Seatbelt retractor with force limiting device

Abstract

Seatbelt retractor for a motor vehicle seatbelt, with - a belt shaft (1) rotatably mounted in a housing frame about an axis of rotation, - at least one first force limiting device (2), wherein the first force limiting device (2) • at least one force limiting element (3.1, 3.2), • a driver (4) connected to the at least one force limiting element (3.1, 3.2), • a coupling element (5) rotating with the belt shaft and • comprising a locking unit (6) comprising at least one locking element (6.1), wherein in a force-limiting state the first force-limiting device (2) • the driver (4) is connected to the coupling element (5) in a rotationally fixed manner via the at least one locking element (6.1), so that the driver (4) rotates with the belt shaft (1), and • the at least one force limiting element (6.1) is fixed at one end against rotation with the belt shaft (1) and is deformed due to the rotational movement of the driver (4), wherein the at least one locking element (6.1) is radially deflectable to bring about the force limiting state by a relative movement between the coupling element (5) and the driver (4), wherein the at least one locking element (6.1) in a deflected position connects the driver (4) to the coupling element (5) in a rotationally fixed manner, characterized in that the locking unit (6) has a bearing section (6.2) and several locking elements (6.1) formed integrally with the bearing section (6.2), wherein the several locking elements (6.1) are deflectable relative to the bearing section (6.2).

Description

[0001] The present invention relates to a belt retractor for a motor vehicle seat belt, comprising a belt shaft rotatably mounted about an axis of rotation in a housing frame and at least one first force limiting device. The first force limiting device particularly includes at least one force limiting element, a driver connected to the at least one force limiting element, a coupling element rotating with the belt shaft, and a locking unit comprising at least one locking element.

[0002] During normal use of the seatbelt retractor in a motor vehicle, the seatbelt is wound onto and unwound from the belt shaft when being fastened and unfastened, with the belt shaft rotating around its (virtual) axis of rotation. In this normal use, no force-limiting device is involved in the rotation of the belt shaft. However, in a critical situation triggered by strong deceleration of the vehicle, the seatbelt can extend, deforming at least one force-limiting element. For this to occur, the belt shaft is coupled to the housing frame via the at least one force-limiting element involved.

[0003] To provide multiple force limitation levels, several force limitation devices can be provided, which participate in the force-limited webbing extension simultaneously or sequentially. It can be provided that one (or possibly a second) force limitation device has several (at least two) force limitation elements, which can also participate in the force-limited webbing extension simultaneously or sequentially.

[0004] To couple the force limiting elements with the belt shaft for force-limited belt extension, release devices are provided which are mechanically implemented in a vehicle-sensitive or belt extension-sensitive manner, or which can be triggered electronically at a predetermined time.

[0005] The present invention relates to a belt retractor in which, in a force-limiting state of a first of optionally several force-limiting devices, the driver is rotationally fixed to the coupling element via the at least one locking element, so that the driver rotates with the belt shaft and the at least one force-limiting element is fixed at one end against rotation with the belt shaft and is deformed due to the rotational movement of the driver.

[0006] The force-limiting element is, in particular, a spirally shaped band which, in the force-limiting state of the associated force-limiting device, is deformed by the rotation of the belt shaft. Preferably, exactly two force-limiting elements designed as bands are provided in the first force-limiting device, wherein both bands are connected to the driver at one end and are fixed at their other end against rotation relative to the housing frame. The two spirally shaped bands are arranged in one plane, with one band being arranged at least partially between adjacent sections of the other band.

[0007] The invention relates in particular to belt retractors in which, in addition to the first force limiting device, a second, in particular multi-stage, force limiting device is provided, which can be coupled on the one hand to a profile head that can be locked relative to the housing frame and on the other hand to the belt shaft, wherein the second force limiting device also allows force-limited relative rotation of the belt shaft relative to the locked profile head. The force limiting elements of the second force limiting device are in particular torsion bars which are arranged coaxially within the belt shaft.

