Belt retractor for automobile seat belts

Abstract

To provide a belt retractor in which force-limited relative rotation of a belt shaft with respect to a locked profile head is possible with a higher force limiting level. [Solution] The belt retractor comprises a belt shaft (2) rotatably mounted on a housing frame (1), a profile head (3) that can be locked relative to the belt shaft (2), a multi-stage first force limiting device (4) coupled to the profile head (3) and the belt shaft (2), the first force limiting device (4) enabling force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3), and at least one second force limiting device (5), wherein in an initial state the second force limiting device (5) is disengaged, whereby the force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3) is performed without force-limited involvement of the second force limiting device (5).

Description

[Technical field]

[0001] The present invention relates to a belt retractor for a seat belt of a motor vehicle, comprising a belt shaft rotatably mounted on a housing frame, a profile head that can be locked relative to the housing frame, a multi-stage first force limiting device that can be coupled to the profile head and to the belt shaft, the first force limiting device allowing a force-limited relative rotation of the belt shaft with respect to the locked profile head, and a second force limiting device.

[0002] A belt retractor having the above-mentioned characteristics is known, for example from WO 2020 / 021003 A1, in which a multi-stage first force limiting device comprises two torsion bars which can be decoupled from each other to set different force limiting levels. In addition, a second force limiting device is provided which is initially coupled to the first multi-stage force limiting device and can be actively decoupled from the first multi-stage force limiting device. With such a belt retractor, three force limiting levels can be set for the force-limited relative rotation of the belt shaft.

[0003] The problem addressed by the present invention is to eliminate the disadvantages described with reference to the prior art, in particular to identify a belt retractor in which force-limited relative rotation of the belt shaft with respect to the locked profile head is possible with a higher force limiting level.

[0004] A solution to this problem is provided by a belt retractor having the features of the independent claim 1, further solutions and advantageous developments are specified in the dependent claims and the description, the individual features of the advantageous developments being capable of being combined with one another in a technically rational manner.

[0005] The problem is solved in particular by a belt retractor having the features mentioned at the beginning, in which the second force limiting device is initially decoupled, whereby a force-limited relative rotation of the belt shaft to the locked profile head can take place without the involvement of the force limiting of the second force limiting device.

[0006] In other words, the basic idea of ​​the present invention is that the second force limiting device is not directly or indirectly connected to the belt shaft in an initial start-up state, so that the force-limited relative rotation of the belt shaft is brought about solely by at least one force-limiting element of the first force limiting device, without intentional activation of the second limiting device, and thus the force-limited relative rotation at the start of the relative rotation, during the relative rotation and at the end of the relative rotation can be made completely independent of the second force limiting device.

[0007] According to an advantageous development, the invention proposes that a second force limiting device can be coupled to the profile head and / or the belt shaft, so that in the next coupled state, the force-limited relative rotation of the belt shaft to the locked profile head is effected by the participation of the force limiting of the second force limiting device. It is therefore proposed that the force-limited effect of the second force limiting device can be optionally added to a stage of the multi-stage first force limiting device. The number of force limitation levels achievable by the stages of the first force limiting device can thus be doubled by the second force limiting device.

[0008] Multi-stage first force limiting devices are known from the prior art. For example, a two-stage first force limiting device can comprise two torsion bars, and a switching device is provided, via which it is possible to switch, for example by a pyrotechnic drive, whether both torsion bars or only one torsion bar is involved in the force-limited relative rotation of the belt shaft. Thus, the first force limiting device can be used to set two force limiting levels. For the design of the multi-stage first, in particular the two-stage first force limiting device, reference is made in its entirety to WO 2020 / 021003 (A1), already mentioned at the beginning.

[0009] In particular, it is proposed that a drive is provided which can be activated, for example electronically, whereby the second force-limiting device can be coupled in such a way that the second force-limiting device also participates in the force-limited relative rotation of the belt shafts. In this case, it is proposed in particular that the drive is a pyrotechnic drive whereby a transition of the belt retractor from the initial state to the coupled state can be initiated, whereby in addition to the first force-limiting device, the second force-limiting device participates in the force-limited relative rotation.

[0010] In a preferred embodiment, the second force limiting device comprises a wheel element which in the initial state is rotatably mounted relative to the housing frame and rotates together with the belt shaft and / or elements of the first force limiting device. In the coupled state, however, the wheel element is blocked from rotating. The wheel element can be, for example, a gear wheel having teeth on its outer periphery.

