Belt retractor for a motor vehicle safety belt

Abstract

Seatbelt retractor for a motor vehicle seatbelt, with - a belt shaft (2) rotatably mounted in a housing frame (1), - a profile head (3) that can be locked against the housing frame (1), - a multi-stage first force limiting device (4), wherein the first force limiting device (4) can be coupled on the one hand to the profile head (3) and on the other hand to the belt shaft (2), and wherein the first force limiting device (4) enables a force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3), and - at least a second force limiting device (5), wherein in an initial state the second force limiting device (5) is decoupled and is not directly or indirectly connected to the belt shaft (2), so that without intentional activation of the second force limiting device (5) the force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3) takes place without force-limited participation of the second force limiting device (5), characterized in that the second force limiting device (5) comprises at least one belt that deforms during force limiting as a force limiting element (5.5).

Description

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

[0002] A seatbelt retractor with the aforementioned features is known, for example, from WO 2020 / 021 003 A1, in which a multi-stage first force limiting device comprises two torsion bars that can be decoupled from each other to set different force limiting levels. Furthermore, a second force limiting device is provided, which is coupled to the first multi-stage force limiting device in an initial state and which can be actively decoupled from the first multi-stage force limiting device. With such a seatbelt retractor, three force limiting levels can be set for the force-limited relative rotation of the belt shaft. A seatbelt retractor with the features of the preamble of claim 1 is known from DE 296 22 181 U1.

[0003] The object of the present invention is to eliminate the disadvantages described with reference to the prior art and in particular to provide a belt retractor in which the force-limited relative rotation of the belt shaft with respect to the locked profile head is possible with more force limitation levels.

[0004] A solution to this problem is given by the belt winder with the features of independent claim 1, wherein further solutions and advantageous developments are given in the dependent claims and in the description, wherein individual features of the advantageous developments can be combined with each other in a technically meaningful way.

[0005] The problem is solved in particular by a belt retractor with the aforementioned features, in which the second force limiting device is decoupled in an initial state, so that the force-limited relative rotation of the belt shaft relative to the locked profile head can take place without force-limiting participation of the second force limiting device.

[0006] In other words, the basic concept of the invention is that the second force limiting device is not directly or indirectly connected to the belt shaft in its initial state, so that without intentional activation of the second limiting device, the force-limited relative rotation of the belt shaft is effected solely by at least one force limiting element of the first force limiting device. Thus, the force-limited relative rotation can occur completely independently of the second force limiting device at the beginning, during, and at the end of the relative rotation.

[0007] According to an advantageous embodiment of the invention, the second force limiting device can be coupled to the profile head and / or the belt shaft, so that in a coupled state, the force-limited relative rotation of the belt shaft with respect to the locked profile head is achieved with the force-limiting participation of the second force limiting device. It is thus proposed that the force-limiting 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 limiting levels achievable by the stages of the first force limiting device can therefore be doubled by the second force limiting device.

[0008] Multi-stage first force limiting devices are well known in the art. For example, a two-stage first force limiting device can comprise two torsion bars, with a switching device provided by means of, for example, a pyrotechnic drive, to switch whether both torsion bars or only one torsion bar participates in the force-limited relative rotation of the belt shaft. Thus, two force limiting levels can be set with the first force limiting device. Regarding the design of a multi-stage first force limiting device, in particular a two-stage first force limiting device, reference is made in full to WO 2020 021 003 A1 already mentioned at the outset.

[0009] It is specifically proposed that an electronically activated drive be provided, enabling the coupling of the second force limiting device in such a way that the second force limiting device also participates in the force-limited relative rotation of the belt shaft. It is particularly proposed that the drive be a pyrotechnic drive by means of which a transition of the belt retractor from its initial state to a coupled state can be triggered, in which the second force limiting device participates in the force-limited relative rotation in addition to the first force limiting device.

[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 with the belt shaft and / or an element of the first force limiting device. In a coupled state, however, the wheel element is blocked from rotating. The wheel element can, for example, be a gear with teeth on its outer circumference.

[0011] It is specifically proposed that the wheel element be lockable in its rotation by means of a clamping element. The second force-limiting device thus comprises a clamping element, which is preferably driven by the pyrotechnic drive. In the initial state, the clamping element is arranged at a distance from the wheel element, which is preferably designed as a gear. The pyrotechnic drive allows the clamping element to be moved towards the rotating wheel element, so that the teeth of the wheel element engage with the clamping element. Thus, the clamping element is initially carried along by the rotating wheel element.

[0012] In this context, it is particularly intended that a housing surrounding the wheel element has a clamping device. The clamping device is arranged and designed such that the clamping element carried by the wheel element comes into contact with the clamping device, preventing further movement of the clamping element engaged with the teeth of the wheel element and thus blocking the rotation of the wheel element. For example, the clamping device can be designed as a recess in the housing into which the clamping element is carried by the wheel element, with the clamping element coming to rest against a stop.Alternatively, the clamping design can be provided with a ramp along which the clamping element is initially carried along by the wheel element, whereby the ramp causes the clamping element and thus also the wheel element to be displaced transversely to the axis of rotation of the wheel element, thereby causing a blockage of the wheel element.