[0008] In a simple embodiment, the second force-limiting device comprises exactly one torsion bar, while in a preferred embodiment, the second force-limiting device comprises two or three torsion bars, and a switching device may be provided to control which of the torsion bars participates in the force-limited relative rotation of the belt shaft. The belt retractor is particularly configured such that, for an initial force-limited relative rotation, the belt shaft is coupled to the housing frame by means of the second force-limiting device, while the first force-limiting device is engaged for the force-limited relative rotation as needed or at a later time by means of the electronically triggerable release device.

[0009] The present invention relates in particular to the coupling of the driver of the first force-limiting device with the coupling element of the belt shaft. In an initial state of the first force-limiting device, the belt shaft can rotate freely relative to the driver. To enable the first force-limiting device to participate in the force-limited relative rotation, the coupling element, which is rotationally fixed to the belt shaft, is connected to the driver by means of the locking element of the locking unit. During the subsequent relative rotation of the belt shaft with respect to the housing frame, the driver rotates with the belt shaft, whereby the at least one force-limiting element connected to the driver is deformed under energy absorption.

[0010] The coupling element can, for example, be integrally connected to the belt shaft. However, it is preferred that the coupling element be provided as a separate component, which is at least indirectly connected to the belt shaft. The coupling element can, for example, be mounted on a projection on the belt shaft in a rotationally fixed manner.

[0011] The driver could, in principle, be formed as a single component within a force-limiting element. However, it is preferably designed as a separate component, which in particular features positive locking mechanisms by which the driver is connected to the force-limiting element, which is primarily designed as a band.

[0012] A seatbelt retractor with a first force limiting device and a second force limiting device is known, for example, from WO 2020 / 021 003 A1. In this seatbelt retractor, the second force limiting device also has a torsion bar as a force limiting element. A seatbelt retractor with the features of the preamble of claim 1 is known from DE 10 2009 033 669 A1. Another seatbelt retractor is known from DE 10 2011 087 413 A1.

[0013] The object of the present invention is to provide a belt retractor that couples the drive unit to the belt shaft in an alternative manner.

[0014] One solution to this problem is given by the belt retractor with the features of independent claim 1, with further solutions and advantageous embodiments explained in the preceding and following description as well as in the dependent claims. Individual features of the advantageous embodiments can be combined with one another in a technically meaningful manner.

[0015] The problem is solved in particular by a belt retractor for a motor vehicle seat belt, with a belt shaft rotatably mounted about an axis of rotation in a housing frame, at least one first force limiting device, wherein the first force limiting device comprises at least one force limiting element, a driver connected to the at least one force limiting element, a coupling element rotating with the belt shaft, and a locking unit having at least one locking element, wherein in a force-limiting state of the first force limiting device, the driver is rotationally fixed to the coupling element via the at least one locking element, so that the driver rotates with the belt shaft and the at least one force limiting element is fixed at one end against rotation with the belt shaft and is deformed due to the rotational movement of the driver, wherein it is provided thatthat the at least one locking element is radially deflectable to bring about the force-limiting state by a relative movement between the coupling element and the driver, wherein the at least one locking element in a deflected position connects the driver to the coupling element in a rotationally fixed manner.

[0016] In other words, the basic concept of the invention provides that the locking element of the locking unit is offset axially relative to the axis of rotation defined by the belt shaft to connect the driver to the coupling element in a rotationally fixed manner. The connection of the driver to the coupling element is thus achieved by a radial movement of the locking element. For this purpose, the locking element may have a chamfer that deflects the locking element radially outwards when the coupling element is rotatable relative to the locking unit to initiate the force-limiting state.

[0017] The locking unit comprises, in particular, a bearing section by which the locking unit is mounted to another component of the belt retractor. The bearing section is, in particular, ring-shaped, so that the locking unit can be connected to the other component of the belt retractor at several points.

