Belt retractor with force limiting device

Abstract

The present invention relates to a belt retractor for a seat belt of a motor vehicle, comprising a belt shaft (1) and a first force limiting device (2), the first force limiting device (2) comprising force limiting elements (3.1, 3.2), a driver (4), a connecting 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 limiting device (2), the driver (4) is rotationally connected to the connecting element (5) via the at least one locking element (6.1), the at least one force-limiting element (6.1) being fixed at one end against rotation with the belt shaft (1) and deformable by the rotational movement of the driver (4), the at least one locking element (6.1) being radially deflectable by relative movement between the connecting element (5) and the driver (4) to bring about the force-limiting state, the at least one locking element (6.1) in the deflected position connecting the driver (4) to the connecting element (5) for rotational coupling.

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 about a rotation axis, and at least one first force limiting device, which in particular 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. [Background technology]

[0002] During normal use of a belt retractor in a motor vehicle, the seat belt is wound onto or unwound from the belt shaft during donning or doffing, causing the belt shaft to rotate around a (virtual) axis of rotation. During this normal use, the force limiting device is not involved in the rotational movement of the belt shaft. However, in critical situations caused by strong deceleration of the motor vehicle, belt elongation accompanied by deformation of at least one force limiting element may occur. For this purpose, the belt shaft is connected to the housing frame via at least one involved force limiting element. To provide two or more force limiting levels, two or more force limiting devices may be provided, and the two or more force limiting devices may be simultaneously or sequentially involved in the force-limited elongation of the belt webbing. The (possibly second) force limiting device may have two or more (at least two) force limiting elements, and the two or more (at least two) force limiting elements may be simultaneously or sequentially involved in the force-limited elongation of the belt webbing.

[0003] A trigger device is provided to couple the force-limiting element to the belt shaft for force-limited belt webbing extension, and the trigger device can be mechanically implemented in a vehicle-sensing or belt webbing extension-sensing manner, or can be electronically triggered at a predetermined time. Summary of the Invention

[0004] The present invention relates to a belt retractor in which, in a force-limiting state of a first force-limiting device, possibly of two or more force-limiting devices, a driver is connected to a coupling element via at least one locking element for coupling rotation, so that the driver rotates with the belt shaft, and at least one force-limiting element is fixed at one end so as not to rotate with the belt shaft and is deformed by the rotational movement of the driver.

[0005] The force-limiting element is in particular a spiral webbing that 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 webbings are provided in the first force-limiting device, both webbings being connected at a first end to the driver and fixed at their other ends against rotation relative to the housing frame. The two spiral webbings are arranged in one plane, with one webbing being at least partially located between adjacent sections of the other webbing.

[0006] The invention relates in particular to a belt retractor which, in addition to a first force limiting device, is provided with a second, in particular multi-stage, force limiting device which can be connected on the one hand to a profile head which can be locked relative to the housing frame and on the other hand to the belt shaft, but which also allows a force-limited relative rotation of the belt shaft with respect 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.

[0007] In a simple embodiment, the second force limiting device comprises only one torsion bar, in preferred embodiments the second force limiting device comprises two or three torsion bars and a switching device can be provided by means of which switching device it is possible to control which of the torsion bars is involved in the force-limited relative rotation of the belt shaft. The belt retractor is particularly designed such that for an initial force-limited relative rotation the belt shaft is connected to the housing frame by the second force limiting device, while the first force limiting device can be switched on for force-limited relative rotation as required or at a later point in time by an electronically triggerable triggering device.

[0008] The present invention particularly relates to coupling a driver of a first force-limiting device to a coupling element of a belt shaft. In an initial state of the first force-limiting device, the belt shaft is free to rotate relative to the driver. To engage in force-limited relative rotation of the first force-limiting device, the coupling element, which is connected for coupled rotation relative to the belt shaft, is connected to the driver by a locking element of a locking unit. During subsequent relative rotation of the belt shaft relative to the housing frame, the driver rotates with the belt shaft, and at least one force-limiting element connected to the driver deforms while absorbing energy.

[0009] The connecting element may be, for example, integrally connected to the belt shaft. However, it is preferred that the connecting element is provided as a separate component, which is at least indirectly connected to the belt shaft. The connecting element may, for example, be mounted on a shoulder of the belt shaft and be able to rotate in an articulated manner.

