar 15' must be inserted. However, since the functionality of the embodiment of the belt retractor shown in Figures 2 and 3 is identical to that shown in Figure 1, this does not need to be explained in more detail.

In the embodiment of the belt retractor shown in Figure 4, two torsion bars arranged coaxially to one another are provided. An outer, hollow torsion bar 27 is hollowed out axially from its two end faces up to an intermediate wall 29. An inner torsion bar 31 extends through the intermediate wall 29, which consists of a bundle of several torsion bars 31' to 31"" (see Figure 5), which are positively integrated into the intermediate wall 29. The torsion bar 31, which is composed of the bundle of individual torsion bars 3' to 31"", has a locking disk 33, 35 connected to it at each of its two axial ends, in the locking teeth of which an associated locking pawl 37, 39 can engage. The outer torsion bar 27 is coupled at its right outer end to the belt reel 3 via a torque connection 41. Its left outer end merges into a locking disk 43, in whose

• · • *

A locking pawl 45 can engage in the locking teeth. The locking pawls 37, 39, 45 are connected to the adjusting device 23, as is the case with the locking pawls 19, 21 according to Figure 1, but this is no longer shown in Figure 4 for the sake of simplicity. So that the left section of the torsion bar 31 has a different resistance to twisting of the belt reel 3 than the right side of the torsion bar 31, the distances between the intermediate wall 29 and the locking disks 33 and 35 are different.

The pawls 37, 39 and 45 are switched as follows in the event of a restraint:

Stage I: actuation of the pawl 39.
Stage II: Actuation of pawls 37 and 39.
Stage III: Actuation of the pawl 45.

Furthermore, intermediate stages would also be conceivable, namely only the actuation of the pawl 37 or an actuation of the pawl 35 with one or both pawls 37, 39.

In the embodiment shown in Figure 6, three torsion bars arranged one inside the other are provided. An outer, hollow torsion bar 51 is connected to the belt reel 3 in a rotationally fixed manner via the toothing 41. At its opposite end, it merges into a locking disk 53, which can be blocked by a pawl 55. A middle, hollow torsion bar 57 is connected to the torsion bar 51 in a rotationally fixed manner via a positive connection 59 at the end of the pawl side of the latter. At its opposite end, the middle torsion bar 57 merges into a locking disk 61, which can be prevented from rotating by a pawl 63.

An inner torsion bar 65 is connected to the

The locking disc is connected in a rotationally fixed manner to the end of the outer torsion bar 53 on the locking disc side. A locking disc 66 is rotationally fixed to its opposite end and can be prevented from rotating by a locking pawl 67.

The different resistances to twisting of the belt reel 3 are achieved as follows:

Stage I: actuation of the pawl 67.
Stage II: Actuation of the pawl 63.

Stage III: Actuation of the pawl 55.

If the pawl 63 or 67 is actuated, the torsion bars 51, 57 or 51, 65 are connected in series. If both pawls 63, 67 were actuated together, the torsion bars 57, 65 would be connected in parallel.

The embodiment of the belt retractor shown in Figure 7 also has three torsion bars arranged one inside the other, namely an outer, a middle and an inner torsion bar 71, 73 and 75 respectively. Instead of several locking discs, however, only one locking disc 77 is provided, which is permanently connected to the inner torsion bar 75 in a force-locking manner. Corresponding teeth on the right ends of the outer and middle torsion bars 71, 73 can engage with counter teeth in the locking wheel 77 when the torsion bars 71, 73 are moved to the left from the position shown in Figure 7 and are thereby coupled into the force flow path. The axial displacement itself takes place via the adjusting device 79, which is not connected to the locking pawl 81 that can be brought into engagement with the locking wheel 77, but is coupled to the front of the belt retractor via a cover 83. Depending on which torsion bar is to be coupled into the power flow, a slide 85 or 87 is actuated by the adjusting device 79. If the torsion bars 71, 73 are moved to the left, their teeth on their left end engage with corresponding counter teeth in a disk-like end 89 of the torsion bar 75, which is attached to the belt reel 3 in a rotationally fixed manner.

The different resistances to twisting of the belt reel 3 are achieved as follows:

Stage I: Actuation of the pawl 81, torsion bars 75 in the force flow path.

Stage II: Actuation of the pawl 81, torsion bars 73, 75 in the force flow path.

Stage III: Actuation of the pawl, torsion bars 71, 73, 75 in the force flow path.

At stage III, all three are connected in parallel

The slides 85, 87 can be moved, for example, by

In the event of a restraint, pyrotechnic charges that can be ignited separately are moved.

The embodiment shown in Figures 8 and 9 corresponds largely to that shown in Figure 7, but the outer and middle torsion bars 71, 73 are replaced by several torsion bars 91 and 93 that are thin in cross section and arranged on a common pitch circle around the center axis Z of the belt reel 3. These extend at their left end into corresponding holes 94 in the belt reel 3 and, in the position shown in Figure 8 in the power flow, into corresponding holes in the locking wheel 95. The adjusting device 97 comprises slides 85, 87 that can move the torsion bars 91 and the torsion bars 93 so far to the left that they come out of engagement with the locking disk 95.

The different resistances opposing the rotation of the belt reel 3 can be achieved as follows:

Stage I: Actuation of the pawl 81, torsion bars 81, 83 outside the force flow path.

Stage II: Actuation of the pawl 81, torsion bars 91 in the force flow path.

Stage III: Actuation of the pawl 81, torsion bars 91 and 93 in the force flow path.

