Belt retractor comprising a force limitation device

Abstract

The invention relates to a belt retractor for a seat belt of a motor vehicle, having a belt shaft (1), a first force limitation device (2), wherein the first force limitation device (2) comprises a force limitation element (3.1, 3. 2), a driver (4), a coupling element (5) and a locking unit (6) having at least one locking element (6.1), wherein, in a force-limiting state of the first force limitation device (2), the driver (4) is connected for conjoint rotation to the coupling element (5) via the at least one locking element (6.1), and the at least one force limitation element (6.1) is fixed at one end against rotation with the belt shaft (1) and is deformed due to the rotary movement of the driver (4), wherein the at least one locking element (6.1) can be deflected radially by a relative movement between the coupling element (5) and the driver (4) to bring about the force-limiting state, wherein the at least one locking element (6.1) in a deflected position connects the driver (4) to the coupling element (5) for conjoint rotation.

Description

[0001] Belt retractor with force limiting device

[0002] The present invention relates to a belt retractor for a motor vehicle seat belt, comprising a belt shaft mounted in a housing frame for rotation about a rotational axis, and at least one first force-limiting device. The first force-limiting device comprises, in particular, 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.

[0003] During normal use of the belt retractor in a motor vehicle, the seat belt is wound onto or off the belt shaft when it is put on or taken off, with the belt shaft rotating around the (virtual) axis of rotation. During this normal use, no force limiting device is involved in the rotation of the belt shaft. In a critical situation triggered by severe deceleration of the motor vehicle, however, the belt can be pulled out with the deformation of at least one force limiting element, for which purpose the belt shaft is coupled to the housing frame via the at least one force limiting element involved. In order to provide several force limiting levels, several force limiting devices can be provided which are involved in the force-limited belt webbing pull-out simultaneously or sequentially.It can be provided that a (possibly second) force limiting device has several (at least two) force limiting elements, which can also be involved in the force-limited belt webbing extension simultaneously or sequentially.

[0004] In order to couple the force limiting elements to the belt shaft for force-limited belt webbing extension, triggering devices are provided which are mechanically implemented in a vehicle-sensitive or belt webbing-extension-sensitive manner or can be triggered by electronic actuation at a predetermined time.

[0005] The present invention relates to a belt retractor in which, in a force-limiting state of a first of possibly several force-limiting devices, the driver is connected in a rotationally fixed manner 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 spiral-shaped band, which is deformed by the rotation of the belt shaft in the force-limiting state of the associated force-limiting device. Preferably, exactly two force-limiting elements designed as bands are provided in the first force-limiting device, with both bands being connected to the driver at a first end and secured against rotation relative to the housing frame at their other end. The two spiral-shaped bands are arranged in one plane, with one band being arranged at least in sections between adjacent sections of the other band.

[0007] The invention particularly relates 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. The second force-limiting device also enables a 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 arranged coaxially within the belt shaft.

[0008] In a simple embodiment, the second force-limiting device comprises precisely one torsion bar, while in a preferred embodiment, the second force-limiting device comprises two or three torsion bars. A switching device can 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 activated for the force-limited relative rotation as needed or at a later time by means of the electronically triggerable triggering device.

[0009] The present invention particularly relates to the coupling of the driver of the first force-limiting device to the coupling element of the belt shaft. Thus, 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 connected in a rotationally fixed manner 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 relative 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, absorbing energy.

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

[0011] In principle, the driver could also be formed integrally with a force-limiting element. However, the driver is preferably formed as a separate component, which in particular has positive-locking configurations, via which the driver is connected to the force-limiting element, which is in particular designed as a band. A belt 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 belt retractor, the second force-limiting device also has a torsion bar as a force-limiting element.

[0012] The object of the present invention is to provide a belt retractor which couples the driver to the belt shaft in an alternative manner.

[0013] A solution to this problem is provided by the belt retractor having the features of independent claim 1, with further solutions and advantageous developments being explained in the preceding and following descriptions as well as in the subclaims. Individual features of the advantageous developments can be combined with one another in a technically expedient manner.

[0014] The object is achieved in particular by a belt retractor for a safety belt of a motor vehicle, with a belt shaft mounted in a housing frame so as to be rotatable about a rotational axis, 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 connected in a rotationally fixed manner 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 providedthat 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. In other words: The basic idea of ​​the invention is that the locking element of the locking unit is offset in the axial direction relative to the axis of rotation defined by the belt shaft in order to rotationally connect the driver to the coupling element. The driver is thus connected to the coupling element by a movement of the locking element in the radial direction. For this purpose, it can be provided that the locking element has a type of starting bevel, which deflects the locking element radially outward when the coupling element is rotatable relative to the locking unit to initiate the force-limiting state.