[0010] In principle, the driver can also be formed as a single part on the force-limiting element, however preferably the driver is designed as a separate component with a particular form-fitting design, and the driver is connected via a form-fitting design to the force-limiting element, which is particularly designed as a webbing.

[0011] A known belt retractor having a first force limiting device and a second force limiting device is described in International Publication No. 2020021003(A1), for example. In this belt retractor, the second force limiting device also has a torsion bar as a force limiting element.

[0012] SUMMARY OF THE INVENTION It is an object of the present invention to provide a belt retractor that alternatively connects the driver to the belt shaft.

[0013] One solution to this object is provided by a belt retractor having the features of independent claim 1, further solutions and advantageous developments are described above and below in the description and in the dependent claims. The individual features of advantageous further developments can be combined in a technically rational manner.

[0014] To this end, a belt retractor is provided, in particular for a seat belt of a motor vehicle, comprising a belt shaft rotatably mounted on a housing frame about a rotation axis, and at least one first force limiting device, the at least one first force limiting device having at least one force limiting element, a driver connected to the at least one force limiting element, a connecting element that rotates 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 rotatably connected to the connecting 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 so as not to rotate with the belt shaft and is deformed by the rotational movement of the driver, and the at least one locking element can be radially deflected to bring about the force-limiting state by relative movement between the connecting element and the driver, and the at least one locking element in the deflected position is adapted to rotatably connect the driver to the connecting element.

[0015] In other words, the basic idea of ​​the present invention is to displace the locking element of the locking unit axially relative to the rotation axis defined by the belt shaft, thereby connecting the driver to the connecting element and rotating the driver. The driver is thus connected to the connecting element by the radial movement of the locking element. For this purpose, the locking element can have a kind of starting ramp that deflects the locking element radially outward and initiates a force-limiting state when the connecting element is rotatable relative to the locking unit.

[0016] The locking unit in particular comprises a support part for attaching the locking unit to another component of the belt retractor, the support part being in particular annular, and the locking unit can be connected to the other component of the belt retractor at two or more points.

[0017] The at least one locking element is connected to the support part in such a way that it can be deflected, in particular elastically, relative to the support part and is therefore spaced from the support part by a distance, in particular in the radial direction, of at least 1 mm, or preferably at least 2 mm, but particularly preferably not more than 2.5 mm.

[0018] In this case, it can be provided in particular that at least one locking element is attached to the support part by an arm, each arm preferably extending along the circumferential direction of the annular support part, in particular with a gradient from the outside to the inside. In this case, the arm describes a spiral path, and the length of the arm (in particular from the annular support part to the locking element) is greater than the distance from the support part to the locking element, in particular at least 3 or 5 times, but not more than 15 or 10 times, that distance. To bring about the force-limiting state of the first force-limiting device, the entire arm having the locking element at its first end is deflected.

[0019] In particular, when forming an annular support portion, at least one arm and the support portion define a plane, and at least one locking element at least partially protrudes from the plane formed by the support portion and the arm. In this case, the support portion and the arm perpendicular to the plane can have a thickness of 2 mm or less, preferably 1.5 mm or less, or even 1 mm or less. To ensure that the locking element has sufficient strength to engage between the connecting element and the driver, the locking element can be strengthened by bending the free end of the locking unit back onto itself. This allows a large portion of the locking unit to be offset from the plane in which the connecting element with the driver rotates to provide 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-limiting belt extension, thereby simplifying installation.

[0020] Preferably, the at least one locking element, the at least one arm and the support portion are integrally formed.

[0021] In a further embodiment, the locking unit has two or more locking elements, and the two or more locking elements and the support part, and, if applicable, the arms connecting the locking elements to the support part, are formed integrally. The formation of the two or more locking elements results in a particularly non-rotating connection between the connecting element and the driver. In particular, the connecting element has a start ramp for each locking element, so that each locking element is individually deflected radially by the start ramp when the force-limiting state is established.

[0022] In one embodiment, the first force-limiting device has a triggering device, in particular an electronically triggerable triggering device, preferably a pyrotechnic drive for triggering the transition of the first force-limiting device from an initial state to a force-limiting state, in which the belt shaft is mounted to be rotatable relative to an initially stationary driver.