[0013] It can further be provided that the second force limiting device includes a driver which, in the coupled state, drives a force limiting element and rotates with the belt shaft and / or the first force limiting device. In this way, the driver is connected to a deformable belt serving as a force limiting element, which, in the coupled state, is driven by the driver during the force-limited relative rotation, with the force limiting element providing the force-limiting effect of the second force limiting device through the deformation work.

[0014] In one embodiment, a band acting as a force-limiting element can be coupled to the driver on one side and to the wheel element on the other. If the wheel element is now blocked in its rotation, particularly by means of the pyrotechnic drive and the clamping element, the driver continues to rotate relative to the fixed wheel element, thereby driving and deforming the band.

[0015] Alternatively, a drive element that, when coupled, drives a force-limiting element, can be provided that it is decoupled from the belt shaft in its initial state. In its initial state, the drive element is therefore 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 drive element can, for example, be coupled to the belt shaft by means of pawls, the pawls being mounted, in particular, on a coupling ring that rotates with the belt shaft and / or the first force-limiting device and is connected to a wheel element in its initial state. For this purpose, the wheel element can, for example, have pin-like projections onto which the coupling ring with recesses is mounted.If the wheel element is blocked in its rotation, for example by means of the pyrotechnically driven clamping element, the coupling ring breaks off from the wheel element, since the coupling ring is rotationally fixed to the belt shaft and / or the first force limiting device. The subsequent relative rotation between the coupling ring and the wheel element then engages the pawls with locking projections on the wheel element.

[0016] The relative rotation of the coupling ring relative to the blocked wheel element also engages the pawls with the drive pin, thereby driving the initially stationary drive pin into a rotational movement together with the coupling ring. The drive pin, in turn, is connected, for example, to a deformable belt element, whereby the belt element is drawn through a baffle, thereby performing deformation work that provides 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. In principle, it would also be possible to provide two second force-limiting devices, with the force-limiting devices arranged on opposite sides of the belt shaft. This would allow for an ideal weight distribution of the entire belt retractor.

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

[0019] Alternatively, the pyrotechnic drive for the first force limiting device and the pyrotechnic drive for the second force limiting device can be arranged in separate housings. In this context, it is also proposed that the belt retractor be designed for modular expansion. Depending on the application, the belt retractor can be extended to include the second force limiting device. For this purpose, the second force limiting device, which has a housing to accommodate the pyrotechnic drive, can be attached to at least one component (for example, an element – ​​such as a torsion bar – of the first force limiting device and / or the belt shaft). The belt retractor is thus modularly expandable, with the second force limiting device having connection configurations that are complementary to corresponding connection configurations of the rest of the belt retractor.

[0020] The invention and its technical context are explained below using the figures as examples. They show schematic representations. Fig. 1: A cross-sectional view through a belt retractor, Fig. 2: an exploded view of a first embodiment of a second force limiting device, Fig. 3: a view of the second force limiting device in an initial state, Fig. 4: a view of the second force limiting device in a coupled state, Fig. 5: an exploded view of a second embodiment of a second force limiting device, Fig. 6: a perspective view of components of the second force limiting device according to Fig. 5, Fig. 7: A diagram illustrating possible force limitation levels.

[0021] The in Fig. The belt retractor shown in Figure 1 comprises a belt shaft 2 which is 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 so that it no longer rotates relative to the housing frame 1.

[0022] The belt retractor comprises a multi-stage first force limiting device 4, which includes a first torsion bar 4.1 and a second torsion bar 4.2. The multi-stage first force limiting device 4 also includes 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 carried out either with both torsion bars 4.1 and 4.2 or with only one of the torsion bars.

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

[0024] A first embodiment of a second force limiting device 5 is described in the Fig. 2 to 4 shown. The second force limiting device comprises a wheel element 5.3 having external teeth, a driver 5.4, a force limiting element 5.5 designed as a band, and a clamping element 5.2, which is actuated by means of a pyrotechnic drive 5.1 (see in particular ). Fig. 3) can be driven. The pyrotechnic drive 5.1 of the second force limiting device 5 is arranged in a common housing 6, in which a pyrotechnic drive for the switching device of the first force limiting device 4 is also arranged. Alternatively, the pyrotechnic drives can also be arranged in separate housings, thus enabling a modular design.

[0025] The driver 5.4 is rotationally fixed to the second torsion bar 4.2 of the first force limiting device. In the initial state, the wheel element 5.3 rotates with the driver 5.4 due to the connection via the band 5.5.

[0026] If the pyrotechnic drive 5.1 is now triggered, the clamping element 5.2, which in the initial state is spaced apart from the gears of the wheel element 5.3 (see in particular Fig. 3), pressed on the wheel element 5.3 (see Fig. 4) The teeth of the gear element 5.3 engage with the clamping element 5.2. Since the clamping element 5.2 cannot follow the rotational movement due to its contact with the housing, the gear element 5.3 is blocked. Consequently, the driver 5.4 rotates relative to the blocked gear element 5.3, deforming 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 in Fig. The embodiment shown in Figure 5 comprises a baffle 5.8 through which a belt 5.5, designed as a force-limiting element, can be drawn. The belt 5.5 is connected to a driver 5.4, which in its initial state does not rotate with the belt shaft 2 and / or the first force-limiting device 4.