[0015] The locking unit comprises, in particular, a bearing section with which the locking unit is mounted on 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.

[0016] The at least one locking element is connected to the bearing section in such a way that the locking element is, in particular, elastically deflectable relative to the bearing section. The locking element is thus spaced 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, particularly in the radial direction.

[0017] In this case, it can be provided in particular that the at least one blocking element is attached to the bearing section by means of an arm, wherein the respective arm preferably extends along the circumferential direction of the annular bearing section, in particular with an incline from the outside to the inside. In this case, the arm describes a spiral path, wherein the length of the arm (from the in particular annular bearing section to the blocking element) is greater, in particular at least three or five times, but not more than fifteen or not more than ten times as great as the distance from the bearing section to the blocking element. In order to bring about the force-limiting state of the first force-limiting device, in particular the entire arm with the blocking element at its first end is deflected.

[0018] Particularly when forming an annular bearing section, the at least one arm and the bearing section define a plane, wherein the at least one locking element protrudes at least partially from the plane formed by the bearing section and the arm(s). In this case, the bearing section and the arms can have a thickness orthogonal to the plane of no more than 2 mm, preferably no more than 1.5 or even no more than 1 mm. In order for the locking element to have sufficient strength for engagement between the coupling element and the driver, the locking element can be reinforced by bending a free end of the locking unit onto itself. It is thus possible for a large part 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 force-limited belt extension, which can simplify installation.

[0019] Preferably, the at least one locking element, the at least one arm and the bearing section are formed in one piece.

[0020] In a further embodiment, the locking unit comprises a plurality of locking elements, wherein the plurality of locking elements and the bearing section, as well as any arms connecting the locking elements to the bearing section, are formed in one piece. The formation of a plurality of locking elements creates a particularly rotationally rigid connection between the coupling element and the driver. In particular, the coupling element has a run-on bevel for each locking element, so that each locking element is individually deflected radially by a run-on bevel when the force-limiting state is brought about.

[0021] In one embodiment, the first force-limiting device comprises a triggering device, in particular electronically triggerable and preferably having a pyrotechnic drive, 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, in particular, relative to the initially stationary driver.

[0022] In one embodiment, the first force-limiting device comprises a (toothed) wheel element on which the locking unit is mounted. The wheel element has outwardly projecting teeth, in particular on its outer circumference, wherein the triggering device is designed and arranged in such a way that an element of the triggering device can interact with the teeth of the wheel element.

[0023] The wheel element is particularly designed and arranged such that, in the initial state, it is connected to the belt shaft in a rotationally fixed manner, so that, in the initial state, the locking unit can be rotated together with the wheel element and the belt shaft. The triggering device for triggering the transfer can fix the wheel element and thus the locking unit relative to the housing frame. The triggering device can therefore stop an initial rotation of the wheel element and thus of the locking unit relative to the housing frame.

[0024] The wheel element is at least indirectly connected to the belt shaft, in particular by means of a first predetermined breaking point, the wheel element being destroyed at the predetermined breaking point when the wheel element is secured by the release device. The wheel element is thus connected to the belt shaft in such a way that the rotationally fixed connection between the wheel element and the belt shaft, which exists in the initial state, is released by the further relative rotation of the belt shaft with respect to the secured wheel element. During the subsequent relative rotation of the coupling element with respect to the secured wheel element and the thus also secured locking element, the at least one locking element is radially deflected towards the driver. As soon as 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 continued rotation of the belt shaft.The at least one locking element of the locking unit is arranged in such a way that, when the wheel element is locked, it is radially deflected by the coupling element rotating with the belt shaft and comes into engagement with the driver.

[0025] In order to enable 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, in particular, annular bearing section, form-fitting configurations which interact with a second predetermined breaking configuration formed on the wheel element, such that the second predetermined breaking configuration is destroyed and the locking unit is thus rotatable relative to the fixed wheel element with the belt shaft. The locking unit is therefore preferably designed and connected to the wheel element, in particular initially via the second predetermined breaking configuration, such that the rotationally fixed connection of the locking unit to the wheel element, which exists in the initial state, is released by the relative rotation of the locking unit relative to the wheel element following engagement of the locking element with the driver.