[0023] In one embodiment, the first force limiting device comprises a (toothed) wheel element to which the locking unit is attached, the wheel element in particular having outwardly protruding teeth on its periphery, and the trigger device in particular designed and arranged so that the elements of the trigger device can interact with the teeth of the wheel element.

[0024] The wheel element is particularly designed and arranged to be connected to the belt shaft in an initial state so that the wheel element rotates in a coupled manner, and the triggering device for triggering the transition can fix the wheel element and thus the locking unit relative to the housing frame. The release device can stop the initial rotation of the wheel element and thus the locking unit relative to the housing frame.

[0025] The wheel element is at least indirectly connected to the belt shaft by a first predetermined breaking structure, in particular, and the wheel element is broken at the predetermined breaking structure when the wheel element is fixed by the release device. Thus, the wheel element is connected to the belt shaft such that the initial connection of the wheel element to the belt shaft for connecting rotation is released by further relative rotation of the belt shaft with respect to the fixed wheel element. During the subsequent relative rotation of the connecting element with respect to the fixed wheel element and therefore the fixed locking element, at least one locking element is deflected radially toward the driver.

[0026] As soon as the locking element connects the coupling element to the driver for coupling rotation, the locking element is also synchronized by further rotation of the belt shaft. At least one locking element of the locking unit is radially biased by the coupling element rotating with the belt shaft and positioned to engage with the driver when the wheel element is secured.

[0027] To allow the at least one locking element to rotate together with the driver and the coupling element during further rotation of the belt shaft, the locking unit has a form-fitting structure, particularly on the outer periphery of the annular support part, which interacts with a second predetermined breaking structure formed on the wheel element, so that the second predetermined breaking structure is broken and the locking unit is thus rotatable together with the belt shaft relative to the fixed wheel element. Therefore, the locking unit is preferably designed and connected to the wheel element, particularly initially via the second predetermined breaking structure, in such a way that the initial connection for coupling rotation of the locking unit to the wheel element is released by the relative rotation of the locking unit with respect to the wheel element that occurs after engagement of the locking element with the driver.

[0028] In one embodiment, the wheel element is pot-shaped, so that it forms a receptacle for the locking unit, which is largely located within this receptacle, with only the locking elements at least partially projecting outward (axially) beyond the receptacle and thus beyond the wheel element, with the locking elements being arranged with their projecting section between the driver (particularly radially outward) and the coupling element (particularly radially inward), which allows the wheel element and the locking unit to be assembled as a pre-assembled unit, simplifying assembly.

[0029] The first force-limiting device has a housing into which the trigger device can be inserted, and a circular receptacle into which the wheel element with the locking unit and the force-limiting element can be inserted, the receptacle having a stop structure on its outer periphery for the end of the force-limiting element, the stop structure being formed by a spiral webbing. Thus, the first force-limiting unit can be pre-assembled and placed on the belt shaft, and if necessary, the connecting element can be pre-placed on the belt shaft. [Brief explanation of the drawings]

[0030] The invention and the technical environment will now be described by way of example with reference to the figures, which show, in a simplified manner:

[0031] The invention and the technical environment will now be described by way of example with reference to the figures, which show, in a simplified manner: [Figure 1] FIG. 10 is an exploded view of the first force limiting device and the belt shaft of the belt retractor. [Figure 2] FIG. 10 shows a housing of the first force limiting device. [Figure 3] FIG. 10 shows a locking unit of the first force limiting device. [Figure 4] FIG. 10 shows a wheel element of the first force limiting device. [Figure 5] FIG. 10 shows a driver of the first force limiting device. [Figure 6] 10A and 10B show a connecting element of the first force limiting device. [Figure 7] FIG. 2 shows a first force-limiting element of the first force-limiting device. [Figure 8] FIG. 10 is a side view of the first force limiting device without the wheel element. [Figure 9] FIG. 10 is a first detailed view showing the locking element between the driver and the coupling element. [Figure 10] FIG. 10 is a detailed view showing predetermined break structures on the wheel elements. [Figure 11] 10A and 10B show a further embodiment of a lock unit. DETAILED DESCRIPTION OF THE INVENTION

[0032] The belt retractor, at least partially shown in FIG. 1, comprises a belt shaft 1 for retracting a seat belt (not shown).

