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 vehicle seat belt, comprising a belt shaft mounted on a housing frame so as to be rotatable about a rotation axis, and at least one first force limiting device. The first force limiting device particularly has at least one force limiting element, a driver connected to the at least one force limiting element, a coupling element that rotates together with the belt shaft, and a locking unit having at least one locking element.

Background Art

[0002] During normal use of the belt retractor in a motor vehicle, the seat belt is wound onto or unwound from the belt shaft during fastening or unfastening, and the belt shaft performs a rotational movement about a (virtual) rotation axis. During this normal use, no force limiting device is involved in the rotational movement of the belt shaft. However, in critical situations caused by strong deceleration of the motor vehicle, elongation of the belt accompanied by deformation of the at least one force limiting element may occur, for which purpose the belt shaft is connected to the housing frame via the at least one involved force limiting element. In order 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 involved simultaneously or sequentially in the force-limited elongation of the belt webbing. A (possibly second) force limiting device may have two or more (at least two) force limiting elements, such that the two or more (at least two) force limiting elements can also be involved simultaneously or sequentially in the force-limited elongation of the belt webbing.

[0003] A trigger device is provided for coupling the force limiting element to the belt shaft to perform force-limited elongation of the belt webbing, and the trigger device can be mechanically implemented in a vehicle-sensitive manner or a belt webbing elongation-sensitive manner, or can be triggered by electronic actuation at a predetermined point in time.

Summary of the Invention

[0004] The present invention relates to a belt retractor, in which, in the force-limiting state of a first force-limiting device, possibly two or more force-limiting devices, a driver is connected to a connecting element via at least one locking element to rotate in a coupled manner, 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 motion of the driver.

[0005] The force limiting element is, in particular, a helical webbing that is deformed by the rotation of the belt shaft in the force limiting state of the associated force limiting device. Preferably, two force limiting elements designed as webbings are provided in the first force limiting device, both webbings connected to a driver at their first ends and fixed at their other ends to resist rotation relative to the housing frame. The two helical webbings are arranged in one plane, with one webbing positioned at least partially between adjacent sections of the other webbing.

[0006] The present invention relates in particular to a belt retractor provided with a second, particularly multi-stage, force limiting device in addition to a first force limiting device, wherein the second force limiting device can be connected on the one hand to a profile head that can be locked to a housing frame and on the other hand to a belt shaft, but the second force limiting device also enables 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 limiter comprises only one torsion bar, and in a preferred embodiment, the second force limiter comprises two or three torsion bars and may be provided with a switching device that can be used to control which of the torsion bars is involved in the force-limited relative rotation of the belt shaft. The belt retractor is designed such that, in particular, the belt shaft is connected to the housing frame by the second force limiter for the initial force-limited relative rotation, while the first force limiter can be switched on for force-limited relative rotation as needed or at a later time by an electronically triggerable trigger device.

[0008] The present invention relates, in particular, to the connection of a driver of a first force limiting device to a coupling element of a belt shaft. In the initial state of the first force limiting device, the belt shaft can rotate freely relative to the driver. To involve the first force limiting device in force-limited relative rotation, a coupling element connected to rotate in conjunction with the belt shaft is connected to the driver by a locking element of a locking unit. During the subsequent relative rotation of the belt shaft with respect 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 integrally connected to the belt shaft, for example. However, it is preferable that the connecting element be provided as a separate component, and that this separate component be connected to the belt shaft at least indirectly. The connecting element may be attached to the shoulder of the belt shaft, for example, and be able to rotate in conjunction.

[0010] In principle, the driver can also be formed as a single component on the force limiting element. However, preferably, the driver is designed as a separate component, particularly having a shape-fit design, and the driver is connected to the force limiting element, which is particularly designed as a webbing, via the shape-fit design.

[0011] As an example of a belt retractor having a first force limiting device and a second force limiting device, see International Publication No. 2020021003(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 that connects a driver to a belt shaft in a different manner.

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

[0014] To achieve this objective, a belt retractor for an automobile seat belt is provided, comprising a belt shaft mounted on a housing frame so as to be rotatable about a pivot axis, and at least one first force limiting device, the at least one first force limiting device comprising at least one force limiting element, a driver connected to the at least one force limiting element, a coupling element that rotates with the belt shaft, and a locking unit having at least one locking element, wherein in the force limiting state of the first force limiting device, the driver is connected to the coupling element via at least one locking element to rotate in a coupled manner, 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 motion of the driver, and at least one locking element can be radially deflected so as to result in a force limiting state by relative motion between the coupling element and the driver, and at least one locking element in the deflected position is configured to connect the driver to the coupling element to rotate in a coupled manner.