[0011] In particular, it is proposed that the wheel element can be blocked in its rotation by the clamping element. The second force-limiting device therefore preferably comprises a clamping element which can be driven by a pyrotechnic drive. In the initial state, the clamping element is arranged at a distance from the wheel element, which is in particular designed as a gear wheel. The pyrotechnic drive makes it possible to move the clamping element towards the rotating wheel element so that the teeth of the wheel element engage with the clamping element. The clamping element is therefore initially entrained along the rotating wheel element.

[0012] In this context, it is provided in particular that the housing surrounding the wheel element has a clamping design, which is arranged and designed in such a way that the clamping element aligned along the wheel element comes into or on the clamping design, thereby blocking further movement of the clamping element engaged with the teeth of the wheel element and thereby also blocking the rotation of the wheel element. For example, the clamping design can be designed as a recess in the housing, in which the clamping element is aligned by the wheel element and in which the clamping element abuts, in particular, against a stop. Alternatively, it can be provided that the clamping design has a starting inclination, with which the clamping element is initially aligned by the wheel element, which inclination displaces the clamping element and therefore also the wheel element at right angles to the axis of rotation of the wheel element, whereby blocking of the wheel element occurs.

[0013] It may further be provided that the second force limiting device comprises a driver which drives the force limiting element in the coupled state to rotate together with the belt shaft and / or the first force limiting device. For example, the driver may be connected to a deformable belt serving as the force limiting element, which in the coupled state is driven by the driver during force-limited relative rotation, such that the force limiting element provides the force-limiting effect of the second force limiting device through a deformation action.

[0014] Thus, in one embodiment, it may be provided that a belt acting as a force-limiting element is coupled to the driver and to the wheel element, whereby if the rotation of the wheel element is blocked, in particular by a pyrotechnic drive and a clamping element, the driver continues to rotate relative to the fixed wheel element, thereby driving and deforming the belt.

[0015] Alternatively, it may be provided that the driver, which drives the force-limiting element in the coupled state, is decoupled from the belt shaft in the initial state. Thus, in the initial state, the driver is not driven by the belt shaft and / or the first force-limiting device, but is actively coupled to the belt shaft and / or the first force-limiting device. For this purpose, the driver can be coupled to the belt shaft, for example by means of a pawl, which is in particular mounted on a coupling ring, which in the initial state rotates together with the belt shaft and / or the first force-limiting device and is connected to the wheel element. For this purpose, the wheel element can have, for example, a pin-like projection, on which the coupling ring with a recess is arranged. If the rotation of the wheel element is blocked, for example by a pyrotechnically driven clamping element, the coupling ring comes off the wheel element, since it is non-rotatably connected to the belt shaft and / or the first force-limiting device. The subsequent relative rotation between the coupling ring and the wheel element brings the pawl into engagement with a locking projection on the wheel element.

[0016] Due to the relative rotation of the coupling ring with respect to the blocked wheel element, the pawl also engages the driver, whereby the driver, which is initially held stationary, is driven into a rotational movement together with the coupling ring, so that the driver is connected, for example, to a deformable belt element, which is in particular pulled through a chicane, thereby performing a deformation operation providing the force-limiting contribution of the second force-limiting device.

[0017] In one embodiment, the second force limiting device can be arranged between the profile head and the belt shaft. Alternatively, the second force limiting device can be arranged on the side of the belt shaft opposite the profile head. It is also possible in principle to provide two second force limiting devices, which are arranged on both sides of the belt shaft. This makes it possible to set an ideal weight distribution of the entire belt retractor.

[0018] For a compact design of the belt retractor it is proposed that the pyrotechnic drive of the first force-limiting device and the pyrotechnic drive of the second force-limiting device are arranged in a common housing.

[0019] Alternatively, it may be provided that the pyrotechnic drive of the first force limiting device and the pyrotechnic drive of the second force limiting device are arranged in separate housings. In this regard, it is also proposed that the belt retractor is designed for modular expansion. Depending on the application, the belt retractor can be expanded by a second force limiting device. For this purpose, a second force limiting device having a housing for accommodating the pyrotechnic drive can be plugged into at least one component (e.g. an element of the first force limiting device and / or the belt shaft, such as a torsion bar). The belt retractor is thus modularly expandable, the second force limiting device having a connection design complementary to the corresponding connection design of the remainder of the belt retractor. [Brief description of the drawings]

[0020] The invention and the technical environment are explained below by way of example with reference to the figure, which shows, diagrammatically: [Figure 1] FIG. 1 is a cross-sectional view through a belt retractor. [Diagram 2] FIG. 2 is an exploded view of a first embodiment of the second force limiting device. [Diagram 3] FIG. 2 is a plan view of a second force limiting device in an initial state. [Figure 4]FIG. 13 is a plan view of the second force limiting device in a coupled state. [Diagram 5] FIG. 13 is an exploded view of a second embodiment of the second force limiting device. [Figure 6] FIG. 6 is a perspective view of components of the second force limiting device according to FIG. 5 . [Figure 7] 1 is a graph illustrating possible force limiting levels.