[0018] The at least one locking element is connected to the bearing section in such a way that the locking element is elastically deflectable relative to the bearing section. The locking element is therefore spaced apart from the bearing section, with the distance being at least 1 mm or preferably at least 2 mm, but particularly preferably not more than 2.5 mm, especially in the radial direction.

[0019] In this context, it can be provided that the at least one locking element is attached to the bearing section by means of an arm, the respective arm preferably extending along the circumferential direction of the annular bearing section, in particular with a slope from the outside to the inside. In this case, the arm describes a spiral path, the length of the arm (from the bearing section, in particular the annular section, to the locking element) being greater, in particular at least three or five times, but not more than fifteen or not more than ten times, than the distance from the bearing section to the locking element. To bring about the force-limiting state of the first force-limiting device, the entire arm with the locking element at its first end is thus deflected.

[0020] Particularly when forming an annular bearing section, the at least one arm and the bearing section define a plane, with the at least one locking element projecting at least partially from the plane formed by the bearing section and the arm(s). The bearing section and the arms can have a thickness of no more than 2 mm, preferably no more than 1.5 mm, or even no more than 1 mm, perpendicular to this plane. To ensure that the locking element has sufficient strength to engage between the coupling element and the driver, the locking element can be reinforced by bending a free end of the locking unit over itself. Thus, it is possible for a large portion of the locking unit to be offset from the plane in which the coupling element with the driver is arranged to bring about the force-limiting state of the first force-limiting device.This allows the locking unit to be positioned offset from the plane in which the driver rotates during the force-limited belt extension, which can simplify assembly.

[0021] Preferably, the at least one locking element, the at least one arm and the bearing section are formed in one piece.

[0022] In a further embodiment, the locking unit comprises several locking elements, wherein the multiple locking elements and the bearing section, as well as optionally the arms connecting the locking elements to the bearing section, are formed as a single unit. The formation of multiple locking elements creates a particularly rotationally rigid connection between the coupling element and the driver. In particular, the coupling element has a chamfer for each locking element, so that each locking element is individually deflected radially by its chamfer when the force-limiting state is brought about.

[0023] In one embodiment, the first force limiting device has a release mechanism, preferably electronically triggered and with a pyrotechnic actuator, for triggering a transition of the first force limiting device from an initial state to the force-limiting state. In the initial state, the belt shaft is rotatably mounted, particularly relative to the initially stationary driver.

[0024] In one embodiment, the first force limiting device comprises a (gear) wheel element on which the locking unit is mounted. The wheel element has, in particular, outwardly projecting teeth on its outer circumference, and the release device is designed and arranged such that an element of the release device can interact with the teeth of the wheel element.

[0025] The wheel element is designed and arranged in such a way that, in its initial state, it is rotationally fixed to the belt shaft, allowing the locking unit and the wheel element to rotate freely with the belt shaft. The release mechanism for initiating the transfer can lock the wheel element, and thus the locking unit, relative to the housing frame. Therefore, the release mechanism can stop any initial rotation of the wheel element, and thus of the locking unit, relative to the housing frame.

[0026] The wheel element is connected to the belt shaft, at least indirectly, by means of a first predetermined breaking point. The wheel element is destroyed at this predetermined breaking point when it is locked in place by the release mechanism. Thus, the wheel element is connected to the belt shaft in such a way that the rotationally fixed connection between the wheel element and the belt shaft, present in the initial state, is released by the further relative rotation of the belt shaft with respect to the locked wheel element. During the subsequent relative rotation of the coupling element with respect to the locked wheel element and the locking element, the radial deflection of at least one locking element towards the drive lug occurs.

[0027] Once the locking element has connected the coupling element to the driver in a rotationally fixed manner, the locking element is also carried along by the further rotation of the belt shaft. The at least one locking element of the locking unit is therefore arranged such that, when the wheel element is locked, it is deflected radially by the coupling element rotating with the belt shaft and engages with the driver.