[0015] In other words, the basic idea of ​​the present invention is to displace the locking element of the locking unit axially with respect to the axis of rotation defined by the belt shaft, thereby connecting the driver to the connecting element and causing it to rotate in a coupled manner. Thus, the driver is connected to the connecting element by the radial motion of the locking element. For this purpose, the locking element may have a kind of starting inclination, which is configured to deflect the locking element radially outward when the connecting element is rotatable relative to the locking unit, thereby initiating a force-restricted state.

[0016] The locking unit includes, in particular, a support portion for attaching the locking unit to another component of the belt retractor. The support portion is particularly annular, and the locking unit may be connected to other components of the belt retractor at two or more points.

[0017] At least one locking element is connected to the support portion, so that the locking element can bend elastically relative to the support portion. Thus, the locking element is spaced apart from the support portion, and the distance is at least 1 mm, preferably at least 2 mm, and especially preferably 2.5 mm or less, particularly in the radial direction.

[0018] In this case, it is possible to provide that at least one locking element is attached to the support portion by an arm, and each arm preferably extends along the circumferential direction of the annular support portion, particularly with a gradient from the outside to the inside. In this case, the arm follows a helical path, and the length of the arm (particularly from the annular support portion to the locking element) is greater than the distance from the support portion to the locking element, particularly at least 3 or 5 times that distance, but not more than 15 times or not more than 10 times. The entire arm having the locking element at the first end is deflected to bring about a force-limiting state of the first force limiting device.

[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 protrudes at least partially from the plane formed by the support portion and the arm. In this case, the support portion and the arm perpendicular to the plane may have a thickness of 2 mm or less, preferably 1.5 mm or less, and even more preferably 1 mm or less. The locking element may be reinforced by bending the free end of the locking unit upwards so that the locking element has sufficient strength to engage between the connecting element and the driver. Thus, it is possible to offset most of the locking unit from the plane in which the connecting element with the driver is positioned to bring about the force-limiting state of the first force limiting device. This makes it possible to position the locking unit offset from the plane in which the driver rotates during force-limiting belt extension, thereby simplifying installation.

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

[0021] In a further embodiment, the locking unit is provided to have two or more locking elements, and the two or more locking elements and support portion, and, if applicable, an arm connecting the locking elements to the support portion, are provided to be formed integrally. The formation of the two or more locking elements creates a particularly non-rotating connection between the connecting element and the driver. In particular, the connecting element has a starting inclination for each locking element, so that each locking element is individually deflected radially by the starting inclination when a force-limiting condition is brought about.

[0022] In one embodiment, the first force limiter has a trigger device, particularly an electronically triggerable trigger device, and preferably a pyrotechnic drive for triggering the transition of the first force limiter from an initial state to a force limiter state. In the initial state, the belt shaft is mounted so as to be rotatable relative to a driver that is initially stationary.

[0023] In one embodiment, the first force limiting device has a (toothed) wheel element to which a locking unit is attached. The wheel element has teeth projecting outward on its outer circumference, and the trigger device is designed and positioned such that elements of the trigger device can interact with the teeth of the wheel element.

[0024] The wheel element is designed and positioned to connect to the belt shaft so that, in the initial state, the wheel element rotates in conjunction with the locking unit, and in the initial state, the locking unit can rotate together with the belt shaft. A trigger device for triggering the transition can fix the wheel element to the housing frame and thus the locking unit. A release device can stop the initial rotation of the wheel element relative to the housing frame and thus the initial rotation of the locking unit.

[0025] The wheel element is connected to the belt shaft, at least indirectly, by a first predetermined fracture structure, and the wheel element is broken at the predetermined fracture structure when the wheel element is fixed by the release device. Thus, the wheel element is connected to the belt shaft, but the connection for the wheel element's rotation to the belt shaft, which is provided in the initial state, is released by further relative rotation of the belt shaft with respect to the fixed wheel element. While the connecting element subsequently rotates relative to the fixed wheel element and thus the fixed locking element, at least one locking element is radially deflected toward the driver.

[0026] As soon as the locking element connects the connecting element to the driver in a linked rotation, the locking element is also synchronized with the further rotation of the belt shaft. At least one locking element of the locking unit is radially deflected by the connecting element, which rotates with the belt shaft, and positioned to engage with the driver once the wheel element is locked.