Claims (15)

TRW Occupant Restraint Systems GmbH Industriestraße 20 D-73551 Alfdorf Our reference: T 7804 DE Ki/sc 10 Protection claims 1. Belt retractor for a vehicle safety belt, with
a belt reel (3) rotatably mounted in a housing (10), at least one locking disk (7, 9; 33, 35, 43; 53, 61, 66; 77; 95) arranged at an axial end of the belt reel (3) with a locking toothing (11, 12) on its outer circumference, at least one load-bearing pawl (19, 21; 37, 39, 45; 55, 63, 67; 81) which can be moved into the locking teeth (11, 12) to block the belt reel (3), and Energy absorption means in the force flow path between the belt reel (3) and the housing (10) on which the locking pawl (19, 21; 37, 39, 45; 55, 63, 67; 81) is supported in the event of restraint, wherein the energy absorption means enable a rotation of the belt reel (3) relative to the locking teeth (11, 12) when the blocking load exceeds a predetermined value when the belt reel (3) is blocked, characterized by at least one adjusting device (23; 79; 97) by means of which the resistance opposing the rotation of the belt reel (3) in the event of restraint by the energy absorption means can be changed. 2. Belt retractor according to claim 1, characterized in that the actuating device (23; 79; 97) can be activated by a control unit (25) connected to a sensor system (27). 3. Belt retractor according to claim 1 or 2, characterized by several different force flow paths extending through energy absorption means, whereby the energy absorption means located in the respective force flow paths oppose a rotation of the belt reel (3) with different resistances and whereby the adjusting device (23; 79; 97) selects the associated force flow path depending on the desired resistance. 4. Belt retractor according to one of the preceding claims, characterized in that the energy absorption means have at least one torsion bar (15; 15'; 27, 31; 51, 57, 65; 71, 73, 75; 91, 93) arranged within the belt reel (3), which is connected at a first point in a rotationally fixed manner to the locking disk (7, 9; 33, 35, 43; 53, 61, 66; 77; 95) and at a second point in a rotationally fixed manner to the belt reel (3). 5. Belt retractor according to claim 4, characterized in that several torsion bars (15; 15'; 27, 31; 51, 57, 65; 71, 73, 75; 91, 93) are provided, which are or can be connected to one another in parallel or in series with respect to the force flow. 6. Belt retractor according to claim 4 or 5, characterized in that a torsion bar (15; 15'; 31) is connected at its axial ends in a rotationally fixed manner to a locking disk (7, 9; 33, 35) and between its axial ends in a rotationally fixed manner to the belt reel (3), that it offers different resistances to the rotation of the belt reel (3) on both sides of its connection (17; 17'; 29) to the belt reel (3), and that locking pawls (19, 21; 37, 39) belonging to the locking disks (7, 9; 33, 35) can be controlled separately from one another into the associated locking teeth (11, 12) by the adjusting device (23). 7. Belt retractor according to claim 6, characterized in that the different resistances are determined by different cross-sectional profiles of the torsion bar (15; 15'; 31) on both sides of its connection (17; 17'; 29) to the belt reel (3). 8. Belt retractor according to claim 6 or 7, characterized in that the distances from the connection (17; 17'; 29) of the torsion bar (15; 15'; 31) to the belt reel (3) to the two locking disks (7, 9; 33, 35) provided at the axial ends of the torsion bar (15; 15'; 31) are different. 9. Belt retractor according to one of claims 4 to 8, characterized in that the energy absorption means comprise a plurality of torsion bars (15; 15'; 27, 31; 51, 57, 65; 71, 73, 75; 91, 93) which can be coupled into the force flow path by the adjusting device (23; 79; 97) in order to change the resistance to twisting of the belt reel (3) as a whole. 10. Belt retractor according to one of claims 4 to 9, characterized in that several torsion bars (71, 73, 75; 91, 93) arranged parallel to one another are provided, which can be axially displaced by the adjusting device (79; 97) from a non-force-transmitting to a force-transmitting position, in which they are coupled on the one hand to the belt reel (3) and on the other hand to a locking disk (77; 95). 11. Belt retractor according to one of claims 4 to 10, characterized in that the torsion bars (27, 31; 51, 57, 65; 71, 73, 75) are arranged coaxially to one another and within one another, in that at least one torsion bar (27; 51, 57; 71, 73) is hollow. 12. Belt retractor according to one of claims 4 to 11, characterized in that a plurality of torsion bars (91, 93) are arranged in a uniformly distributed manner around a torsion bar (75) coaxial with the belt reel and can thus be coupled into the force flow path. 13. Belt retractor according to one of claims 4 to 12, characterized in that several torsion bars (27, 31; 51, 57, 65) arranged one inside the other are provided, which are connected at least at one axial end in a rotationally fixed manner to an associated locking disk (33, 35, 43; 53, 61, 66), and that the adjusting device (23) controls the associated pawls (37, 39, 45; 55, 63, 67) can be actuated separately from one another or allows their actuation. 14. Belt retractor according to claim 13, characterized in that a torsion bar (27) has axial recesses from both end faces extending up to an intermediate wall (29), and that a bundle of torsion bars (3Γ to 31"") is positively integrated in the intermediate wall (29), the bundle of torsion bars (3Γ to 31"") being positively connected to an associated locking disk (33, 35) at at least one of its axial ends. 15. Belt retractor according to one of claims 4 to 14, characterized in that several torsion bars (51, 57, 65) arranged coaxially to one another are provided, each of which is connected at one end to a locking disk (53, 61, 66), at least one torsion bar (57, 65) being coupled to another torsion bar (51) in a force-transmitting manner with its end opposite the locking end, and that different resistances can be achieved by coupling associated locking pawls (55, 63, 67) into at least one toothing of a locking disk (53, 61, 66).