[0028] To allow the at least one locking element to rotate with the driver and the coupling element during further rotation of the belt shaft, the locking unit has, in particular on an outer circumference of the bearing section, which is preferably annular, positive locking features that interact with a second predetermined breaking feature formed on the wheel element, such that the second predetermined breaking feature is destroyed, thus allowing the locking unit to rotate relative to the fixed wheel element and the belt shaft. The locking unit is therefore preferably designed and initially connected to the wheel element via the second predetermined breaking feature such that the rotationally fixed connection of the locking unit to the wheel element present in the initial state is released by the relative rotation of the locking unit relative to the wheel element after the locking element engages with the driver.

[0029] In one embodiment, the wheel element is cup-shaped, forming a receptacle for the locking unit. The locking unit is located largely within this receptacle, with only the locking elements projecting outwards (in the axial direction) at least partially beyond the receptacle and thus beyond the wheel element. The protruding portion of the locking elements is positioned between the drive element (particularly radially outwards) and the coupling element (particularly radially inwards). This allows the wheel element and the locking unit to be assembled as a pre-assembled unit, thus simplifying assembly.

[0030] The first force limiting device comprises, in particular, a housing in which the release mechanism may be installed. The housing also has a receptacle, in particular circular, into which the wheel element with the locking unit and the force limiting elements can be inserted. The receptacle has stop designs on its outer circumference for the ends of the force limiting elements, which are formed, in particular, by spiral bands. The first force limiting unit can thus be pre-assembled and mounted onto the belt shaft, with the coupling element optionally being mounted onto the belt shaft beforehand.

[0031] The invention and its technical context are explained below using the figures as examples. They show schematic representations.

[0032] The invention and its technical context are explained below using the figures as examples. They show schematic representations. Fig. 1: An exploded view of a first force limiting device and a belt shaft of a belt retractor, Fig. 2: a housing of the first force limiting device, Fig. 3: a locking unit of the first force limiting device, Fig. 4: a wheel element of the first force limiting device, Fig. 5: a driver of the first force limiting device, Fig. 6: a coupling element of the first force limiting device, Fig. 7: a first force limiting element of the first force limiting device, Fig. 8: A side view of the first force limiting device without the wheel element, Fig. 9: A first detailed view of a locking element between the driver and the coupling element, Fig. 10: a detailed view of a predetermined breaking point design on the wheel element and Fig. 11: another embodiment of a locking unit.

[0033] The in Fig. 1 The belt retractor, at least partially shown, comprises a belt shaft 1 for winding up a safety belt (not shown).

[0034] The belt retractor also includes a first force limiting device 2. The first force limiting device 2 has two force limiting elements 3.1 and 3.2 and a driver 4 connected to the two force limiting elements 3.1 and 3.2. In the assembled state, the force limiting elements 3.1 and 3.2, which are formed as bands and are spirally shaped (see also Fig. 7) and the driver (see also Fig. 4) arranged within a receptacle of a housing 10 of the first force limiting unit 2. The free, outer end of the force limiting elements 3.1 and 3.2 rests against a stop design in the receptacle (see in particular ). Fig. 8) At their other end, the band-shaped force limiting elements 3.1 and 3.2 are arranged in corresponding recesses in the driver 4.

[0035] The first force limiting device 2 also includes a coupling element 5, which is rotationally fixed to the belt shaft 1. The coupling element 5 has chamfers on its outer circumference (see in particular the figure). Fig. 6).

[0036] The first force limiting device also includes a wheel element 7 (see Fig. 4) and a locking unit 6 (see Fig. 3) The locking unit 6 has an approximately circular bearing section 6.2, to which inwardly extending arms 6.3 are attached. Locking elements 6.1 are formed at the free ends of the arms 6.3. The bearing section 6.2 and the arms 6.3 define a plane from which the locking elements 6.1 (in Fig. protrude diagonally to the rear (3).