[0026] In one embodiment, the wheel element is cup-shaped, so that the wheel element forms a receptacle for the locking unit, wherein the locking unit is arranged for the most part within this receptacle, wherein only the locking elements protrude at least partially beyond the receptacle and thus beyond the wheel element outwards (in the axial direction), wherein the locking elements are arranged with their protruding portion between the driver (in particular radially outward) and the coupling element (in particular radially inward). This makes it possible to assemble the wheel element and the locking unit as a preassembled unit, which simplifies assembly.

[0027] The first force-limiting device comprises, in particular, a housing in which, in particular, the triggering device can be installed. The housing also comprises a particularly circular receptacle into which the wheel element with the locking unit and the force-limiting elements can be inserted. The receptacle has stop configurations on its outer circumference for the ends of the force-limiting elements, which are formed, in particular, by spiral-shaped bands. The first force-limiting unit can thus be pre-assembled and placed on the belt shaft, with the coupling element optionally being placed on the belt shaft beforehand.

[0028] The invention and the technical environment are explained below using the figures as examples. They show schematically

[0029] The invention and the technical environment are explained below using the figures as examples. They show schematically

[0030] Figure 1: an exploded view of a first force limiting device and a belt shaft of a belt retractor,

[0031] Figure 2: a housing of the first force limiting device,

[0032] Figure 3 : a locking unit of the first force limiting device,

[0033] Figure 4: a wheel element of the first force limiting device,

[0034] Figure 5 : a driver of the first force limiting device,

[0035] Figure 6: a coupling element of the first force limiting device,

[0036] Figure 7: a first force limiting element of the first force limiting device,

[0037] Figure 8 : a side view of the first force limiting device without the wheel element,

[0038] Figure 9: a first detailed view of a locking element between the driver and the coupling element,

[0039] Figure 10: a detailed view of a predetermined breaking design on the wheel element and

[0040] Figure 11 shows a further embodiment of a locking unit. The belt retractor, at least partially shown in Figure 1, comprises a belt shaft 1 for winding a safety belt (not shown).

[0041] The belt retractor also comprises a first force limiting device 2. The first force limiting device 2 has two force limiting elements 3.1, 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 Figure 7), and the driver (see also Figure 4) are 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 Figure 8). With their other end, the band-shaped force limiting elements 3.1 and 3.2 are arranged in corresponding recesses in the driver 4.

[0042] The first force limiting device 2 also comprises a coupling element 5, which is connected in a rotationally fixed manner to the belt shaft 1. The coupling element 5 has run-on bevels on its outer circumference (see in particular Figure 6).

[0043] The first force-limiting device also comprises a wheel element 7 (see Figure 4) and a locking unit 6 (see Figure 3). The locking unit 6 has an approximately circular bearing section 6.2, to which inwardly extending arms 6.3 are connected. 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 protrude (obliquely rearward in Figure 3).

[0044] The wheel element 7 has first predetermined breaking formations 7.1 in a central region, by means of which the wheel element 7 is at least indirectly connected in a rotationally fixed manner to the belt shaft 1 in an initial state. The wheel element 7 has a tooth-shaped configuration on its outer circumference and is cup-shaped between the outer circumference and the inner receptacle with the first predetermined breaking formations 7.1. In the assembled state, the locking unit 6 is arranged in this cup-shaped receptacle, with the locking elements 6.1 protruding beyond the receptacle in sections. The locking unit 6 is initially fixed in a rotationally fixed manner in the wheel element 7 by means of second predetermined breaking formations 7.2, as is also shown in detail in Figure 10.

[0045] In the assembled state, the locking elements 6.1, which protrude beyond the receptacle of the wheel element 7, are arranged between the coupling element 5 and the driver 4. Each locking element 6.1 is assigned a starting bevel of the coupling element 5 (see Figure 8).

[0046] In the initial state of the first force limiting device 2 shown in Figure 8, the wheel element 7 (not shown in Figure 8) is connected to the belt shaft 1 by means of the first predetermined breaking point 7.1, so that the locking unit 6 connected to the wheel element 7 via the second predetermined breaking point 7.2 also rotates with the belt shaft 1. In contrast, the driver 4 and the

[0047] Force limiting elements 3.1 and 3.2 are arranged stationary in the housing 10 in the initial state. By triggering the triggering device 8, the relative rotation of the wheel element 7 can be stopped by bringing a blocking element 8.1 into engagement with the tooth design on the outer circumference of the wheel element 7.