[0021] The belt retractor shown in Fig. 1 comprises a belt shaft 2 rotatably mounted in a housing frame 1. The belt shaft 2 is non-rotatably connected to a profile head 3. To initiate a force-limited relative rotation of the belt shaft 2 with respect to the housing frame 1, the profile head 3 can be locked in a known manner against further rotation with respect to the housing frame 1.

[0022] The belt retractor comprises a multi-stage first force-limiting device 4, which comprises a first torsion bar 4.1 and a second torsion bar 4.2. The multi-stage first force-limiting device 4 also comprises a switching device, known per se, so that the force-limited relative rotation of the belt shaft 2 with respect to the locked profile head 3 can be effected by both the torsion bars 4.1 and 4.2 or by only one of the torsion bars.

[0023] The belt retractor also includes a second force limiting device 5 .

[0024] A first embodiment of the second force-limiting device 5 is shown in figures 2 to 4. The second force-limiting device comprises a wheel element 5.3 with external teeth, a driver 5.4, a force-limiting element 5.5 designed as a belt and a clamping element 5.2 and can be driven by a pyrotechnic drive 5.1 (see in particular figure 3). The pyrotechnic drive 5.1 of the second force-limiting device 5 is arranged in a common housing 6, in which the pyrotechnic drive for the switching device of the first force-limiting device 4 is also arranged. Alternatively, the pyrotechnic drive can also be arranged in a separate housing, which allows a modular design.

[0025] The driver 5.4 is non-rotatably connected to the second torsion bar 4.2 of the first force limiting device. In the initial state, the wheel element 5.3 rotates due to its connection with the driver 5.4 via the belt 5.5.

[0026] Now, when the pyrotechnic drive 5.1 is activated, the clamping element 5.2, which in the initial state is at a distance from the gear wheel of the wheel element 5.3 (see in particular FIG. 3), is pressed against the wheel element 5.3 (see FIG. 4). The teeth of the wheel element 5.3 engage with the clamping element 5.2. The wheel element 5.3 is blocked, since the clamping element 5.2 cannot follow the rotational movement due to the contact with the housing. This is therefore followed by a relative rotation of the driver 5.4 with respect to the blocked wheel element 5.3, which results in a deformation of the force limiting element 5.5. In this way, an additional force limiting level is provided by the second force limiting device 5.

[0027] The embodiment shown in figure 5 comprises a chicane 5.8 through which a belt 5.5 designed as a force limiting element can be pulled. The belt 5.5 is connected to a driver 5.4 and does not rotate together with the belt shaft 2 and / or the first force limiting device 4 in the initial state.

[0028] The second force limiting device of FIG. 5 also has a coupling ring 5.7 and a claw 5.6. In the initial state, the coupling ring 5.7 is non-rotatably connected to the wheel element 5.3. For this purpose, the coupling ring 5.7 is arranged on the pin 5.3.1 of the wheel element 5.3 (see FIG. 6). The coupling ring 5.7 is non-rotatably connected to the second torsion bar 4.2 of the first force limiting device 4, so that in the initial state, the wheel element 5.3 rotates together with the coupling ring 5.7.

[0029] Now, if the wheel element 5.3 is blocked by the clamping element 5.2 (as in the embodiment of FIG. 2), the pin 5.3.1 disengages from the wheel element 5.3 and the coupling ring 5.7 continues to rotate relative to the blocked wheel element 5.3. This relative movement results in the claw 5.6 engaging with the projection 5.3.2 of the wheel element 5.3, which in this state protrudes beyond the outer circumference of the coupling ring 5.7 and engages with the form-fitting design on the inside of the driver 5.4. In this state, the driver 5.4 rotates together with the coupling ring 5.6 (5.7), thereby pulling the belt 5.5 through the chicane 5.8. Thus, in this state, a force-limited relative rotation of the belt shaft occurs due to the involvement of the second force-limiting device 5.