[0033] The belt retractor also includes 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 spirally shaped force limiting elements 3.1 and 3.2 (see also FIG. 7) and the driver (see also FIG. 4) formed as webbing are arranged in a receptacle of the housing 10 of the first force limiting unit 2. The free outer ends of the force limiting elements 3.1 and 3.2 abut and rest against stop structures of the receptacle (see in particular FIG. 8). At their other ends, the web-like force limiting elements 3.1 and 3.2 are arranged to rest in corresponding recesses of the driver 4.

[0034] The first force limiting device 2 also comprises a coupling element 5, which is connected to the belt shaft 1 for coupled rotation. The coupling element 5 has a starting ramp on its outer periphery (see in particular Figure 6).

[0035] The first force limiting device also comprises a wheel element 7 (see FIG. 4) and a locking unit 6 (see FIG. 3). The locking unit 6 has a substantially circular support part 6.2 to which an inwardly extending arm 6.3 is connected. The arm 6.3 has a locking element 6.1 formed at its free end. The support part 6.2 and the arm 6.3 define a plane from which the locking element 6.1 projects (projecting obliquely backward in FIG. 3).

[0036] The wheel element 7 has a first predetermined breaking structure 7.1 in its central region, by which the wheel element 7 is at least indirectly connected for interlocking rotation to the belt shaft 1 in an initial state. The wheel element 7 has a toothed structure on its outer periphery and forms a cup shape between its outer periphery and an inner receptacle having the first predetermined breaking structure 7.1. In the assembled state, the locking unit 6 is placed in this pot-shaped receptacle, with the locking element 6.1 partially protruding beyond the receptacle. The locking unit 6 is initially fixed for interlocking rotation to the wheel element 7 by a second predetermined breaking structure 7.2, as also shown in detail in FIG. 10.

[0037] In the assembled state, the locking elements 6.1, which protrude beyond the receptacle of the wheel element 7, are arranged between the connecting element 5 and the driver 4. In this case, each locking element 6.1 is assigned a starting ramp of the connecting element 5 (see Figure 8).

[0038] In the initial state of the first force-limiting device 2 shown in Fig. 8, the wheel element 7 (not shown in Fig. 8) is connected to the belt shaft 1 by a first predetermined breaking structure 7.1, so that the locking unit 6, which is connected to the wheel element 7 via a second predetermined breaking structure 7.2, also rotates together 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 initially arranged stationary in the housing 10. By triggering the triggering device 8, the relative rotation of the wheel element 7 can be stopped by engaging the blocking element 8.1 with a tooth structure on the outer periphery of the wheel element 7.

[0039] 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 broken at the first predetermined breaking structure 7.1. The belt shaft 1, and therefore the connecting element 5, also continues to rotate relative to the fixed wheel element 7 and, together with the wheel element 7, the fixed locking unit 6.

[0040] Relative rotation of the connecting element 5 with respect to the radially deflectably mounted locking element 6.1 causes relative movement of the locking element 6.1 along the starting ramp of the connecting element 5. The locking element 6.1 is thus deflected radially outward until it engages with the driver 4. A connection for coupled rotation between the connecting element 5 and the driver 4 is thus established via the locking element 6.1, and continuous rotation of the belt shaft 1 and the connecting element 5 also drives the driver 4 in a rotational movement.

[0041] The locking unit 6 with the driver 4 and the connecting element 5 then also rotates, whereby the connection of the locking unit 6 to the wheel element 7 is broken at the second predetermined breaking structure 7.2, as a result of which the locking unit 6 then begins to rotate relative to the fixed wheel element 7.

[0042] At the same time, the rotational movement of the driver 4 causes the two force limiting elements 3.1 and 3.2 to deform, thereby absorbing energy and thus providing a level of force limitation to the relative rotation of the belt shaft 1.

[0043] Due to the arrangement of the locking element 6.1 on the arm 6.3 and the design of the locking element 6.1 protruding from the wheel element 7, the locking unit 6 can be positioned offset from the plane in which force limitation occurs due to deformation of the force-limiting elements 3.1 and 3.2.