[0048] Since 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 thus also the coupling element 5 continue to rotate relative to the fixed wheel element 7 and the locking unit 6, which is fixed together with the wheel element 7.

[0049] The relative rotation of the coupling element 5 relative to the radially deflectable locking elements 6.1 results in a relative movement of the locking elements 6.1 along the run-on slopes of the coupling element 5. The locking elements 6.1 are thus deflected radially outward until they engage with the driver 4. A rotationally fixed connection is thus established between the coupling element 5 and the driver 4 via the locking elements 6.1, so that with continued rotation of the belt shaft 1 and the coupling element 5, the driver 4 is also driven in a rotational movement.

[0050] Subsequently, the locking unit 6 with the driver 4 and the coupling element 5 also rotates, whereby the connection of the locking unit 6 with the wheel element 7 at the second predetermined breaking point 7.2 is destroyed, so that the locking unit 6 subsequently rotates relative to the fixed wheel element 7.

[0051] 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, whereby energy is absorbed and thus a force limiting level is provided for the relative rotation of the belt shaft 1.

[0052] Due to the arrangement of the locking elements 6.1 on the arms 6.3 and the design of the locking elements 6.1 protruding 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.

[0053] The embodiment of the locking unit 6 shown in Figure 11 has, in comparison to the embodiment of Figure 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 back on itself. List of reference symbols Belt shaft First force limiting device First force limiting element Second force limiting element Driver Coupling element Locking unit Locking element Bearing section Arm Wheel element First predetermined breaking point Second predetermined breaking point Triggering device Blocking element Second force limiting device Housing Distance Thickness

Claims

Claims 1. Belt retractor for a safety belt of a motor vehicle, with a belt shaft (1) mounted in a housing frame so as to be rotatable 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 • comprises a locking unit (6) having at least one locking element (6.1), wherein in a force-limiting state of the first force-limiting device (2) • the driver (4) is connected to the coupling element (5) via the at least one locking element (6.1) in a rotationally fixed manner, 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), characterized in that the at least one locking element (6.1) is radially deflectable by a relative movement between the coupling element (5) and the driver (4) to bring about the force-limiting state, 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.

2. Belt retractor according to claim 1, wherein the locking unit (6) has a particularly annular bearing section (6.2), relative to which the at least one locking element (6.1) is deflectable.

3. Belt retractor according to claim 2, wherein the at least one locking element (6.1) is attached to the bearing section (6.2) by means of an arm (6.3), the bearing section (6.2) and the at least one arm (6.3) defining a plane from which the at least one locking element (6.1) protrudes.

4. Belt retractor according to one of the preceding claims, wherein the locking unit (6) has a plurality of locking elements (6.1) which are in particular formed integrally with the bearing section (6.2).

5. 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).

6. Belt retractor according to one of the preceding claims, wherein the first force limiting device (2) has a triggering device (8) for triggering a transfer of the first force limiting device (2) from an initial state to the force-limiting state.

7. 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.

8. Belt retractor according to claim 6 and 7, wherein in the initial state the wheel element (7) is connected in a rotationally fixed manner to the belt shaft (1), so that the locking unit (6) is rotatable together with the wheel element (7) with the belt shaft (1), wherein the triggering device (8) for Triggering the transfer fixes the wheel element (7) and thus the locking unit (6) relative to the housing frame.

9. Belt retractor according to claim 8, wherein the wheel element 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) existing in the initial state is released by the further relative rotation of the belt shaft (1) with respect to the fixed wheel element (7).

10. Belt retractor according to claim 8 or 9, wherein the at least one locking element (6.1) is arranged such that the at least one locking element (6.1) is radially deflected by the coupling element (5) rotating with the belt shaft (1) when the wheel element (7) is fixed and comes into engagement with the driver (4). 1 1. Belt retractor according to claim 10, 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) to 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) occurring after the engagement of the locking element (6.1) with the driver (4).

12. Belt retractor according to one of the preceding claims, wherein the belt retractor comprises a profile head which can be locked relative to the housing frame and a particularly multi-stage second force limiting device (9), wherein the second force limiting device can be coupled on the one hand to the profile head and on the other hand to the belt shaft (1) and wherein the second force limiting device (2) enables a force-limited relative rotation of the belt shaft relative to the locked profile head.

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