[0028] The second force limiting device of the Fig. 5 also features a coupling ring 5.7 and pawls 5.6. In its initial state, the coupling ring 5.7 is rotationally fixed to the wheel element 5.3. For this purpose, the coupling ring 5.7 is placed on pins 5.3.1 on the wheel element 5.3 (see figure). Fig. 6) The coupling ring 5.7 is rotationally fixed 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] If the wheel element 5.3 is now connected by the clamping element 5.2 (similar to the embodiment of the Fig. 2) If blocked, the pins 5.3.1 break off 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 causes the pawls 5.6 to engage with projections 5.3.2 on the wheel element 5.3, with the pawls 5.6 protruding beyond the outer circumference of the coupling ring 5.7 and engaging in a positive locking mechanism on the inside of the driver 5.4. In this state, the driver 5.4 rotates with the coupling ring 5.6 (5.7), thereby drawing the belt 5.5 through the baffle 5.8. Thus, in this state, a force-limited relative rotation of the belt shaft occurs with the involvement of the second force-limiting device 5.

[0030] In Fig.Figure 7 schematically and exemplarily shows four force limitation levels 7.1, 7.2, 7.3, and 7.4, which are adjustable with a belt retractor according to the invention. The first force limitation level 7.1 can be set by means of the multi-stage first force limitation device 4 by involving both torsion bars 4.1 and 4.2 in the force-limited relative rotation. If one of the torsion bars 4.1 or 4.2 is decoupled by means of a switching device, the second force limitation level 7.2 is reached. If the second force limitation device 5 is coupled, the two force limitation levels achievable by the first force limitation device 4 can be increased so that the third force limitation level 7.3 and the fourth force limitation level 7.4 are adjustable. Thus, during the force-limited relative rotation of the third force limitation level 7.3, both torsion bars 4.1 and 4.2 are involved.2 of the first force limiting device 4 and the second force limiting device 5 are involved, while in the 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 and the second force limiting device 5 are involved. The four force limiting levels can be set at different times or at the beginning of the relative rotation. Reference symbol list 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 second force limiting device 5.1 pyrotechnic propulsion 5.2 Clamping element 5.3 Wheel element 5.3.1 Pen 5.3.2 Lead 5.4 Drive unit 5.5 Force limiting element 5.6 Locking pawl 5.7 Coupling ring 5.8 Harassment 6 cases 7.1 First force limitation level 7.2 Second force limitation level 7.3 Third force limitation level 7.4 fourth force limitation level

Claims

[1] Belt retractor for a motor vehicle seat belt, with - a belt shaft (2) rotatably mounted in a housing frame (1), - a profile head (3) that can be locked against the housing frame (1), - a multi-stage first force limiting device (4), wherein the first force limiting device (4) can be coupled to the profile head (3) on one side and to the belt shaft (2) on the other, and wherein the first force limiting device (4) enables a force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3), and - at least a second force limiting device (5), wherein in an initial initial state the second force limiting device (5) is decoupled and is not directly or indirectly connected to the belt shaft (2), so that without a deliberate activation of the second force limiting device (5) the force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3) takes place without force-limited participation of the second force limiting device (5), characterized by , that the second force limiting device (5) comprises at least one band that deforms during force limiting as a force limiting element (5.5). [2] 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 a coupled state the force-limited relative rotation of the belt shaft (2) relative to the locked profile head (3) takes place with force-limited participation of the second force limiting device (5). [3] Belt retractor according to claim 1 or 2, wherein the second force limiting device (5) comprises a pyrotechnic drive (5.1) by means of which a transition of the belt retractor from the initial state to a coupled state can be triggered. [4] Belt retractor according to one of the preceding claims, wherein the second force limiting device (5) comprises a driveable clamping element (5.2). [5] Belt retractor according to one of the preceding claims, 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 which is blocked in its rotation in a coupled state. [6] Belt retractor according to one of the preceding claims, wherein a driver (5.4) which drives a force limiting element in the coupled state rotates with the belt shaft (2) and / or the first force limiting device (4) in the initial state. [7] Belt retractor according to one of claims 1 to 5, 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] Belt retractor according to claim 7, wherein the driver (5.4) can be coupled to the belt shaft (2) by means of locking pawls (5.6), [9] Belt retractor according to claim 8, wherein the pawls (5.6) are mounted on a coupling ring (5.7) which rotates with the belt shaft (2) and is connected to a wheel element (5.3) in the initial state. [10] Belt retractor according to one of the preceding claims, 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). [11] Belt retractor according to one of the preceding claims, wherein a pyrotechnic drive of the first force limiting device (4) and a pyrotechnic drive of the second force limiting device (5) are arranged in separate housings (6).

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