[0037] The wheel element 7 has first predetermined breaking features 7.1 in a central area, by means of which the wheel element 7 is at least indirectly rotationally fixed to the belt shaft 1 in an initial state. The wheel element 7 has a tooth-like shape on its outer circumference and is cup-shaped between the outer circumference and the inner receptacle with the first predetermined breaking features 7.1. In the assembled state, the locking unit 6 is arranged in this cup-shaped receptacle, with the locking elements 6.1 projecting section by section beyond the receptacle. The locking unit 6 is initially rotationally fixed in the wheel element 7 by means of second predetermined breaking features 7.2, as is also the case in Fig. 10 is shown in detail.

[0038] In the assembled state, the locking elements 6.1, which protrude beyond the mounting of the wheel element 7, are arranged between the coupling element 5 and the driver 4. Each locking element 6.1 is associated with a chamfer on the coupling element 5 (see Fig. 8).

[0039] In the Fig. The initial state of the first force limiting device 2 shown in section 8 is the (in Fig. The wheel element 7 (not shown) is connected to the belt shaft 1 by means of the first predetermined breaking feature 7.1, so that the locking unit 6, which is connected to the wheel element 7 via the second predetermined breaking feature 7.2, also rotates with the belt shaft 1. In contrast, the driver 4 and the force limiting elements 3.1 and 3.2 connected to the driver 4 are fixed in position in the housing 10 in the initial state. By triggering the release device 8, the relative rotation of the wheel element 7 can be stopped by engaging a locking element 8.1 with the tooth design on the outer circumference of the wheel element 7.

[0040] As the belt shaft 1 continues to rotate relative to the fixed wheel element 7, the connection between the wheel element 7 and the belt shaft 1 is destroyed at the first predetermined breaking point 7.1. The belt shaft 1, and therefore also the coupling element 5, continues to rotate relative to the fixed wheel element 7 and the locking unit 6 fixed together with the wheel element 7.

[0041] The relative rotation of the coupling element 5 with respect to the radially deflectable locking elements 6.1 causes a relative movement of the locking elements 6.1 along the approach ramps of the coupling element 5. This deflects the locking elements 6.1 radially outwards until they engage with the driver 4. The locking elements 6.1 thus establish a rotationally fixed connection between the coupling element 5 and the driver 4, so that with continued rotation of the belt shaft 1 and the coupling element 5, the driver 4 is also driven into a rotary motion.

[0042] Subsequently, the locking unit 6 also rotates with the driver 4 and the coupling element 5, thereby destroying the connection of the locking unit 6 with the wheel element 7 at the second predetermined breaking point 7.2, so that the locking unit 6 subsequently rotates relative to the fixed wheel element 7.

[0043] At the same time, due to the rotational movement of the driver 4, the two force limiting elements 3.1 and 3.2 are deformed, thereby absorbing energy and providing a force limiting level for the relative rotation of the belt shaft 1.

[0044] By arranging the locking elements 6.1 on the arms 6.3 and by the design of the locking elements 6.1 projecting from the wheel element 7, the locking unit 6 can be arranged offset from the plane in which the force limitation takes place by deformation of the force limiting elements 3.1 and 3.2.

[0045] The in Fig. The embodiment of the locking unit 6 shown in 11 differs from the embodiment of the Fig.3 a smaller thickness 12 orthogonal to the plane formed by the bearing section 6.2 and the arms 6.3. The thickness of the bearing section 6.2 and the arms 6.3 is, in particular, 1 mm. In order for the locking elements 6.1 to have sufficient strength, the starting material forming the locking unit 6 is bent over itself. Reference symbol list 1 belt shaft 2 first force limiting device 3.1 First force limiting element 3.2 Second force limiting element 4 drive wheels 5 coupling element 6 locking unit 6.1 Locking element 6.2 Storage section 6.3 Arm 7 Wheel element 7.1 First predetermined breaking point design 7.2 Second predetermined breaking point design 8 Triggering device 8.1 Blocking element 9 second force limiting device 10 cases 11 distance 12 Thickness