[0027] To enable 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, in particular on the outer periphery of an annular support portion, a form-fitting structure that interacts with a second predetermined breaking structure formed on the wheel element. Thereby, the second predetermined breaking structure is destroyed, so that the locking unit is rotatable together with the belt shaft relative to the fixed wheel element. Accordingly, the locking unit is designed and connected to the wheel element, preferably initially via the second predetermined breaking structure, such that the connection for the rotational connection of the locking unit to the wheel element, which is provided in the initial state, is released by the relative rotation of the locking unit with respect to the wheel element that occurs after the locking element engages with the driver.

[0028] In one embodiment, the wheel element is pot-shaped, so that the wheel element forms a receptacle for the locking unit, the locking unit being largely arranged in this receptacle, and only the locking elements project at least partially beyond the receptacle and thus beyond the wheel element (axially) to the outside, the locking elements being arranged with their projecting sections lying 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, simplifying the assembly process.

[0029] The first force-limiting device has, in particular, a housing into which a trigger device can be inserted. The housing also has a particularly circular receptacle into which the wheel element comprising 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 in particular by a spiral webbing. Accordingly, the first force-limiting unit is preassembled and arranged on the belt shaft, and the coupling element can optionally be arranged on the belt shaft in advance. Brief Description of the Drawings

[0030] The present invention and its technical environment will be described below with reference to the figures. The figures schematically show the following.

[0031] The present invention and its technical environment will be described below with reference to the figures. The figures schematically show the following. [Figure 1] This is an exploded view of the first force limiting device and the belt shaft of the belt retractor. [Figure 2] This figure shows the housing of the first force limiting device. [Figure 3] This diagram shows the locking unit of the first force limiting device. [Figure 4] This diagram shows the wheel element of the first force limiting device. [Figure 5] This is a diagram showing the driver for the first force limiting device. [Figure 6] This diagram shows the connecting elements of the first force limiting device. [Figure 7] This diagram shows the first force limiting element of the first force limiting device. [Figure 8] This is a side view showing the first force limiting device with the wheel element removed. [Figure 9] This is a first detailed diagram showing the locking element between the driver and the connecting element. [Figure 10] This is a detailed diagram showing a predetermined fracture structure on a wheel element. [Figure 11] This figure shows another embodiment of the locking unit. [Modes for carrying out the invention]

[0032] The belt retractor, at least partially shown in Figure 1, includes a belt shaft 1 for winding up 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 and 3.2 and a driver 4 connected to the two force limiting elements 3.1 and 3.2. When assembled, the force limiting elements 3.1 and 3.2 (see also Figure 7) and the driver (see also Figure 4), which are formed as webbing and spirally, are located within the 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 against the stop structure of the receptacle and remain stationary (see in particular Figure 8). At their other ends, the web-like force limiting elements 3.1 and 3.2 are positioned in the corresponding recesses of the driver 4.

[0034] The first force limiting device 2 also includes a connecting element 5, which is connected to the belt shaft 1 to rotate in conjunction with it. The connecting element 5 has a starting inclined portion on its outer circumference (see Figure 6 in particular).

[0035] The first force limiting device also includes a wheel element 7 (see Figure 4) and a locking unit 6 (see Figure 3). The locking unit 6 has a substantially circular support portion 6.2 to which an inwardly extending arm 6.3 is connected. A locking element 6.1 is formed at the free end of the arm 6.3. The support portion 6.2 and the arm 6.3 define a plane from which the locking element 6.1 protrudes (in Figure 3, it protrudes diagonally backward).

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

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

[0038] 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 a first predetermined fracture structure 7.1, and as a result, the lock unit 6 connected to the wheel element 7 via a second predetermined fracture structure 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 initially stationary within the housing 10. By triggering the trigger device 8, the relative rotation of the wheel element 7 can be stopped by engaging the block element 8.1 with the tooth structure on the outer circumference 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 the locking unit 6 fixed together with the wheel element 7.

[0040] The relative rotation of the connecting element 5 with respect to the radially deflectable locking element 6.1 causes the relative motion of the locking element 6.1 along the initial inclination of the connecting element 5. Thus, the locking element 6.1 is deflected radially outward until it engages with the driver 4. Thus, a connection for linked rotation between the connecting element 5 and the driver 4 is established via the locking element 6.1, and the continuous rotation of the belt shaft 1 and the connecting element 5 also drives the driver 4 in rotational motion.