[0044] The embodiment of the locking unit 6 shown in Figure 11 has a smaller thickness 12 perpendicular to the plane formed by the support portion 6.2 and the arm 6.3 compared to the embodiment of Figure 3. In particular, the thickness of the support portion 6.2 and the arm 6.3 is 1 mm. In order for the locking element 6.1 to have sufficient strength, the starting material forming the locking unit 6 is bent over on itself. [Explanation of symbols]

[0045] 1 Belt shaft 2. First Force Limiting Device 3.1 First Force-Limiting Element 3.2 Secondary force-limiting element 4 Driver 5 Connected Components 6 Lock Unit 6.1 Locking Elements 6.2 Support part 6.3 Arm 7 Wheel Elements 7.1 First predetermined breaking structure 7.2 Second Predetermined Breaking Structure 8 Trigger Device 8.1 Block elements 9 Second Force Limiting Device 10. Housing 11 distance 12 thickness

Claims

1. 1. A belt retractor for a seat belt of a motor vehicle, comprising: - a belt shaft (1) mounted on the housing frame so as to be rotatable about an axis of rotation; at least one first force limiting device (2), said first force limiting device (2) comprising: at least one force-limiting element (3.1, 3.2), a driver (4) connected to said at least one force-limiting element (3.1, 3.2); a coupling element (5) that rotates with the belt shaft, and a locking unit (6) having at least one locking element (6.1), a first force limiting device (2) comprising: Equipped with In the 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 coupled manner, such that the driver (4) rotates together with the belt shaft (1); said at least one force-limiting element (6.1) being fixed at one end to prevent it from rotating with said belt shaft (1) and being deformed by said rotational movement of said driver (4); and wherein the at least one locking element (6.1) can be radially deflected by relative movement between the connecting element (5) and the driver (4) to bring about the force-limiting state, and the at least one locking element (6.1) in the deflected position connects the driver (4) to the connecting element (5) in an articulated rotational manner.

2. 2. The belt retractor according to claim 1, wherein the locking unit (6) has a support part (6.2), in particular an annular support part (6.2), against which the at least one locking element (6.1) is deflectable.

3. 3. The belt retractor according to claim 2, wherein the at least one locking element (6.1) is attached to the support part (6.2) by means of an arm (6.3), the support part (6.2) and the at least one arm (6.3) defining a plane from which the at least one locking element (6.1) projects.

4. Belt retractor according to any one of claims 1 to 3, wherein the locking unit (6) comprises two or more locking elements (6.1), in particular formed integrally with the support part (6.2).

5. The belt retractor according to any one of claims 1 to 4, wherein in the initial state, the belt shaft (1) is rotatable relative to the driver (4).

6. 6. The belt retractor according to claim 1, wherein the first force limiting device (2) has a trigger device (8) for triggering a transition of the first force limiting device (2) from an initial state to the force limiting state.

7. The belt retractor according to any one of claims 1 to 6, wherein the first force limiting device (2) comprises a wheel element (7) on top of which the locking unit (6) is mounted.

8. 8. The belt retractor according to claim 6 or 7, wherein in the initial state, the wheel element (7) is connected to rotate relative to the belt shaft (1) so that the locking unit (6) together with the wheel element (7) can rotate together with the belt shaft (1), and the trigger device (8) for triggering the transition fixes the wheel element (7) and thus the locking unit (6) relative to the housing frame.

9. 9. The belt retractor according to claim 8, wherein the wheel element is connected to the belt shaft (1) in such a way that the connection provided in the initial state for coupled rotation of the wheel element (7) to the belt shaft (1) is released by further relative rotation of the belt shaft (1) with respect to the fixed wheel element (7).

10. 10. The belt retractor according to claim 8 or 9, wherein the at least one locking element (6.1) is arranged such that, when the wheel element (7) is fixed, the at least one locking element (6.1) is radially biased by the connecting element (5) rotating with the belt shaft (1) and engages with the driver (4).

11. 11. The belt retractor according to claim 10, wherein the locking unit (6) is connected to the wheel element (7) in such a way that the connection for interlocking rotation of the locking unit (6) to the wheel element (7) provided in the initial state is released by a relative rotation of the locking unit (6) with respect to the wheel element (7) that occurs after engagement of the locking element (6.1) with the driver (4).

12. 12. The belt retractor according to claim 1, comprising a profile head that can be locked relative to the housing frame and a second force-limiting device (9), in particular a multi-stage second force-limiting device, which can be connected on the one hand to the profile head and on the other hand to the belt shaft (1), and which second force-limiting device (2) allows a force-limited relative rotation of the belt shaft with respect to the locked profile head.

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