Claims

[1] Belt retractor for a motor vehicle seat belt, with - a belt shaft (1) rotatably mounted in a housing frame about an axis of rotation, - at least one first force limiting device (2), wherein the first force limiting device (2) • at least one force limiting element (3.1, 3.2), • a driver (4) connected to the at least one force limiting element (3.1, 3.2), • a coupling element (5) rotating with the belt shaft and • comprising a locking unit (6) comprising at least one locking element (6.1), wherein in a force-limiting state the first force-limiting device (2) • the driver (4) is connected to the coupling element (5) in a rotationally fixed manner via the at least one locking element (6.1), so that the driver (4) rotates with the belt shaft (1), and • the at least one force limiting element (6.1) is fixed at one end against rotation with the belt shaft (1) and is deformed due to the rotational movement of the driver (4), wherein the at least one locking element (6.1) is radially deflectable to bring about the force limiting state by a relative movement between the coupling element (5) and the driver (4), wherein the at least one locking element (6.1) in a deflected position connects the driver (4) to the coupling element (5) in a rotationally fixed manner, characterized by , that the locking unit (6) has a bearing section (6.2) and several locking elements (6.1) formed in one piece with the bearing section (6.2), wherein the several locking elements (6.1) are deflectable relative to the bearing section (6.2). [2] Belt winder according to claim 1, wherein the bearing section (6.2) is ring-shaped. [3] Belt winder according to claim 2, wherein the multiple locking elements (6.1) are each attached to the bearing section (6.2) by means of an arm (6.3), wherein the bearing section (6.2) and the at least one arm (6.3) define a plane from which the locking elements (6.1) protrude. [4] Belt retractor according to one of the preceding claims, wherein in the initial state the belt shaft (1) is rotatable relative to the driver (4). [5] Belt retractor according to one of the preceding claims, wherein the first force limiting device (2) has a triggering device (8) for triggering a transition of the first force limiting device (2) from an initial state to the force limiting state. [6] Belt retractor according to one of the preceding claims, wherein the first force limiting device (2) has a wheel element (7) on which the locking unit (6) is mounted. [7] Belt retractor according to claims 5 and 6, wherein in the initial state the wheel element (7) is non-rotatably connected to the belt shaft (1), so that the locking unit (6) together with the wheel element (7) is rotatable with the belt shaft (1), wherein the release device (8) for triggering the transfer fixes the wheel element (7) and thus the locking unit (6) relative to the housing frame. [8] Belt retractor according to claim 7, wherein the wheel element (7) is connected to the belt shaft (1) in such a way that the rotationally fixed connection of the wheel element (7) to the belt shaft (1) present in the initial state is released by the further relative rotation of the belt shaft (1) with respect to the fixed wheel element (7). [9] Belt retractor according to claim 7 or 8, wherein the at least one locking element (6.1) is arranged such that the at least one locking element (6.1) is deflected radially by the coupling element (5) rotating with the belt shaft (1) when the wheel element (7) is fixed and engages with the driver (4). [10] Belt retractor according to claim 9, wherein the locking unit (6) is connected to the wheel element (7) in such a way that the rotationally fixed connection of the locking unit (6) with the wheel element (7) present in the initial state is released by the relative rotation of the locking unit (6) relative to the wheel element (7) after the engagement of the locking element (6.1) with the driver (4). [11] Belt winder according to one of the preceding claims, wherein the belt winder comprises a profile head that can be locked relative to the housing frame and a second force limiting device (9), wherein the second force limiting device (9) can be coupled to the profile head on one side and to the belt shaft (1) on the other, and wherein the second force limiting device (9) enables a force-limited relative rotation of the belt shaft (1) relative to the locked profile head.

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