[0041] Subsequently, the locking unit 6, which has the driver 4 and connecting element 5, also rotates, thereby breaking the connection of the locking unit 6 to the wheel element 7 at the second predetermined breaking structure 7.2, and as a result, the locking unit 6 subsequently rotates relative to the fixed wheel element 7.

[0042] Simultaneously, the rotational motion of the driver 4 deforms the two force limiting elements 3.1 and 3.2, thereby absorbing energy and thus providing a certain level of force limiting with respect to the relative rotation of the belt shaft 1.

[0043] 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 allow the locking unit 6 to be positioned offset from the plane where force limiting occurs due to the 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 in Figure 3. In particular, the thickness of the support portion 6.2 and the arm 6.3 is 1 mm. The starting material forming the locking unit 6 is bent on its own so that the locking element 6.1 has sufficient strength. [Explanation of symbols]

[0045] 1 Belt shaft 2. First force limiting device 3.1 First force limiting element 3.2 Second force limiting element 4 drivers 5. Connecting elements 6 Lock Units 6.1 Locking Elements 6.2 Support part 6.3 Arm 7 Wheel elements 7.1 First predetermined fracture structure 7.2 Second predetermined fracture structure 8. Trigger device 8.1 Block elements 9. Second force limiting device 10 Housing 11 distance 12 thickness

Claims

1. A belt retractor for a car seat belt, - Housing (10), - A belt shaft (1) is attached to the housing (10) so as to be rotatable around the axis of rotation, - A wheel element (7) is connected to the housing (10) so as to rotate together with the belt shaft (1), - At least one first force limiting device (2), the first force limiting device (2) is - At least one force limiting element (3.1, 3.2) with one end fixed to the housing (10), Driver (4) connected to at least one of the force limiting elements (3.1, 3.2), - A connecting element (5) that rotates together with the belt shaft, - A locking unit (6) having at least one locking element (6.1), and - A trigger device (8) that fixes the wheel element (7) to the housing (10) in order to trigger the transition of the first force limiting device (2) from its initial state to the force limiting state, A first force limiting device (2) is provided, Equipped with, In the force limiting state of the first force limiting device (2), - The driver (4) is connected to the connecting element (5) via the at least one locking element (6.1) so as to rotate together with the belt shaft (1), - The at least one force limiting element (3.1, 3.2) is fixed at one end to prevent it from rotating with the belt shaft (1) and is deformed by the rotational motion of the driver (4), - With the wheel element (7) fixed by the trigger device (8) and the rotation of the lock unit (6) stopped, the relative motion between the connecting element (5) and the stopped lock unit (6) due to the rotation of the belt shaft (1) causes at least one lock element (6.1) to be deflected radially. - The deflected at least one locking element (6.1) engages with the driver (4), thereby connecting the driver (4) to the connecting element (5) so as to rotate in a connected manner. - The rotational motion of the driver (4) deforms the at least one force limiting element (3.1, 3.2) to which one end is fixed. Belt retractor.

2. The belt retractor according to claim 1, wherein the locking unit (6) has a particularly annular support portion (6.2), and the at least one locking element (6.1) is deflectable relative to the support portion (6.2).

3. The belt retractor according to claim 2, wherein the at least one locking element (6.1) is attached to the support portion (6.2) by an arm (6.3), and the support portion (6.2) and the arm (6.3) are located in the same plane as the plane from which the at least one locking element (6.1) protrudes.

4. The belt retractor according to claim 2 or 3, wherein the locking unit (6) comprises two or more locking elements (6.1) formed integrally with the support portion (6.2).

5. In the initial state, the belt shaft (1) is rotatable relative to the driver (4), as described in any one of claims 1 to 3.

6. The belt retractor according to claim 1, wherein in the initial state, the wheel element (7) is connected to the belt shaft (1) so as to rotate in conjunction with the belt shaft (1) that the locking unit (6) can be rotated together with the wheel element (7) together with the belt shaft (1).

7. The belt retractor according to claim 1, wherein the locking unit (6) is connected to the wheel element (7) such that the connection for coupling rotation of the locking unit (6) to the wheel element (7), provided in the initial state, is released by the relative rotation of the locking unit (6) to the wheel element (7) that occurs after the locking element (6.1) engages with the driver (4).

8. The belt retractor according to any one of claims 1 to 3, comprising a profile head lockable to the housing (10) and a second force limiting device (2) in particular of a multi-stage configuration, wherein the second force limiting device is connectable on one side to the profile head and on the other side to the belt shaft (1), and the second force limiting device (2) enables force-limited relative rotation of the belt shaft with respect to the locked profile head.

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