[0030] FIG. 7 shows, by way of example, four force limiting levels 7.1, 7.2, 7.3 and 7.4 which can be adjusted using the belt retractor according to the invention. The first force limiting level 7.1 can be set by the multi-stage first force limiting device 4 by both torsion bars 4.1 and 4.2 being involved in a force-limited relative rotation. If one of the torsion bars 4.1 or 4.2 is decoupled by the switching device, the second force limiting level 7.2 is reached. If the second force limiting device 5 is coupled, the two force limiting levels achievable by the first force limiting device 4 can be increased, whereby a third force limiting level 7.3 and a fourth force limiting level 7.4 can be set. Thus, in a force-limited relative rotation of the third force limiting level 7.3 both torsion bars 4.1 and 4.2 of the first force limiting device 4 as well as the second force limiting device 5 are involved, while in a force-limited relative rotation of the fourth force limiting level 7.4 one of the two torsion bars 4.1 or 4.2 of the first force limiting device 4 as well as the second force limiting device 5 are involved. The four force limiting levels can be set at different times or at the start of the relative rotation. [Explanation of symbols]

[0031] 1 Housing Frame 2 Belt shaft 3 Profile Head 4 First Force Limiting Device 4.1 First Torsion Bar 4.2 Second Torsion Bar 5 Secondary force limiting device 5.1 Pyrotechnic drive system 5.2 Clamping elements 5.3 Wheel elements 5.3.1 Pins 5.3.2 Protrusion 5.4 Drivers 5.5 Force-limiting elements 5.6 Nails 5.7 Coupling Rings 5.8 Chicane 6. Housing 7.1 First Force Limiting Level 7.2 Second Force Limiting Level 7.3 Third force limiting level 7.4 Fourth Force Limitation Level

Claims

1. 1. A belt retractor for a seat belt of a motor vehicle, comprising: - a belt shaft (2) rotatably mounted on the housing frame (1); - a profile head (3) that can be locked relative to said housing frame (1); a multi-stage first force limiting device (4), which can be coupled to the profile head (3) and to the belt shaft (2), said first force limiting device (4) allowing a force-limited relative rotation of the belt shaft (2) with respect to the locked profile head (3); at least one second force limiting device (5), Equipped with 13. A belt retractor, characterized in that in an initial state, the second force limiting device (5) is decoupled, whereby the force-limited relative rotation of the belt shaft (2) with respect to the locked profile head (3) takes place without force-limited involvement of the second force limiting device (5).

2. 2. The belt retractor according to claim 1, wherein the second force limiting device (5) can be coupled to the profile head (3) and to the belt shaft (2), so that in the coupled state, the force-limited relative rotation of the belt shaft (2) to the locked profile head (3) is effected by force-limited engagement of the second force limiting device (5).

3. 3. The belt retractor according to claim 1 or 2, wherein the second force-limiting device (5) comprises a pyrotechnic actuation device (5.1) by means of which the transition of the belt retractor from the initial state to the coupled state can be initiated.

4. 3. The belt retractor according to claim 1 or 2, wherein the second force-limiting device (5) comprises a clamping element (5.2) which can in particular be pyrotechnically actuated.

5. 3. The belt retractor according to claim 1 or 2, wherein the second force limiting device (5) comprises a wheel element (5.3) which is rotatably mounted relative to the housing frame (1) in the initial state and whose rotation is blocked in the coupled state.

6. 3. The belt retractor according to claim 1 or 2, wherein in the coupled state a driver (5.4) which drives a force-limiting element rotates together with the belt shaft (2) and / or the first force-limiting device (4) in the initial state.

7. 3. The belt retractor according to claim 1 or 2, wherein a driver (5.4), which drives a force-limiting element (5.5) in the coupled state, is decoupled from the belt shaft (2) in the initial state.

8. 8. The belt retractor according to claim 7, wherein the driver (5.4) can be coupled to the belt shaft (2) by means of pawls (5.6), the pawls (5.6) being mounted on a coupling ring (5.7) which in particular rotates together with the belt shaft (2) in the initial state and is connected to a wheel element (5.3).

9. 3. The belt retractor according to claim 1 or 2, wherein the second force limiting device (5) is arranged between the profile head (3) and the belt shaft (2) or on a side of the belt shaft (2) opposite the profile head (3).

10. 3. The belt retractor according to claim 1 or 2, wherein the second force-limiting device (5) comprises as force-limiting element (5.5) at least one belt which is deformed during force limitation.

11. 3. The belt retractor according to claim 1 or 2, wherein the pyrotechnic drive of the first force-limiting device and the pyrotechnic drive of the second force-limiting device are arranged in separate housings (6).

Images